Note: Descriptions are shown in the official language in which they were submitted.
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ENERGY ATTENUATING SAFETY SYSTEM
TECHNICAL FIELD OF THE INVENTION
This invention relates in general to energy
absorbing systems, and more particularly to an energy
absorbing system used to reduce severity of a collision
between a moving motor vehicle and a hazard by shredding
or rupturing portions of an energy absorbing element.
BACKGROUND OF THE INVENTION
Various impact attenuation devices and energy
absorbing systems have been used to prevent or reduce
damage resulting from a collision between a moving motor
vehicle and various hazards or obstacles. Prior impact
attenuation devices and energy absorbing systems such as
crash cushions or crash barriers include various types of
energy absorbing elements. Some crash barriers rely on
inertia forces to absorb energy when material such as
sand is accelerated during an impact. Other crash
barriers include crushable elements.
Some of these devices and systems have been
developed for use at narrow roadside hazards or obstacles
such as at the end of a median barrier, end of a barrier
extending along the edge of a roadway, large sign posts
adjacent to a roadway, and bridge pillars or center
piers. Such impact attenuation devices and energy
absorbing systems are installed in an effort to minimize
the extent of personal injury as well as damage to an
impacting vehicle and any structure or equipment
associated with the roadside hazard.
Examples of general purpose impact attenuation
devices are shown in U.S. Patent 5,011,326 entitled
Narrow Stationary Impact Attenuation System; U.S. Patent
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4,352,484 entitled Shear Action and Compression Energy
Absorber; U.S.. Patent 4,645,375 entitled Stationary
Impact Attenuation System; and U.S. Patent 3,944,187
entitled Roadway Impact Attenuator. Examples of
specialized energy absorbing systems are shown in U.S.
Patent 4,928,928 entitled Guardrail Extruder Terminal and
U.S. Patent 5,078,366 entitled Guardrail Extruder
Terminal. Examples of energy absorbing systems
satisfactory for use with highway guardrail systems are
shown in U.S.. Patent 4,655,434 entitled Energy Absorbing
Guardrail Terminal and U.S. Patent 5,957,435 entitled
Energy-Absorbing Guardrail End Terminal and Method.
Examples of impact attenuation devices and energy
absorbing systems appropriate for use on a slow moving or
stopped highway service vehicle are shown in U.S. Patent
5,248,129 entitled Energy Absorbing Roadside Crash
Barrier; U.S. Patent 5,199,755 entitled Vehicle Impact
Attenuating Device; U.S. Patent 4,711,481 entitled
Vehicle Impact Attenuating Device; U.S. Patent 4,008,915
entitled impact Barrier for Vehicles.
Other examples of impact attenuation devices and
energy absorbing systems are shown in U.S. Patent
5,947,452, entitled Energy Absorbing Crash Cushion; U.S.
Patent 6,293,727, entitled Energy Absorbing Systems for
Fixed Roadside Hazards TRACC; and U.S. Patent 6,536,985,
entitled Energy Absorbing System for Fixed Roadside
Hazards.
Recommended procedures for evaluating performance of
various types of highway safety devices including crash
cushions is presented in National Cooperative Highway
Research Program (NCHRP) Report 350. A crash cushion is
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generally defined as a device designed to safely stop an
impacting vehicle within a relatively short distance.
NCHRP Report 350 further classifies crash cushions as
either "redirective" or "nonredirective". A redirective
crash cushion is designed to contain and redirect a
vehicle impacting downstream from a nose or end of the
crash cushion facing oncoming traffic extending from a
roadside hazard. Nonredirective crash cushions are
designed to contain and capture a vehicle impacting
downstream from the nose of the crash cushion.
Redirective crash cushions are further classified as
either "gating" or "nongating" devices. A gating crash
cushion is one designed to allow controlled penetration
of a vehicle during impact between the nose of the crash
cushion and the beginning of length of need (LON) of the
crash cushion. A nongating crash cushion may be designed
to have redirection capabilities along its entire length.
SUMMARY OF THE INVENTION
In accordance with teachings of the present
invention, disadvantages and limitations associated with
previous energy absorbing systems and impact attenuation
devices have been substantially reduced or eliminated.
One aspect of the present invention includes an energy
absorbing system which may be installed adjacent to
roadside hazards or hazards located on a roadway to
protect occupants of a vehicle during collision with such
hazards . The system may include at least one energy
absorbing assembly which dissipates energy from a vehicle
impacting one end of the system opposite from a hazard.
When a vehicle collides with one end of the energy
absorbing system, portions of at least one energy
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absorbing element may be shredded or ruptured to
dissipate kinetic energy from the vehicle and provide
deceleration within acceptable limits to minimize injury
to occupants of the vehicle. Each energy absorbing
element may be disposed generally normal to an associated
shredder. For some applications each shredder may be
disposed generally horizontal relative to associated
energy absorbing elements. For other applications each
shredder may be disposed generally vertical relative to
associated energy absorbing elements.
Technical advantages of the present invention
include providing a relatively compact, modular energy
absorbing system satisfactory for protecting vehicles
during impact with a wide variety of hazards. Energy
absorbing systems incorporating teachings of the present
invention may be fabricated at relatively low cost using
conventional materials and processes which are well known
to the highway safety industry. The resulting systems
combine innovative structural designs with energy
absorbing techniques that are highly predictable and
reliable. Such systems may be easily repaired at
relative low cost after a vehicle impact.
Failure mechanisms associated with moving a shredder
oriented generally perpendicular through a solid plate
may include a series of small thumbnail size chunks being
knocked out or shredded or ruptured from the solid plate
in front of the shredder as the shredder proceeds
longitudinally through the solid plate. For other
applications, a shredder oriented generally perpendicular
with a solid plate may produce a single line of failure
ahead of the shredder as the shredder moves
longitudinally through the solid plate. The ruptured
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material may deflect one way or the other around the
shredder. Cooperation between shredders and energy
absorbing elements having openings and lands
incorporating teachings of the present invention results
5 in a generally consistent, reliable mode of failure which
restarts each time shredder moves from one opening
through an associated land to another opening.
In accordance with another aspect of the present
invention, a crash cushion may be provided with a
shredder and one or more energy absorbing elements to
optimize performance and repeatability of the crash
cushion by shredding or rupturing portions of at least
one energy absorbing element. Each energy absorbing
element may have alternating lands and openings which
cooperate with each other to provide safe, repeatable
deceleration of a vehicle impacting one end of the crash
cushion. The crash cushion may include a first,
relatively soft portion to absorb impact from small,
lightweight vehicles and/or slow moving vehicles. The
crash cushion may have a middle portion with one or more
energy absorbing elements and associated openings and
lands. The size of the openings and/or lands may be
varied along the length of each energy absorbing element
to provide optimum deceleration of an impacting vehicle.
The crash cushion may have a third or final portion with
one or more energy absorbing elements and associated
openings and lands designed to absorb impact from heavy,
high speed vehicles in accordance with teachings of the
present invention. The present invention may allow
reducing the number or length of energy absorbing
elements required to dissipate energy from an impacting
vehicle by varying the size of openings, spacing of lands
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or segments between the openings and/or the thickness of
each energy absorbing element. For some applications, an
energy absorbing assembly may be formed with two or more
energy absorbing elements stacked relative to each other.
Further technical advantages of the present
invention may include providing relatively low cost crash
cushions and other types of safety systems which meet the
criteria of NCHRP Report 350 including Test Level 3
Requirements. A safety system having an energy absorbing
assembly incorporating teachings of the present invention
may be satisfactorily used during harsh weather
conditions and is not sensitive to cold or moisture. The
system may be easily installed, operated, inspected and
maintained. The system may be installed on new or
existing asphalt or concrete pads. A modular safety
system incorporating teachings of the present invention
may eliminate or substantially reduce field assembly of
impact attenuation devices and energy absorbing
components. Easily replaceable parts allow quick, low
cost repair after nuisance hits and side impacts.
Elimination of easily crushed or easily bent materials
further minimizes the effect of any damage from nuisance
hits and/or side impacts with the system.
Technical benefits of the present invention may
include a modular energy absorbing system that may be
used with permanent roadside hazards or may be easily
moved from one temporary location (first work zone) to
another temporary location (second work zone). A safety
system incorporating teachings of the present invention
may also be mounted on trucks and other types of highway
service equipment.
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Technical benefits of the present invention may also
include installing one or more energy absorbing
assemblies with respective energy absorbing elements
disposed in substantially horizontal positions. As a
result, the energy absorbing elements may be more easily
replaced and/or repaired after a vehicle impact with an
associated crash cushion or other energy absorbing
system.
An energy absorbing system incorporating teachings
of the present invention may have energy absorbing
assemblies arranged in various configurations. For some
applications, only a single row of energy absorbing
assemblies may be installed adjacent to a hazard. For
other applications, three or more rows of energy
absorbing assemblies may be installed. Also, each row
may only have one energy absorbing assembly or multiple
energy absorbing assemblies. The present invention
allows modifying an energy absorbing system to minimize
possible injury to both restrained and unrestrained
occupants in a wide variety of vehicles traveling at
various speeds.
