Note: Descriptions are shown in the official language in which they were submitted.
3~
HIGHWAY BARRIER
BACKGROU~ OF THE INVENTION
... . _
The invention relates generally to systems
for absorbing and dissipating the impact energy of auto-
mobiles or other moving vehicles. More particularly,
the invention relates to an improved highway barrier
which will redirect the nose of an impacting vehicle
away from a roadside hazard while at the same time dis-
sipating kinetic energy of the impacting vehicle.
Rigid guardrails are usually positioned along
side vehicular traffic routes, especially highways, to
prevent vehicles from colliding with ~ixed objects,
other vehicles or from leaving the road. To this end,
the guardrails must be rigid enough to prevent the later-
al movement of an impacting vehicle. While guardrails
function to prevent vehicles from impacting unyielding
objects, they themselves may present a hazard to a vehi-
cle impacting the end portion of the unyielding guardrail.
Energy attenuation and absorbing devices for
highway abutments are known in the art. An example of
such a unit is United States Patent No. 4,352,484 to
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:
--2--
Gertz, et al. These dev.ices are utilized to ~.is~ipate
the impact energy of a vehicle. To this end, thes~
barriers usually include a deformable structure or ma-
terial which dissipates the energy of an impacting
vehicle as it is crushed. Despite the success of ~hese
devices they are typically too expensive to be u~ed to
prevent vehicles from impacting guardrails.
Highway barriers have been developed for use
with the end portions of guardrails. An example of
these prior art devices are fender panels which are
designed to telescope upon the application of an axial
impact force. These prior guardrail barriers typically
have difficulties dissipating the energy of large vehi-
cles or vehicles traveling at high speeds. When these
devices are impacted at high speeds, the fastening mem-
bers are sometimes pulled through the panels causing
the panels to separate and failing to telescope. Fur-
thermore, if the telescoping panels do not dissipate a
sufficient amount of the energy the impacting vehicle
will hit the unyielding portion of the guardrail after
the panels have telescoped. This can result in the
fender panels of the guardrail spearing the car and
seriously injuring its occupants.
Breakaway cable terminals are also used to
dissipate the energy of a vehicle impacting the end
portion of a guardrail. Basically, a breakaway cable
terminal is a cable which extends from the first verti-
cal support leg to a fender panel at a position in front
of the second vertical support leg. Upon impact, the
first vertical leg is designed to breakaway, thereby
releasing the cable and minimizing the spearing forces.
This design has had difficulty in preventing light weight
vehicles travelling at high speeds from being speared
by a fender panel upon axial impact with the ~uardrail.
~3~:~55
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SUMMARY OF THE INVENTION
The present invention is directed to an im-
proved highway barrier which redirects an impacting
vehicle away from a roadside hazard.
According to this invention, a highway bar-
rier is provided for protecting an impacting vehicle
from colliding with a roadside structure positioned
alongside a roadway. This barrier comprises a beam
having a forward and a rearward end. The rearward end
of the beam is rotatably mountecl to the roadside struc-
ture such that the beam is rotatable away from the
roadway. A collapsible guardrail assembly is mounted
to the forward end of the beam. This assembly includes
a plurality of panels and means for mounting the panels
together such that the panels extend alongside the road~
way and adjacent panels are slidable with respect to
one another to allow the panels to telescope together
when struck by the impacting