An energy absorbing system incorporating teachings
of the present invention may more easily be repaired
following impact by a vehicle. Energy absorbing elements
may be disposed in a horizontal position and securely
attached to other components of the energy absorbing
system by a relatively small number of mechanical
fasteners. For example, one bolt and associated nut may
be used to provide the holding power or structural
strength of three or four bolts and associated nuts. As
a result, the energy absorbing elements may be more
quickly and more easily replaced following a vehicle
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impact. Panels attached along sides of the energy
absorbing system may be more quickly and more easily
replaced following a vehicle impact. For some
applications modules which may be easily replaced are
used to shred energy absorbing elements to dissipate
energy from a vehicle impact. Each module may include a
bolt or other type of blunt shredder that may be easily
replaced. The present invention does not include any
type of cutter or sharp edge. An energy absorbing system
incorporating teachings of the present invention may be
installed as a modular unit, removed as a modular unit
following a vehicle impact and replaced by a new modular
unit.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the present
invention may be acquired by referring to the following
descriptions taken in conjunction with the accompanying
drawings in which like reference numbers indicate like
features and wherein:
FIGURE 1 is a schematic drawing showing an isometric
view with portions broken away of a shredder and an
energy absorbing assembly incorporating teachings of the
present invention;
FIGURE 2 is a schematic drawing in section with
portions broken away taken along lines 2-2 of FIGURE 1;
FIGURE 3 is a schematic drawing showing an exploded,
isometric view with portions broken of an energy
absorbing assembly and an energy absorbing element having
lands or segments disposed between respective openings or
holes in accordance with teachings of the present
invention;
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FIGURE 4A is a schematic drawing showing a plan view
with portions broken away of an energy absorbing system
incorporating teachings of the present invention;
FIGURE 4B is a schematic drawing showing a plan view
with portions broken away after a vehicle has collided
with one end of the energy absorbing system of FIGURE 4A;
FIGURE 4C is a schematic drawing showing a plan view
of another energy absorbing system incorporating
teachings of the present invention;
FIGURE 5 is a schematic drawing in elevation with
portions broken away showing an energy absorbing system
incorporating teachings of the present invention;
FIGURE 6 is a schematic drawing with portions broken
away showing an exploded, plan view of the energy
absorbing system, associated shredders; energy absorbing
assemblies and guide rails as shown in FIGURE 5;
FIGURE 7 is a schematic drawing showing an isometric
view of overlapping panels disposed along one side of an
energy absorbing system incorporating teachings of the
present invention;
FIGURE 8 is a schematic drawing in section with
portions broken away showing a first upstream panel and a
second downstream panel slidably disposed relative to
each other;
FIGURE 9 is a schematic drawing showing an isometric
view of a slot plate satisfactory for releasably engaging
a panel with a panel support frame in accordance with
teachings of the present invention;
FIGURE 10 is a schematic drawing showing an
isometric view with portions broken away of an energy
absorbing system and associated sled assembly
incorporating teachings of the present invention;
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FIGURE 11 is a schematic drawing showing another
isometric view with portions broken away of the energy
absorbing system and sled assembly of FIGURE 10;
FIGURE 12 is a schematic drawing in section and in
5 elevation with portions broken away showing another view
of the sled assembly and associated energy absorbing
system of FIGURE 10;
FIGURE 13 is a schematic drawing showing a plan view
with portions broken away of the sled assembly, shredders
10 and associated energy absorbing assemblies and associated
energy absorbing system of FIGURE 10;
FIGURE 14 is an enlarged, schematic drawing in
section and in elevation with portions broken away taken
along lines 14-14 of FIGURE 13;
FIGURE 15 is a schematic drawing with portions
broken away showing an exploded, isometric view of an
energy absorbing assembly such shown in FIGURE 14
incorporating teachings of the present invention;
FIGURE 16 is a schematic drawing with portions
broken away showing a plan view of energy absorbing
elements incorporating teachings of the present
invention; and
FIGURE 17 is a schematic drawing in section with
portions broken away showing a panel support frame and
attached panels satisfactory for use with an energy
absorbing system incorporating teachings of the present
invention.
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DETAILED DESCRIPTION OF THE INVENTION
The present invention and its advantages may be
better understood by referring to FIGURES 1-17 of the
drawings, like numerals being used for like and
corresponding parts of the drawings.
The terms "longitudinal," "longitudinally" and
"linear" will generally be used to describe the
orientation and/or movement of components associated with
an energy absorbing system incorporating teachings of the
present invention in a direction substantially parallel
to the direction vehicles (not expressly shown) travel on
an associated roadway. The terms "lateral" and
"laterally" will generally be used to describe the
orientation and/or movement of components associated with
an energy absorbing system incorporating teachings of the
present invention in a direction substantially normal to
the direction vehicles travel on an associated roadway.
Some components of energy absorbing systems incorporating
teachings of the present invention may be disposed at an
angle or flare (not expressly shown) relative to the
direction vehicles travel on an adjacent roadway.
The term "downstream" will generally be used to
describe movement which is approximately parallel with
and in approximately the same general direction as
movement of a vehicle traveling an associated roadway.
The term "upstream" will generally be used to describe
movement which is approximately parallel with but in
approximately an opposite direction as movement of a
vehicle traveling on an associated roadway. The terms
"upstream" and "downstream" may also be used to describe
the position of one component relative to another
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component in an energy absorbing system incorporating
teachings of the present invention.
The terms "shred, shredding, rupture and rupturing"
may generally be used to describe the results of a
shredder engaging portions of an energy absorbing element
to dissipate energy of an impacting vehicle in accordance
with teachings of the present invention. The terms
"shred, shredding, rupture and rupturing" may also be
used to describe the combined effects of ripping, tearing
and/or breaching portions of an energy absorbing element
without cutting portions of the energy absorbing element.
U.S. Patent 4,655,434 entitled Energy Absorbing Guardrail
Terminal and U.S. Patent 5,957,435 entitled Energy
Absorbing Guardrail End Terminal and Method show examples
of shredding material disposed between spaced openings to
absorb kinetic energy of an impacting vehicle.
The terms "gore" and "gore area" may be used to
describe the area where two roadways diverge or converge.
A gore is typically bounded on two sides by the edges of
the roadways which join at the point of divergence or
convergence. Traffic flow is often in the same direction
on both of the roadways. A gore area may include
shoulders or marked pavement between the roadways. The
third side or third boundary of a gore area may sometimes
be defined as approximately sixty (60) meters from the
point of divergence or convergence of the roadways.
The term "roadside hazard" may be used to describe
permanent, fixed roadside hazards such as a large sign
post, a bridge pillar or a center pier of a bridge or
overpass. Roadside hazards may also include a temporary
work area disposed adjacent to a roadway or located
between two roadways. A temporary work area may include
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various types of equipment and/or vehicles associated
with road repair or construction. The term "roadside
hazard" may also include a gore area or any other
structure located adjacent to a roadway and presenting a
hazard to oncoming traffic.
The terms "hazard" and "hazards" may be used to
describe both roadside hazards and hazards located on a
roadway such as slow moving vehicles or equipment and
stopped vehicles or equipment. Examples of such hazards
may include, but are not limited to, highway safety
trucks and equipment performing construction, maintenance
and repair of an associated roadway.
Various components of an energy absorbing system
incorporating teachings of the present invention may be
formed from commercially available structural steel
materials. Examples of such materials include steel
strips, steel plates, structural steel tubing, structural
steel shapes and galvanized steel. Examples of
structural steel shapes include W shapes, HP shapes,
beams, channels, tees, and angles. Structural steel
angles may have legs with equal or unequal width. The
American Institute of Steel Construction publishes
detailed information concerning various types of
commercially available structural steel materials
satisfactory for use in fabricating energy absorbing
systems incorporating teachings of the present invention.
For some applications, various components of an
energy absorbing system incorporating teachings of the
present invention may be formed from composite materials,
cermets and any other material satisfactory for use with
highway safety systems. The present invention is not
limited to only forming energy absorbing systems from
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steel based materials. Any metal alloy, nonmetallic
materials and combinations thereof which are satisfactory
for use in highway safety systems may be used to form an
energy absorbing system incorporating teachings of the
present invention. For some applications, energy
absorbing elements incorporating teachings of the present
invention may be formed from mild steel.
Energy absorbing systems 20, 20a, 20b and 20c
incorporating teachings of the present invention may
sometimes be referred to as crash cushions, crash
barriers, or roadside protective systems. Energy
absorbing systems 20, 20a, 20b and 20c may be used to
minimize the results of a collision between a motor
vehicle (not expressly shown) and various types of
hazards. Energy absorbing systems 20, 20a, 20b and 20c
and other energy absorbing systems incorporating
teachings of the present invention may be used for both
permanent installation and temporary work-zone
applications. Energy absorbing systems 20, 20a, 20b and
20c may sometimes be described as nongating, redirective
crash cushions. Energy absorbing systems 20, 20a, 20b
and 20c and other energy absorbing systems incorporating
teachings of the present invention may meet or exceed
NCHRP Report 350, Test Level 3 requirements.
Various features of the present invention will be
described with respect to energy absorbing system 20 as
shown in FIGURES 4A and 4B, energy absorbing system 20a
as shown in FIGURE 4C and energy absorbing system 20b as
shown in FIGURES 5 and 6 and energy absorbing system 20c
as shown in FIGURES 10-15. Various types of shredders
and energy absorbing assemblies incorporating teachings
of the present invention may be used with energy
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absorbing systems 20, 20a, 20b and 20c. The present
invention is not limited to shredders 116 and 216, energy
absorbing assemblies 86 and 286 or associated energy
absorbing elements 100, 100a, 100b, 100c and 100d.
5 For some applications energy absorbing systems 20,
20a, 20b and 20c may be installed as respective modular
units. Also various components and/or subsystems of each
energy absorbing system may be installed and removed as
separate, individual modules. For example, energy
10 absorbing assemblies may be formed into rows and engaged
with respective cross ties and guide rails formed in
accordance with teachings of the present invention. The
resulting base module may then be installed adjacent to a
hazard. Panel support frames and panels may also be
15 manufactured and assembled as a module or series of
modules which are delivered to a work site for
installation on the associated base module. Sled
assemblies 40, 40a, 40b and 40c may also be assembled and
delivered to a work site as a single module. Threaders
formed in accordance with teachings of the present
invention may also be installed as replaceable modules.
Energy absorbing systems 20 and 20a may include sled
assembly 40. Energy absorbing system 20b may include
sled assembly 40b. Energy absorbing system 20c may
include sled assembly 40c. First end 41 of each sled
assembly 40, 40b and 40c may correspond generally with
first end 21 of associated energy absorbing systems 20,
20a and 20b and 20c. Materials used to form sled
assemblies 40, 40b and 40c are preferably selected to
allow sled assemblies 40, 40b and 40c to remain intact
after impact by a high speed vehicle.
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The dimensions and configuration of first end 41 of
sled assemblies 40, 40b and 40c, defined in part by
corner posts 42 and 43, top brace 141 and bottom brace
51, may be selected to catch or gather an impacting
vehicle. During a collision between a motor vehicle and
first end 21 of energy absorbing systems 20, 20a, 20b or
20c, kinetic energy from the colliding vehicle may be
transferred from first end 41 to other components of
associated sled assembly 40, 40b or 40c. The dimensions
and configuration of end 41 may also be selected to
effectively transfer kinetic energy even if a vehicle
does not impact the center of first end 41 or if a
vehicle impacts end 41 at an angle other than parallel
with the longitudinal axis of associated energy absorbing
system 20, 20a, 20b and 20c.
Respective panels 160 may be attached to the sides
of each sled assembly 40, 40b and 40c extending from
respective first end 41. For purposes of describing
various features of the present invention, panels 160 are
shown broken away from the sides of sled assembly 40b in
FIGURE 5. Panels 160 have been removed from one side of
sled assembly 40c in FIGURES 10 and 11.
Roadside hazard 310 shown in FIGURES 4A, 4C, and 5
may be a concrete barrier extending along the edge or
side of a roadway (not expressly shown). Roadside hazard
310 may also be a concrete barrier extending along the
median between two roadways. Roadside hazard 310 may be
a permanent installation or a temporary installation
associated with a work area. Roadside hazard 310 may
sometimes be described as a "fixed" barrier or "fixed"
obstacle even though concrete barriers and other
obstacles adjacent to a roadway or disposed in a roadway
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may from time to time be moved or removed. An energy
absorbing system incorporating teachings of the present
invention is not limited to use with only concrete
barriers. Energy absorbing systems incorporating
teachings of the present invention may be installed
adjacent to various types of hazards facing oncoming
traffic.
Examples of shredders and energy absorbing
assemblies incorporating teachings of the present
invention are shown in FIGURES 1-3. Energy absorbing
assembly 86, as shown in FIGURES 1, 2 and 3, may
sometimes be referred to as a "box beam." Energy
absorbing assembly 86 may include a pair of supporting
beams 90 disposed longitudinally parallel with each other
and spaced from each other. Each supporting beam 90 may
have a generally C-shaped or U-shaped cross section.
Supporting beams 90 may sometimes be described as
channels.
The C-shaped cross section of each supporting beam
90 may be disposed facing each other to define a
generally rectangular cross section for each energy
absorbing assembly 86. The C-shaped cross section of
each supporting beam 90 may be defined in part by web 92
and flanges 94 and 96 extending therefrom. A plurality
of holes 98 may be formed in flanges 94 and 96 to attach
one or more energy absorbing elements 100 with energy
absorbing assembly 86. For one application, supporting
beams or channels 90 may have an overall length of
approximately eleven feet with a web width of
approximately five inches and a flange height of
approximately two inches. A wide variety of fasteners
may be inserted through holes 98 in supporting beams 90
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and corresponding holes 108 formed in energy absorbing
element 100 to satisfactorily attach energy absorbing
elements 100 with supporting beams 90.
For embodiments shown in FIGURES 1, 2 and 3,
fasteners 103 preferably extend through respective holes
108 in energy absorbing element 100 and respective holes
98 in flanges 94 and 96. Fasteners 103 may be selected
to allow easy replacement of energy absorbing element 100
after collision of a motor vehicle with one end of an
associated energy absorbing system.
One requirement for attaching energy absorbing
elements 100 with supporting beams 90 includes providing
appropriately sized shredding zone 118 as shown in FIGURE
3 between supporting beams 90 to accommodate the
associated shredder 116. For some applications, a
combination of long bolts and short bolts may be
satisfactorily used. For other applications, the
mechanical fasteners may be blind threaded rivets and
associated nuts. A wide variety of blind rivets, bolts
and other fasteners may be satisfactorily used with the
present invention. Examples of such fasteners are
available from Huck International, Inc., located at 6
Thomas, Irvine, California 92718-2585. Power tools
satisfactory for installing such blind rivets are also
available from Huck International and other vendors.
For embodiments shown in FIGURES 1, 2, and 3, only
one energy absorbing element 100 may be attached to
flanges 94 on one side of energy absorbing assembly 86.
For some applications, another energy absorbing element
100 may be attached to flanges 96 on the opposite side of
energy absorbing assembly 86. For other applications,
multiple energy absorbing elements 100 and spacers (not
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expressly shown) may be attached to one or both flanges
94 and 96.
A row of holes or openings 110 may be formed
extending generally along a longitudinal center line of
energy absorbing element 100. Openings or holes 110 may
also be described as perforations. For some
applications, openings 110 may have a generally circular
configuration with a diameter of approximately one inch.
Openings 110 are preferably spaced from each other with
respective lands or segments 112 disposed there between
as shown in FIGURES 1, 2 and 3. The spacing between
adjacent holes 110, the dimensions of holes 110 and
corresponding lands or segments 112 may be varied in
accordance with teachings of the present invention to
control the amount of force or energy required to move
respective shredder 116 therethrough.
Without the presence of openings 110, the force
required to move shredder 116 through energy absorbing
element 100 may vary depending upon the specific type of
failure mechanism. The failure mechanism associated with
moving shredder 116 longitudinally through a solid plate
may vary along the length of the solid plate. The
presence of openings 110 and segments 112 results in
improved repeatability and accuracy of energy absorption
as shredder 116 moves longitudinally through energy
absorbing element 100.
The configuration and dimensions of openings 110 and
segments 112 may be substantially varied in accordance
with teachings of the present invention to provide
desired energy absorbing characteristics for an
associated energy absorbing assembly. For example,
openings 110 may have a generally circular, oval, slot,
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rectangular, star or any other suitable geometric
configuration.
For some applications, openings 110 and segments 112
may have substantially uniform dimensions along the
5 length of each energy absorbing element 100. For other
applications, the dimensions of openings 110 and/or the
dimensions of respective segments 112 may be varied to
provide for a relatively "soft" deceleration when a
vehicle initially impacts an associated energy absorbing
10 assembly followed by increasing deceleration or
increasing energy absorption along a middle portion of an
associated energy absorbing element 100. The last
portion of the associated energy absorbing element 100
may provide reduced deceleration or reduced energy
15 absorption as the speed of an impacting vehicle
decreases.
Alternatively, openings 110 in energy absorbing
elements 100 need not be discrete, but may be
interconnected by slots (not expressly shown). As
20 shredder 116 moves through openings 116 and associated
slots, energy absorbing element 100, already divided by
the slots interconnecting openings 110, resists the
movement of shredder 116. Shredder 116 may bend or
otherwise deform the slots in energy absorbing element
100, wherein energy is absorbed and dissipated.
The number of energy absorbing elements 100 and
their length and thickness may be varied depending upon
the intended application for the resulting energy
absorbing assembly. Increasing the number of energy
absorbing elements, increasing their thickness and/or
increasing length will allow the resulting energy
absorbing assembly to dissipate an increased amount of
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kinetic energy. Benefits of the present invention
include the ability to vary the geometric configuration
and number of openings 110 and segments 112 and select
appropriate materials to form energy absorbing elements
100 depending upon the intended application for the
resulting energy absorbing assembly. Energy absorbing
elements 100 and other components of an energy absorbing
system incorporating teachings of the present invention
may be galvanized to insure that they retain their
desired tensile strength and are not affected by
environmental conditions which may cause rust or
corrosion during the life of the associated energy
absorbing system.
For some embodiments such as shown in FIGURE 1-3, 5
and 6, each shredder 116 may be disposed adjacent to one
end of energy absorbing assembly 86. As discussed later
in more detail, a pair of shredders 116 may be attached
to sled assembly 40b in accordance with teachings of the
present invention. For some applications shredders 116
may be disposed generally horizontal relative to sled
assembly 40b and an associated roadway (not expressly
shown). Each energy absorbing element 100 and associated
slot 102 may be disposed generally vertical relative to
respective shredder 116 and the associated roadway.
The dimensions associated with each shredder 116 are
preferably compatible with slot 102 formed in the end of
each energy absorbing element 100 adjacent to respective
shredder 116 and shredding zone 118 formed between
associated supporting beams 90. The dimensions are
selected to allow shredder 116 to slide longitudinally
between flanges 94 and 96 of adjacent supporting beams
90. For one application, slot 102 at first end 101 may
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be formed along the centerline of energy absorbing
element 100 with a width of approximately three quarters
of an inch and a length of approximately six inches.
The diameter of shredder 116 may be smaller than the
diameter of openings 110. This need not always be the
case however. The diameter of shredder 116 may be the
same or even larger than the diameter of openings 110.
For some applications shredder 116 may be a bolt having a
diameter of approximately one-half of one inch and a
length of approximately twelve inches. Specific
dimensions of shredder 116 and associated energy
absorbing elements 100 may be varied depending upon the
amount of kinetic energy which will be dissipated by
energy absorbing assembly 86.
Material used to form each shredder 116 will depend
upon the material used to form associated energy
absorbing elements 100. For some applications, shredder
116 may have a minimum Rockwell hardness of C39.
Shredders having various configurations such as
cylindrical bars with generally circular cross-sections
or bars with generally square or rectangular
cross-sections (not expressly shown) may also be
satisfactorily used with an energy absorbing assembly
incorporating teachings of the present invention.
For some applications, energy absorbing assembly 86
may remain relatively stationary or fixed while an
associated shredder 116 moves longitudinally through
openings 110 and segments 112 to absorb energy from an
impacting vehicle. For other applications (not expressly
shown), shredder 116 may remain relatively fixed while an
associated energy absorbing assembly 86 including
openings 110 and segments 112 moves longitudinally with
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respect to shredder 116 to absorb energy from an
impacting vehicle.
Energy absorbing element 100 may provide
deceleration characteristics tailored for specific
vehicle weights and speeds. For example, during
approximately the first few feet of travel of shredder
116 through associated energy absorbing assembly 86, two
stages of stopping force or deceleration appropriate for
a vehicle weighing approximately 820 kilograms may be
provided. The remaining travel of shredder 116 through
associated energy absorbing assembly 86 may provide
stopping force appropriate for larger vehicles weighing
approximately 2,000 kilograms. Variations in the
location, size, configuration and number of energy
absorbing elements 100 allows energy absorbing assembly
86 to provide safe deceleration of vehicles weighing
between 820 kilograms and 2,000 kilograms.
FIGURE 4A shows energy absorbing system 20 in its
first position, extending longitudinally from roadside
hazard 310. Sled assembly 40, slidably disposed at first
end 21 of energy absorbing system 20, may sometimes be
referred to as an "impact sled." Slots 102 may be used
to receive respective shredders 116 during installation
and alignment of sled assembly 40 with energy absorbing
elements 100. First end 21 of energy absorbing system 20
including first end 41 of sled assembly 40 preferably
face oncoming traffic. Second end 22 of energy absorbing
system 20 may be securely attached to the end of roadside
hazard 310 facing oncoming traffic. Energy absorbing
system 20 is typically installed in its first position
with first end 21 longitudinally spaced from second end
22 as shown in FIGURE 4A.
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A plurality of panel support frames 60a-60e may be
spaced longitudinally from each other and slidably
disposed between first end 21 and second end 22. Panel
support frames 60a-60e may sometimes be referred to as
"frame assemblies." The number of panel support frames
may be varied depending upon the desired length of an
associated energy absorbing system. Multiple panels 160
may be attached to sled assembly 40 and panel support
frames 60a-60e. Panels 160 may sometimes be referred to
as "fenders" or "fender panels." One example of a panel
support frame satisfactory for use with energy absorbing
systems 20 20a, 20b and 20c is shown in FIGURE 16.
When a vehicle impacts with first end 21 of energy
absorbing system 20, sled assembly 40 will move generally
longitudinally toward roadside hazard 310. Energy
absorbing assemblies 86 (not expressly shown in FIGURES
4A and 4B) will absorb energy from the impacting vehicle
during this movement. Movement of panel support frames
60a-60e and associated panels 160 relative to each other
may also absorb energy from a vehicle impacting first end
21.
FIGURE 4B is a schematic drawing showing a plan view
of sled assembly 40 and panel support frames 60a-60e and
their associated panels 160 collapsed adjacent to each
other. Further longitudinal movement of sled assembly 40
toward roadside hazard 310 is prevented by panel support
frames 60a-60e. The position of energy absorbing system
20 as shown in FIGURE 4B may be referred to as the
"second" position. During most vehicle collisions with
end 21 of energy absorbing system 20, sled assembly 40
will generally move only a portion of the distance
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between the first position as shown in FIGURE 4A and the
second position as shown in FIGURE 4B.
Panel support frames 60a-60e, associated panels 160
and other components of energy absorbing system 20
5 cooperate with each other to redirect vehicles striking
either side of energy absorbing system 20 back onto an
associated roadway. Respective panels 160 may be
attached to sled assembly 40 and preferably extend over a
portion of respective panels 160 attached to panel
10 support frame 60a. Ina corresponding manner, panels 160
attached to panel support frame 60a preferably extend
over a corresponding portion of panels 160 attached to
panel support frame 60b. Various components of energy
absorbing system 20 provide substantial lateral support
15 to panel support frames 60a-60e and panels 160.
First end 161 of each panel 160 may be securely
attached to sled assembly 40 or respective panel support
frames 60a-60d as appropriate. Each panel 160 may also
be slidably attached to one or more downstream panel
20 support frames 60a-60e. Up stream panels 160 overlap
down stream panels 160 to allow telescoping or nesting of
respective panels 160 as panel support frames 60a-60e
slide toward each other. Subsets of panel support frames
60a-60e and panels 160 may be grouped together to form a
25 one-bay group or a two-bay group.
For purposes of illustration, second end 162 of each
upstream panel 160 is shown in FIGURES 4A and 4B
projecting a substantial distance laterally at the
overlap with the associated downstream panel 160. Panels
160 may nest closely with each other to minimize any
lateral projection at second end 162 which might snag a
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vehicle during a reverse angle impact with either side of
energy absorbing system 20.
FIGURE 4C is a schematic drawing showing a plan view
of energy absorbing system 20a in its first position,
extending longitudinally from roadside hazard 310.
Energy absorbing system 20a may include first end 21
facing oncoming traffic and second end 22 securely
attached to roadside hazard 310. Energy absorbing system
20a also includes sled assembly 40, panel support frames
60a-60g and respective panels 160.
Panels 160 extending along both sides of energy
absorbing systems 20 and 20a may have substantially the
same configuration. However, the length of panels 160
may vary depending on whether the respective panel is a
"one-bay panel" or a "two-bay panel." For purposes of
explanation, a "bay" is defined as the distance between
two adjacent panels support frames 60.
The length of panels 160 designated as "two-bay
panels" is selected to span the distance between three-
panel support frames when energy absorbing systems 20 and
20a are in their first position. For example, first end
161 of a two-bay panel 160 is preferably securely
attached to upstream panel support frame 60a. Second end
162 of the two-bay panel 160 is preferably slidably
attached to downstream panel support frame 60c. Another
panel support frame 60b is slidably coupled with two-bay
panels 160 intermediate first end 161 and second end 162.
When sled assembly 40 hits panel support frame 60a
which may in turn contact panel support frame 60b and
then 60c, etc., the panel support frames 60a-60g and
attached panels 160 are accelerated toward roadside
hazard 310. The inertia of panel support frames 60a-60g
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and attached panels 160 contributes to deceleration of an
impacting vehicle.
If the panel support frame of a one-bay group is
hit, the one-bay group will be coupled to its own
associated panels 160 and, therefore, will have
relatively high inertia. To soften deceleration of an
impacting vehicle, a two-bay group is preferably disposed
downstream from each one-bay group. When sled assembly
40, or one or more panel support frames being pushed by
sled assembly 40, contacts the first panel support frame
of a two-bay group (e.g., panel support frame 60d), the
inertia may be the same or slightly more than (because of
the longer panels 160) the inertia of a one-bay group.
However, when the second panel support frame of the two-
bay group (e.g., panel support frame 60e) is contacted,
the second panel support frame 60 may have a lower
inertia because it is only slidably coupled to the
associated panels 160. Therefore, deceleration is
somewhat reduced.
Energy absorbing system 20a has the following groups
of bays: 2-2-1-2-2, where 112" means two bays and 111"
means one bay. Beginning at sled assembly 40 and moving
toward roadside hazard 310, energy absorbing system 20a
has a two-bay group (counting sled assembly 40 as a bay
in and of itself), another two-bay group, a one-bay
group, followed by a two-bay group and another two-bay
group.
Energy absorbing system 20b as shown in FIGURES 5
and 6 may include sled assembly 40b and multiple energy
absorbing assemblies 86 aligned in respective rows 188
and 189 extending generally longitudinally from hazard
310 and generally parallel with each other. Sled
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assembly 40b may have a modified configuration as
compared with sled assembly 40. For some applications
guide rails 208 and 209 may also be attached with energy
absorbing assemblies 86. See FIGURES 2 and 3.
Energy absorbing assemblies 86 may be secured to
each other by a plurality of cross braces 24.
Cooperation between cross braces 24 and energy absorbing
assemblies 86 results in energy absorbing system 20b
having a relatively rigid frame structure. As a result,
energy absorbing system 20b may be better able to safely
absorb impact from a motor vehicle that strikes sled
assembly 40b either offset from the center of end 21 or
that strikes end 21 at an angle other than approximately
parallel with energy absorbing assemblies 86.
As shown in FIGURE 5, nose cover 83 may be attached
to sled assembly 40b proximate first end 21 of energy
absorbing system 20b. Nose cover 83 may be a generally
rectangular sheet of flexible plastic type material.
Opposite edges of nose cover 83 may be attached to
corresponding opposite sides of sled assembly 40b at end
41. Nose cover 83 may include a plurality of chevron
delineators 84 which are visible to oncoming traffic
approaching roadside hazard 310. Various types of nose
covers, reflectors and/or warning signs may also be
mounted on sled assemblies 40, 40b and 40c and along each
side of energy absorbing systems 20, 20a, 20b and 20c.
For some applications, each row 188 and 189 may
contain two or more energy absorbing assemblies 86.
Energy absorbing assemblies 86 in row 188 may be spaced
laterally from energy absorbing assemblies 86 in row 189.
Energy absorbing assemblies 86 may be securely attached
to concrete foundation 308 in front of roadside hazard
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310. Each row 188 and 189 of energy absorbing assemblies
86 may have respective first end 187 which corresponds
generally with first end 21 of energy absorbing system
20b. First end 41 of sled assembly 40b may also be
disposed adjacent to first end 187 of rows 188 and 189
prior to a vehicle impact.
A pair of ramps 32 may be provided at end 21 of
energy absorbing system 20b to prevent small vehicles or
vehicles with low ground clearance from directly
impacting first ends 187 of rows 188 and 189. Similar
ramps 32 are shown in FIGURE 10 at first end 21 of energy
absorbing system 20c. If ramps 32 are not provided, a
small vehicle or vehicle with low ground clearance may
contact either or both first ends 187 and experience
severe deceleration with substantial damage to the
vehicle and/or injury to occupants in the vehicle.
Various types of ramps and other structures may be
provided to ensure that a vehicle impacting end 21 of
energy absorbing system 20b will properly engage sled
assembly 40b and not directly contact first ends 187 of
rows 188 and 189.
Each ramp 32 may include leg 34 with tapered surface
36 extending therefrom. Connectors (not expressly shown)
may be used to securely engage each ramp 32 with
respective energy absorbing assembly 86. For some
applications, leg 34 may have a height of approximately
six and one-half inches. Other components associated
with energy absorbing system 20b such as energy absorbing
assemblies 86 and guide rails 208 and 209 may have a
generally corresponding height. Limiting the height of
ramps 32 and energy absorbing assemblies 86 will allow
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such components to pass under a vehicle impacting with
end 41 of sled assembly 40.
Tapered surfaces 36 may have a length of
approximately thirteen and one-half inches. Tapered
5 surfaces 36 may be formed by cutting a structural steel
angle (not expressly shown) having nominal dimensions of
three inches by three inches by one-half inch thick into
sections with appropriate lengths and angles. The
sections of structural steel angle may be attached to
10 respective legs 34 using welding techniques and/or
mechanical fasteners. Ramps 32 may also be referred to
as "end shoes."
An energy absorbing system formed in accordance with
teachings of the present invention may be mounted on or
15 attached to either a concrete or asphalt foundation (not
expressly shown). For embodiments such as shown in
FIGURES 5 and 8, concrete foundation 308 may extend both
longitudinally and laterally from roadside hazard 310.
As shown in FIGURES 5 and 6, energy absorbing assemblies
20 86 are preferably disposed on and securely attached to a
plurality of crossties 24. Each crosstie 24 may be
secured to concrete foundation 308 using respective
anchor bolts 26. Various types of mechanical fasteners
and anchors in addition to anchor bolts 26 may be
25 satisfactorily used to secure crossties 24 with concrete
foundation 308. The number of crossties and the number
of anchors used with each crosstie may be varied as
desired for each energy absorbing system.
Crossties 24 may be formed from structural steel
30 strips having a nominal width of three inches and a
nominal thickness of one half inch. The length of each
crosstie 24 may be approximately twenty-two inches.
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Three holes may be formed in each crosstie 24 to
accommodate anchor bolts 26. During a vehicle collision
with either side of energy absorbing system 20, crossties
24 are placed in tension. The materials used to form
crossties 24 and their associated configuration are
selected to allow crossties 24 to deform in response to
tension from such side impacts and to absorb energy from
the impacting vehicle.
For some installations, anchor bolts 26 may vary in
length from approximately seven inches (7") to
approximately eighteen inches (18"). For some
applications, holes (not expressly shown) may be formed
in an asphalt or concrete foundation to receive
respective anchor bolts 26. Various types of adhesive
materials may also be placed within the holes to secure
anchor bolts 26 in place. Preferably anchor bolts 26 do
not extend substantially above the tops of associated
nuts 27. Concrete and asphalt anchors and other
fasteners satisfactory for use in installing an energy
absorbing system incorporating teachings of the present
invention are available from Hilti, Inc., at P.O. Box
21148, Tulsa, Oklahoma 74121.
For purposes of describing embodiments shown in
FIGURES 5 and 6, supporting beams 90 immediately adjacent
to crossties 24 are designated 90a. The respective
supporting beams 90 disposed immediately thereabove are
designated 90b. Supporting beams 90a and 90b may have
substantially identical dimensions and configurations
including respective web 92 with flanges or flanges 94
and 96 extending therefrom. Four crossties 24 may be
attached to web 92 of supporting beams 90a opposite from
respective flanges 94 and 96. As a result, the generally
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C-shaped cross section of each supporting beam 90a
extends away from respective crossties 24.
The number of crossties 24 attached to each
supporting beam 90a may be varied depending upon the
intended use of the resulting energy absorbing system.
For energy absorbing system 20b, two supporting beams 90a
are spaced laterally from each other and attached to four
crossties 24. Conventional welding techniques and/or
mechanical fasteners (not expressly shown) may be used to
attach supporting beams 90a with crossties 24.
A pair of guide rails or guide beams 208 and 209 may
be attached to respective supporting beams 90b. Guide
rails 208 and 209 are shown in FIGURE 6 and are not shown
in FIGURE 5. For some applications, guide rails 208 and
209 may be formed from structural steel angles having
legs of equal width such as three inches by three inches
and a thickness of approximately one-half of an inch.
For other applications, a wide variety of guide rails may
be used. The present invention is not limited to guide
rails or guide beams 208 and 209. For embodiments
represented by energy absorbing system 20c, guide rails
208 and 209 may have similar configurations and
dimensions as associated supporting beams 290.
Guide rails 208 and 209 may each have first leg 211
and second leg 212 which intersect each other at
approximately a ninety-degree angle. A plurality of
holes (not expressly shown) may be formed along the
length of first leg 211 to allow attaching guide rails
208 and 209 with respective supporting beams 90b.
Mechanical fasteners 103a which may be longer than
mechanical fasteners 103 may be used to attach guide
rails 208 and 209 with supporting beams 90b.
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The length of guide rails 208 and 209 may be longer
than the length of the associated rows 188 and 189 of
energy absorbing assemblies 86. When energy absorbing
system 20b is in its second position panel support frames
60a-60e are disposed immediately adjacently to each other
which prevents further movement of sled assembly 40b.
Therefore, it is not necessary for rows 188 and 189 of
energy absorbing assemblies 86 to have the same length as
guide rails 208 and 209.
As shown in FIGURES 5 and 6, corner posts 42 and 43
may be formed from structural steel strips having a width
of approximately four inches and a thickness of
approximately three quarters of an inch. Each corner
post 42 and 43 may have a length of approximately thirty-
two inches.
Top brace 141 preferably extends laterally between
corner posts 42 and 43. Bottom brace 51 preferably
extends laterally between corner post 42 and corner post
43 immediately above guide rails 208 and 209. A pair of
braces 148 and 149 may extend diagonally from top brace
141 to a position immediately above guide rails 208 and
209. Only brace 148 is shown in FIGURE 5.
A pair of guide assemblies 54 may be respectively
attached with the end of each diagonal brace 148 and 149.
Only one guide assembly 54 is shown in FIGURE 5. The
dimensions of each guide assembly 54 may be selected to
allow contact associated guide beams or guide rails 208
and 209. For'some applications, each guide assembly 54
may be formed with a relative short angle approximately
the same dimensions and configurations. Guide assemblies
54 cooperate with each other to insure that sled assembly
40b may slide longitudinally along guide rails 208 and
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209 in the direction of an associated hazard such as
roadside hazard 310. Inertia of sled assembly 40b and
friction associated with sliding over the top of guide
rails 208 and 209 will contribute to deceleration of an
impacting vehicle.
Most impacts between a motor vehicle and end 41 of
sled assembly 40b will generally occur at a location
substantially above energy absorbing assemblies 86. As a
result, vehicle impact with end 41 will generally result
in applying a rotational moment to sled assembly 40b
which forces guide assemblies 54 to bear down on the top
of leg 211 of respective guide rails 208 and 209.
During a collision between a motor vehicle and end
41 of sled assembly 40b, force from the vehicle may be
transferred from corner posts 42 and 43 to top brace 141
through diagonal braces 148 and 149 to respective guide
assemblies 54. As a result, guide assemblies 54 will
apply force to guide rails 208 and 209 to maintain
desired orientation of sled assembly 40b relative to
energy absorbing assemblies 86.
As shown in FIGURES 1 and 6 connectors 214 may be
attached to bottom brace 51. Connectors 214 may be
spaced laterally from each other to receive respective
shredders 116. Connectors 224 and 226 are also
preferably attached to and extend from respective corner
posts 43 and 42. Respective shredders 116 may be
attached to connectors 214, 224 and 226.
Support plates 234 and 236 are preferably disposed
immediately adjacent to respective shredders 116 opposite
from associated energy absorbing assemblies 86. For the
embodiment shown in FIGURES 1 and 6 support plate 234 may
be attached to respective support post 43 and respective
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connector 214. Support plate 236 may be attached to
respective support post 42 and respective connector 214.
Spacer 244 may be installed between bottom brace 51 and
horizontal support plate 234 proximate corner post 43. A
5 similar spacer (not expressly shown) may be installed
between bottom brace 51 and horizontal support plate 236
proximate corner post 42. Backup plate 238 may be
secured to bottom brace 51 opposite from associated
shredders 116. Backup plate 238 provides additional
10 support for connectors 214 and horizontal support plates
234, 236.
Sled assembly 40b may be slidably disposed on guide
rails 208 and 209 and aligned with first end 187 of
energy absorbing assemblies 86 with shredders 116
15 disposed in respective slots 102. The dimensions of
shredder 116 and shredding zone 118 between associated
supporting beams 90 are selected to allow each shredder
116 to fit between associated flanges 94 and 96 of
associated supporting beams 90.
20 During a collision with end 21 of energy absorbing
system 20b, a vehicle will often experience a
deceleration spike as momentum is transferred from the
vehicle to sled assembly 40b which results in sled
assembly 40b and the vehicle moving in unison with each
25 other. The amount of deceleration due to the momentum
transfer is a function of the weight of sled assembly
40b, along with the weight and initial speed of the
vehicle. As sled assembly 40b slides longitudinally
toward roadside hazard 310, guide assemblies 54 will
30 contact respective guide rails 208 and 208 to maintain
desired alignment between sled assembly 40b, energy
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absorbing assemblies 86, shredders 116 and respective
shredding zones 118.
When a vehicle impacts the first end 41 of the sled
assembly 40b, sled assembly 40b will move toward hazard
310. Shredders 116, seated in respective slots 102 will
engage adjacent energy absorbing elements 100. Shredders
116 will move through adjacent first land or segment 112
shredding the material in land 112. Each shredder 116
will pass through first land 112 and enters the first
opening 110. Shredder 116 will then enter the next land
112, shredding the material. The process repeats as
shredders 116 pass through lands 112 and openings 110
between respective lands 112. Openings 110 provide
reliability in the failure of associated energy absorbing
element 100 by both ensuring that shredder 116 remains on
a desired path through energy absorbing element 100 and
also ruptures energy absorbing element 100 with a
predictable amount of force.
The center portion of each energy absorbing element
100 will be shredded between respective supporting beams
90, while the top and bottom portions of each energy
absorbing element 100 remains fixed to respective
supporting beams 90 by bolts 103. The center portion of
each energy absorbing element 100 continues to be
shredded as sled assembly 40b continues to push
respective shredders 116 therethrough. The shredding of
portions of energy absorbing elements 100 will stop when
kinetic energy from the impacting vehicle has been
absorbed. After the passage of shredders 116, one or
more energy absorbing elements 100 will be separated into
upper and lower parts (not expressly shown).
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The length of respective rows 188 and 189 associated
with energy absorbing system 20b may be selected to be
long enough to provide multiple stages for satisfactory
deceleration of large, high-speed vehicles after sled
assembly 40b has moved through a front portion with
"relatively soft" energy absorbing elements. Generally,
energy absorbing elements installed in the middle portion
of rows 188 and 189 and immediately adjacent to the end
of each row will be relatively "hard" as compared to
energy absorbing elements installed adjacent to first end
21.
Panel support frames 60a-60e may have substantially
the same dimensions and configuration. Therefore, only
panel support frame 60e as shown in FIGURE 17 will be
described in detail. Panel support frame 60e has a
generally rectangular configuration defined in part by
first post 68 disposed adjacent to guide rail 208 and
second post 69 disposed adjacent to guide rail 209. Top
brace 61 extends laterally between first post 68 and
second post 69. Bottom brace 62 extends laterally between
first post 68 and second post 69. The length of posts 68
and 69 and the location of bottom brace 62 are selected
such that when panel support frame 60e is disposed on
guide rails 208 and 209, bottom brace 62 will contact
guide rails 208 and 209 but posts 68 and 69 will not
contact concrete foundation 308.
A plurality of cross braces 63, 64, 65, 70 and 71
may be disposed between posts 68 and 69, top brace 61 and
bottom brace 62 to provide a rigid structure. For some
applications cross braces 63, 64, 65, 70 and 71 and/or
posts 68 and 69 may be formed from relatively heavy
structural steel components. Also, cross brace 65 may be
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installed at a lower position on posts 68 and 69. The
weight of support frames 60a-60e and the location of the
associated cross braces may be selected to provide
desired strength during a side impact with energy
absorbing systems 20, 20a, 20b or 20c.
Tab 66 may be attached to the end of post 69
adjacent to concrete foundation 308 and extends laterally
toward energy absorbing assemblies 86. Tab 67 is attached
to the end of post 68 adjacent to concrete assembly 308
and extends laterally toward energy absorbing assemblies
86. Tabs 66 and 67 cooperate with bottom brace 62 to
maintain panel support frame 60e engaged with guide rails
208 and 209 during a side impact with energy absorbing
system 20b to prevent or minimize rotation in a direction
perpendicular to guide rails 208 and 209 while allowing
panel support frame 60e to slide longitudinally toward
roadside hazard 310.
Impact from a vehicle colliding with either side of
energy absorbing assembly 20, 20a, 20b, or 20c will be
transferred from panels 160 to panel support frames 60a-
60g. The force of the lateral impact will then be
transferred from panel support frames 60a-60g to the
associated guide rails 208 and/or 209 to energy absorbing
assemblies 86 through cross ties 24 and mechanical
fasteners 26 to concrete foundation 308. Cross ties 24,
mechanical fasteners 26, energy absorbing assemblies 86,
guide rails 208 and 209 along with panel support frames
60a-60g provides lateral support during a side impact
with energy absorbing system.
When a vehicle initially impacts sled assembly 40b
facing oncoming traffic, any occupants who are not
wearing a seat belt or other restraining device may be
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catapulted forward from their seat. Properly restrained
occupants will generally decelerate with the vehicle.
During the short time period and distance sled assembly
40b travels along guide rails 208 and 209, an
unrestrained occupant may be airborne inside the vehicle.
Deceleration forces applied to the impacting vehicle
during this same time period may be quite large.
However, just prior to an unrestrained occupant
contacting interior portions of the vehicle, such as the
windshield (not expressly shown), deceleration forces
applied to the vehicle will generally be reduced to lower
levels to minimize possible injury to the unrestrained
occupant.
Portions of diagonal braces 148 and 149 and/or top
brace 141 of sled assembly 40b will contact panel support
frame 60a which will, in turn, contact panel support
frame 60b and any other panel support frames disposed
downstream from sled assembly 40b. Movement of sled
assembly 40b toward hazard 310 results in telescoping of
panel support frames 60a-60e and their associated panels
160 with respect to each other. The inertia of panel
support frames 60 and their associated panels 160 will
further decelerate an impacting vehicle as sled assembly
40b moves longitudinally from first end 21 toward second
end 22 of energy absorbing system 20b. The telescoping
or sliding of panels 160 against one another produces
additional friction forces which also contribute to
deceleration of the vehicle. Movement of panel support
frames 60a-60e along guide rails 208 and 209 also
produces additional frictional forces to even further
decelerate the vehicle.
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As previously discussed with respect to FIGURES 4A
and 4B, panel support frames 60a-60e and associated
panels 160 will redirect vehicles striking either side of
energy absorbing system 20b back onto an associated
5 roadway. Each panel 160 may a generally elongated
rectangular configuration defined in part by first end or
upstream end 161 and second end or downstream end 162.
(See FIGURES 5 and 7.) Each panel 160 preferably
includes first edge 181 and second edge 182 which extend
10 longitudinally between first end 161 and second end 162.
For some applications panels 160 may be formed from
standard ten (10) gauge W beam guardrail sections having
a length of approximately thirty-four and three-fourth
inches for "one-bay panels" and five feet two inches for
15 "two-bay panels." Each panel 160 preferably has
approximately the same width of twelve and one-fourth
inches.
As shown in FIGURES 5 and 7, respective slot 164 is
preferably formed in each panel 160 intermediate ends 161
20 and 162. Slot 164 is preferably aligned with and extends
along the longitudinal center line (not expressly shown)
of each panel 160. The length of slot 164 is less than
the length of associated panel 160. Respective slot
plate 170 may be slidably disposed in each slot 164.
25 The upstream end of each slot 164 preferably includes
enlarged portion or key hole portion 164a which will be
discussed later in more detail.
Metal strap 166 may be welded to first end 161 of
each panel 160 along edges 181 and 182 and the middle.
30 See FIGURE 8. For some applications metal strap 166 may
have a length of approximately twelve and one-fourth
inches and a width of approximately two and one-half
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inches. The length of each metal strap 166 is preferable
equal to the width of the respective panel 160 between
respective longitudinal edges 181 and 182. Mechanical
fasteners 167, 168, and 169 may be used to attach each
metal strap 166 with post 68 of associated panel support
frame 69. Mechanical fasteners 167 and 169 are
substantially identical. Metal straps 166 provide more
contact points for mounting end 161 of panels 160 to
respective panel support frames 60a-60f.
Recesses 184 may be formed in each panel 160 at the
junction between second end 162 and respective
longitudinal edges 181 and 182. (See FIGURE 7.)
Recesses 184 allow panels 160 to fit with each other in a
tight overlapping arrangement when energy absorbing
system 20b is in its first position. As a result,
recesses 184 minimize the possibility of a vehicle
snagging the sides of energy absorbing system 20 during a
"reverse angle" collision or impact.
For purposes of explanation, panels 160 shown in
FIGURE 7 have been designated 160a, 160b, 160c, 160d,
160e and 160f. The longitudinal edges of panels 160a-
160d are identified as longitudinal edges 18la-181d and
182a-182d, and the longitudinal edges of panel 160f are
identified as longitudinal edges 181f and 182f. Also,
for panels 160a, 160b, and 160d, ends 161 and 162 are
identified as ends 161a and 162a, ends 161b and 162b, and
ends 161d and 162d, respectively. Likewise, for panel
160c, the upstream end is identified as end 161c; and for
panel 160e, the downstream end is identified as end 162e.
Respective metal straps 166 may be attached to first end
161a and first end 161d to post 68 of panel support frame
60c. In a similar manner, respective metal straps 166
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are provided to securely attach first end 161b and 161e
to corner post 68 of panel support frame 60d. As shown
in FIGURES 8 and 9, bolt 168 extends through hole 172 in
respective slot plate 170 and a corresponding hole (not
expressly shown) in panel 160b.
As shown in FIGURE 9, slot plate 170 preferably
includes hole 172 extending therethrough. A pair of
fingers 174 and 176 extend laterally from one side of
slot plate 170. Fingers 174 and 176 may be sized to be
received within associated slot 164 of respective panel
160. Mechanical fastener 168 is preferably longer than
mechanical fasteners 167 and 169 to accommodate slot
plate 170. Each slot plate 170 and bolt 168 cooperate
with each other to securely anchor end 161 of an inner
panel 160 with the associate post 68 or 69 while allowing
an outer panel 160 to slide longitudinally relative to
the associated posts 68 or 69.
During some vehicle impacts panel support frames
60a-60e and associated panels 160 may move to a second
position such as shown in FIGURE 4B. As a result repair
and reassembly of energy absorbing system 20b may be more
difficult. However, enlarged portions 164a of slots 164
cooperate with associated slot plate 170 to allow the
respective panel 160 to be more easily released from the
associated panel support frame 60.
For some applications the length of enlarged portion
164a may be approximately equal to or greater than the
combined length of three slot plates 170. Enlarged
portions 164a and associated slot plates 170 cooperate
with each other to substantially reduce or eliminate many
binding and/or interference problems which may result
from an impacting vehicle moving an energy absorbing
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system from a first, extended position to a second,
collapsed position. See for example, FIGURES 4A and 4B.
Energy absorbing system 20c as shown in FIGURES
10-16 may include sled assembly 40c and multiple energy
absorbing assemblies 286 aligned in respective rows 288
and 289 extending generally longitudinally from a hazard
and generally parallel with each other. For some
applications each row 288 and 289 may contain two or more
energy absorbing assemblies 286. Energy absorbing
assemblies 286 in row 288 may be spaced laterally from
energy absorbing assemblies 286 in row 289. See FIGURES
12, 13 and 16.
Sled assembly 40c may have a modified configuration
similar to sled assembly 40b. Energy absorbing
assemblies 286 may be secured with each other by a
plurality of cross braces 24. Cooperation between cross
braces 24 and energy absorbing assemblies 286 results in
energy absorbing system 20c having a relatively rigid
frame structure. As a result, energy absorbing system
20c may be better able to absorb impact from a motor
vehicle that strikes sled assembly 40c offset from the
center of end 21 or that strikes end 21 at an angle other
than approximately parallel with energy absorbing
assemblies 286.
Energy absorbing assemblies 286 may be securely
attached to concrete foundation 308 in front of a hazard
using cross ties 24 and bolts 26 as described with
respect to energy absorbing system 20b and energy
absorbing assemblies 86. Cross tie attachments 300,
which will be discussed later in more detail, may be used
to securely engage energy absorbing assemblies 286 with
respective cross ties 24. Each row 288 and 289 of energy
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absorbing assemblies 286 may have a respective first end
287 which corresponds generally with first end 21 of
energy absorbing system 20c.
Sled assembly 40c may be disposed adjacent first end
287 of rows 288 and 289 with shredders 216 aligned with
respective energy absorbing assemblies 286 prior to a
vehicle impact. For embodiments represented by energy
absorbing system 20c shredders 216 may be disposed
generally vertical relative to sled assembly 40c, energy
absorbing elements 100 and an associated roadway (not
expressly shown). Each shredder 216 may be formed from a
bolt having a diameter of approximately one half of an
inch and a length of approximately eleven inches. The
same materials may be used to form shredders 216 as
previously described with respect to shredders 116. Each
energy absorbing element 100 may be disposed generally
horizontal relative to associated shredders 216 and the
roadway. See FIGURE 12.
A pair of ramps 32 may be provided at end 21 of
energy absorbing system 20c to prevent small vehicles or
vehicles with low ground clearance from directly
impacting first end 287 of rows 288 and 289. Various
types of ramps and other structures may be provided to
ensure that a vehicle impacting end 21 of energy
absorbing system 20c will properly engage sled assembly
40c and not directly contact first ends 287 of rows 288
and 289.
Each energy absorbing assembly 286 as shown in
FIGURES 10-15 may include a pair of supporting beams 290
disposed longitudinally parallel with each other and
spaced laterally from each other. Shredding zone 218 may
be formed by the resulting longitudinal gap between each
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pair of supporting beams 290. For some applications
supporting beams 290 may have a generally C-shaped cross
section as previously described with respect to
supporting beams 90 or any other satisfactory cross
5 section.
For applications such as shown in FIGURES 10-14,
supporting beams 290 may be described as angles having
generally L-shaped cross sections defined in part by
first leg 291 and second leg 292. Legs 291 and 292 may
10 intersect each other at an angle of approximately ninety
degrees. For some applications supporting beams or
angles 290 may be fabricated by using metal roll forming
techniques. The use of angles 290 may reduce inventory
requirements and cost of both manufacture and repair of
15 an associated crash cushion. For some applications
supporting beams 290 and guide rails 208 and 209 may be
formed from the same type of structural steel angle.
The L-shaped cross section of each supporting beam
290 may be disposed facing each other to define a
20 generally C-shaped or U-shaped cross section for each
energy absorbing assembly 286. For some applications the
width of leg 291 may be substantially longer than the
width of leg 292. For embodiments such as shown in
FIGURE 12, the width of each first leg 291 may be
25 approximately equal to the combined width of associated
second legs 292 plus the width of shredding zone 218. As
a result energy absorbing assembly 286 may have a
generally square cross section. See FIGURE 12.
A plurality of holes 98 may be formed in each second
30 leg 292 for use in attaching one or more energy absorbing
elements 100 with associated energy absorbing assembly
286. For some applications such as shown in FIGURE 15,
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the diameter of holes 98 may vary along the length of
each leg 292. For example, some holes 98b may have an
inside diameter selected to accommodate a typical 9/1611
bolt such as mechanical fasteners 250. Other holes 98a
may have a smaller inside diameter selected to
accommodate a 3/8" bolt or threaded stud with a 9/16"
diameter shoulder and no head such as mechanical
fasteners 260.
For purposes of describing various features of the
present invention energy absorbing elements 100
associated with energy absorbing assemblies 286 may be
designated as energy absorbing elements 100a, 100b, 100c
and 100d. For some applications energy absorbing
assemblies 286 may have approximately the same overall
length, width and height as previously described for
energy absorbing assemblies 86. Various types of
fasteners may be inserted through holes 98 in supporting
beams 290 and corresponding holes 108 formed in energy
absorbing elements 100.
A pair of energy absorbing elements 100d may be
disposed on each energy absorbing assembly 286 proximate
first end 21 of energy absorbing assembly 20c. See
FIGURES 11, 12 and 16. Energy absorbing elements 100d
are shown in dotted lines in FIGURE 10. The overall
length of energy absorbing elements 100d may be
substantially reduced as compared to energy absorbing
elements 100a, 100b and 100c. Slot 202 may be formed in
each energy absorbing element 100d to receive respective
shredder 216.
Dimensions associated with each shredder 216 are
preferably selected to be compatible with associated slot
202 and gap or shredding zone 218 formed between
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associated supporting beams 290. The dimensions may be
selected to allow each shredder 216 to slide
longitudinally between second legs 292 of associated
supporting beams 290. For embodiments such as shown in
FIGURES 10-16, energy absorbing elements 100d have a
relatively short length. However, the length of energy
absorbing elements 100d may be increased based on the
amount of energy absorption desired within the first
stage of an associated energy absorbing system.
A plurality of holes (not expressly shown) may be
formed along the length of each first leg 291 to allow
attaching guide rails 208 or 209 with associated
supporting beams 290. See for example FIGURES 10-13.
Various welding techniques and/or other mechanical
attachment techniques may also be satisfactorily used to
securely engage guide rails 208 and 209 with respective
energy absorbing assemblies 286. Guide rails 208 and 209
cooperate with each other to allow sled assembly 40c to
move longitudinally from first end 21 of energy absorbing
assembly 20c toward an associated hazard. First leg 211
of guide rails 208 and 209 may be attached to first leg
291 of associated supporting beams 270.
For some applications shredders 216 may be installed
as part of replaceable modules 220. As shown in FIGURES
10, 11 and 12 each module 220 may include respective
support plate 222 disposed between shredder 216 and
bottom brace 51. Support plates 222 are shown in dotted
lines in FIGURES 10 and 13. Respective pairs of angles
or brackets 228 and 229 may be attached with bottom brace
51 extending in the direction of associated rows 288 and
289. Each pair of angles 228 and 229 may be spaced from
each other to slidably receive respective module 220
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therein. For some applications the upper portion of each
module 220 may be enlarged with respective shoulders (see
FIGURE 10). As a result modules 220 may be inserted
between respective pairs of angles 228 or 229 with the
shoulders resting on the respective pair of angles 228 or
229.
For some applications support plates 222 may be
modified to have a blunt shredding surface formed on the
respective downstream edge facing respective energy
absorbing assemblies 286. For such embodiments the blunt
shredding surface may be formed as an integral component
(not expressly shown) of support plates 222. Support
plate 222 may be formed from substantially the same
materials as used to form shredders 216.
For some applications respective retainer lugs 240
may extend through openings (not expressly shown) in each
module 220 and associated brackets 228 or 229. See
FIGURE 12. Cotter pin 242 or similar devices may be used
to releasably engage retainer lug 240 with associated
module 220 and brackets 228 or 229. In the event of
failure or damage to shredder 216, associated cotter pin
242 may be removed to allow retainer lug 240 to be
disengaged from associated module 220 and respective
brackets 228 or 229. Module 220 may then be removed and
damaged shredder 216 replaced.
For some applications each shredder 216 may have
threads formed on opposite ends thereof to receive
respective nuts 232. See FIGURE 12. Support plates 220
may have appropriately sized openings to receive
respective shredder 216 therethrough. Nuts 232 may be
attached with the threaded portions of each shredder 216
to securely engage shredders 216 with associated support
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plates 222. Various other mechanisms and techniques may
be satisfactorily used to releasably engage shredders 216
with sled assembly 40c. The present invention is not
limited to modules 220, vertical support plates 222,
retainer lugs 240 or nuts 232.
Sled assembly 40c may be include corner posts 42 and
43 along with other features of previously described sled
assembly 40b. Top brace 141 and bottom brace 51
preferably extend laterally between corner posts 42 and
43. Bottom brace 51 may be disposed immediately adjacent
to second leg 212 of guide rails 208 and 209. See FIGURE
12. The dimensions and materials used to form bottom
brace 51 may be selected to provide substantial strength
for transferring of energy from an impacting vehicle to
shredders 216 and associated energy absorbing elements
100. The height of bottom brace 51 and the length of
legs 42 and 43 may be selected to provide substantial
clearance between the bottom of corner post 42 and 43
with respect to concrete foundation 308 and cross ties
24. See FIGURE 12. The dimensions of bottom brace 51
and the length of corner post 42 and 43 cooperate with
each other to reduce the possibility that any portion of
sled assembly 40c may contact cross ties 24 and/or
portions of anchor bolts 26. As a result, sled assembly
40c may often be reused after a vehicle impact.
For some applications such as shown in FIGURES 10,
11 and 12, a pair of hook shaped plates 268 and 269 may
be attached proximate the end corners 43 and 42.
Respective contact plates 266 may be attached to each
pair of hook plates 268 and 269. Hook shaped plates 268
and associated contact plates 266 may engage adjacent
portions of guide rail 208 to resist side impacts with
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sled assembly 40b and maintain sled assembly 40b slidably
disposed on guide rails 208 and 209. Hook shaped plates
269 and associated contact plate 266 may engage adjacent
portions of guide rail 209 for similar purposes and
5 functions.
Gussets may be disposed between corner posts 42 and
43 and bottom brace 51 to provide additional structural
support. One or more reinforcing braces or angles (not
expressly shown) may be disposed on bottom brace 51 and
10 adjacent to portions of modules 220.
A pair of braces 148 and 149 may extend diagonally
from top brace 141 to a position immediately above guide
rails 208 and 209. Braces 48 and 49 may extend
longitudinally from bottom brace 51 and engage diagonal
15 braces 148 and 149 proximate respective guide rails 208
and 209. For some applications horizontal braces 48 and
49 may be formed from angles. Cross braces 143 and 144
may be securely engaged with horizontal braces 48 and 49
in a generally X-shaped pattern. Horizontal brace 145
20 may be disposed between diagonal braces 148 and 149.
Guide assemblies 58 and 59 may be attached with
respective ends of diagonal braces 148 and 149. Guide
assemblies 58 and 59 and guides 54 may have similar
features and characteristics. Guide assemblies 58 and 59
25 may be formed from an angle having dimensions compatible
with associated guide rails 208 and 209. Guide
assemblies 58 and 59 cooperate with each other to allow
sled assembly 40c to slide longitudinally along guide
rails 208 and 209 in the direction of an associated
30 hazard.
Guide assemblies 58 and 59 may include respective
first legs 57 which extend downwardly relative to
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associated guide rail 208 and 209. Legs 57 cooperate
with each other to maintain sled assembly 40c disposed on
guide rails 208 and 209 and shredders 216 aligned with
respective shredding zones 218 during a vehicle impact
while at the same time allowing sled assembly 40c to
slide longitudinally along guide rails 208 and 209
towards an associated hazard. Legs 57 cooperate with
each other to limit undesired lateral movement of sled
assembly 40c in response to a side impact. The inertia
of sled assembly 40c and friction associated with guide
assemblies 58 and 59 and bottom brace 51 sliding over
legs 212 of guide rails 208 and 209 will contribute to
deceleration of an impacting vehicle.
A plurality of mechanical fasteners may be used to
securely engage energy absorbing elements 100 with
associated supporting beams 290 to form energy absorbing
assemblies 286. By installing energy absorbing
assemblies 286 with associated energy absorbing elements
100 in a generally horizontal orientation relative to
other components of energy absorbing system 20c and an
associated roadway, the mechanical fasteners may be more
readably accessible for replacing damaged components and
installing new components. See FIGURE 13.
For example, bolts 250 and associated nuts 252 may
be used to securely engage one or more energy absorbing
elements 100 with respective supporting beams 290. A
plurality of headless bolts 260 may also be used to
releasably secure energy absorbing elements 100 with
associated supporting beams 290. Dimensions associated
with headless bolts 260 and corresponding openings 108 in
associated energy absorbing elements 100 may be selected
such that energy absorbing elements 100 may be installed
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and removed after disengagement of the mechanical
fasteners 250 and without disengagement of headless bolts
260. For embodiments such as shown in FIGURES 14 and 15,
bolts 250 and washers 254 may be removed to allow
disengagement of doublers 114 and associated energy
absorbing elements 100a and 100c. Nut 252 will
preferably remain securely engaged with associated nut
retainer 280.
For some embodiments of the present invention such
as represented by energy absorbing system 20c, each
energy absorbing element 100 may have a generally
elongated rectangular configuration defined in part by
first longitudinal edge 121 and second longitudinal edge
122. See FIGURES 15 and 16. A first row of openings 108
may be formed in each energy absorbing element 100
adjacent to first longitudinal edge 121. A second row of
openings 108 may be formed in each energy absorbing
element 100 adjacent to respective second longitudinal
edge 122. A third row of openings 110 with lands 112
disposed therebetween may be formed in each energy
absorbing element 100 between the first row of openings
108 and the second row of openings 108. See FIGURES 15
and 16.
For some applications energy absorbing system 20c
may have a relatively soft first stage, a second stage
having increased energy absorbing capability and a third
stage designed to absorb the energy of a high speed
and/or heavy vehicle. The length of energy absorbing
elements 100d in the first stage may be increased and/or
decreased to vary the amount of energy absorbed during
initial impact of a vehicle with sled assembly 40c.
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The second stage of energy absorbing system 20c may
include energy absorbing elements 100a with variable
spacing between associated openings 110 and associated
lands 112. For embodiments such as shown in FIGURE 16
the first portion of each energy absorbing element 100a
may include openings 110 having a diameter of
approximately one inch with a spacing of approximately
two inches between the centers of adjacent openings 110.
The middle portion of each energy absorbing element 100a
may include openings 110 having a diameter of
approximately one inch and a spacing of approximately two
inches between centers of adjacent openings 110. As a
result, the length of segments 112a in the first portion
of each energy absorbing element 100a may be
approximately one inch. Each segment 112b in the middle
portion of energy absorbing element 100a may have a
length of approximately two inches.
When a vehicle initially impacts sled assembly 40c a
portion of the vehicle's energy will be absorbed in the
first stage. When shredders 216 engage energy absorbing
elements 100a, the amount of energy absorbed by segments
112a may increase as compared with the first stage
(energy absorbing elements 100d) but may remain at a
lower value as compared with energy absorbed by segments
112b. The increased length of segments or lands 112b
results in increased deceleration as compared with the
shorter segments 112a. Therefore, substantial amounts of
energy may be absorbed as shredders 216 move through the
middle portion of respective energy absorbing elements
100a.
As an impacting vehicle starts to slow down, less
energy absorption may be desired to prevent an
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unrestrained occupant from impacting portions of the
vehicle. Therefore, the spacing between holes 110 in the
third portion or last portion of each energy absorbing
element 100a may be reduced. For example, segments 112c
may have approximately the same length as segments 112a
or the length of segments 112c may be even more reduced
as compared with the length of segments 112a.
For many vehicle impacts, most of the energy
absorption may occur in stages one and two. However, for
very high speed and/or heavy vehicles, shredders 216 may
engage energy absorbing elements 100b in stage three.
For some applications the thickness of energy absorbing
elements 100b in stage 3 may be substantially increased.
Alternatively, the spacing between holes 110 in stage 3
may be substantially increased. Teachings of the present
invention allow modifying energy absorbing elements 100
to provide desired deceleration for a wide variety of
vehicles traveling at a wide variety of speeds without
resulting in injury to an unrestrained occupant of the
vehicle.
For some applications two or more energy absorbing
elements 100 may be disposed on second leg 292 of each
supporting beam 290. For embodiments such as shown in
FIGURE 14, the thickness of energy absorbing elements
100a and 100c may vary. Also, the spacing between
respective openings 110 and/or the size of openings 110
formed in each energy absorbing element 100a and 100c may
be varied.
As previously noted the present invention allows
reducing the number of mechanical fasteners which must be
engaged and disengaged during replacement of a ruptured
or shredded energy absorbing element 100. As shown in
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FIGURES 14 and 15 one or more headless mechanical
fastener or headless bolts 260 may be disposed between
respective mechanical fasteners 250. For some
applications doublers or strong backs 114 may be disposed
5 on energy absorbing elements 100 opposite from second leg
292 of associated support beam 290. Doublers or strong
backs 114 improve the holding force of associated
mechanical fasteners 250 while at the same time
accommodating the use of headless bolts 260. For some
10 applications such as shown in FIGURE 13, pairs of
doublers, designated 114a-114h, may be used to securely
engage respective energy absorbing elements 100 with
associated energy absorbing assemblies 286. Each doubler
114 preferably includes holes 124 corresponding in
15 diameter with associated holes 108 formed along the
longitudinal edges 121 and 122 of each energy absorbing
element 100. Holes 124 formed in doublers 114 are
preferably selected to accommodate both bolts 250 and
headless bolts 260.
20 Various techniques and procedures may be
satisfactorily used to manufacture and assemble energy
absorbing assemblies in accordance with teachings of the
present invention. For example, energy absorbing
assemblies 286 such as shown in FIGURES 13, 14, 15 and 16
25 may be manufactured and assembled by forming supporting
beams 290 having a plurality of holes 98a and 98b
extending through each leg second 292. For embodiments
such as shown in FIGURES 13, 14, 15 and 16 three small
holes 98a may be disposed between adjacent larger
30 diameter holes 98b. Energy absorbing elements 100 and
doublers 114 which may be releasably attached with each
second leg 292.
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Headless bolts 260 may be inserted through
respective small diameter holes 98a. Shoulder 264 on
each headless bolt 260 will preferably engage adjacent
portions of second leg 292. Respective nuts 262 may be
engaged with the threaded portion of each headless bolt
260 extending through second leg 292. One or more energy
absorbing elements 100 may be placed or stacked on
respective second legs 292 by inserting headless bolts
260 through associated holes 108. Doublers 114 will also
be placed on respective energy absorbing elements 100 by
inserting headless bolts 260 through associated holes
124. Respective mechanical fasteners 250 may then be
inserted through associated openings 124 in doublers 114,
openings 108 in energy absorbing elements 100 and large
diameter opening 98b in associated second leg 292.
Washer 254 may be disposed between the head of bolt 250
and doubler 114. Nut 252 may then be securely engaged
with each bolt 250 to securely attach energy absorbing
elements 100a and 100c with respective supporting beams
290. Doublers 114 effectively increase the "holding
power" of associated bolts 250 and nuts 252.
For some applications such as shown in FIGURES 14
and 15 respective nut retainers 280 may be disposed on
each second leg 292 opposite from energy absorbing
elements 100. Each nut retainer 280 preferably includes
at least one opening with respective nut 252 disposed
therein. Nut retainer 280 allows associated mechanical
fastener 250 to be engaged and disengaged without having
to hold nut 252. Therefore, when energy absorbing
assembly 286 is disposed with energy absorbing elements
100 in a generally horizontal position, engagement with
only the head of mechanical fastener 250 is required to
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engage and disengage mechanical fastener 250 from
respective nut 252.
Nut retainers 280 may be formed with various
configurations and orientations. For some applications
nut retainer 280 may include one or more welded
attachments (not expressly shown) to secure each nut 252
aligned with respective opening 98b. For other
applications each nut retainer 280 may include a
generally rectangular plate 282 with a first opening 284
and second opening 286 formed therein. First opening 284
may be selected to receive associated nut 252. Second
opening 286 is preferably smaller than first opening 284.
Second opening 286 may be sized to receive the threaded
portion of associated headless bolt 260. Keeper plate
296 may be attached to nut retainer 280 opposite from
second leg 292 of supporting beam 290. Keeper plate 296
may also include first hole 298 sized to receive the
threaded portion of associated mechanical fastener 250
and second hole 299 sized to receive the threaded portion
of headless bolt 260. For some applications retainer
plate 282 and keeper plate 296 may be installed on
associated headless bolt 260 prior to engaging nut 262
with the respective threaded portion. Hole 298 of each
keeper plate 296 with nut 252 disposed therein is
preferably aligned with associated large diameter hole
98b in second leg 192 of associated supporting beam 290.
Hole 299 in each keeper plate 296 is preferably aligned
with associated smaller diameter hole 98a in second leg
192 of associated supporting beam 290.
For some applications energy absorbing elements 100d
may be attached to associated supporting beams 290 by
four mechanical fasteners bolts 250 and no doublers.
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Energy absorbing element 100a may be attached to
associated supporting beams 290 by eight doublers and
twenty four mechanical fasteners 250. Energy absorbing
elements 100b may also be attached to associated
supporting beams 290 by eight doublers and twenty four
mechanical fasteners 250. For some applications the
length of energy absorbing system 20c may be increased by
adding more energy absorbing assemblies 286.
Various types of mechanisms may be satisfactorily
used to engage energy absorbing assemblies 286 with cross
ties 24. For embodiments such as shown in FIGURE 14,
each cross tie attachment 300 may have the general
configuration of an angle defined in part by legs 301 and
302. A plurality of mechanical fasteners 304 may be
disposed between openings formed in leg 301 and securely
engaged with corresponding holes (not expressly shown)
formed in first leg 291 of associated supporting beam
290. Second leg 302 of each cross tie attachment 300 may
be welded or otherwise securely attached with associated
cross tie 24.
Technical benefits of the present invention may
include providing modular base units which may be
preassembled prior to delivery at a roadside location.
For some applications each modular base unit may include
rows 188 and 189 or rows 288 and 289, sled assembly 40b
or 40c and panel support frames 60a-60g with panels 160
installed in their first position. The use of a modular
base unit may minimize repair time at a roadway location
and allow for more efficient, cost effective repair of a
damaged modular base unit at an off site repair facility.
Energy absorbing assemblies 86 or 286 and shredders
116 and 216 may also be used in a wide variety of movable
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applications such as truck mounted attenuators. The
present invention is not limited to relatively fixed
applications such as represented by energy absorbing
system 20, 20a, 20b and 20c. For truck mounted
attenuators, such as described in U.S. Patent No.
5,947,452, energy absorbing assemblies 86 or 286 may be
attached to and extend rearwardly from a truck or other
vehicle (not expressly shown). An impact head (not
expressly shown) may be provided at the end of energy
absorbing assemblies 86 or 286 opposite from the truck or
other vehicle. Respective shredders 116 or 216 may be
mounted on the truck or other vehicle opposite from the
impact head. Each shredder 116 or 216 may be aligned
with respective energy absorbing assembly 86 or 286 as
previously shown. When a second vehicle contacts the
impact head, the shredders will remain fixed relative to
the energy absorbing assemblies as the energy absorbing
assemblies move past the respective shredders. The
shredders operate as discussed above and energy is
dissipated so that the second vehicle is slowed and then
stopped.
Although the present invention has been described in
detail, it should be understood that various changes,
substitutions and alterations can be made hereto without
departing from the spirit and scope of the invention as
defined by the appended claims.
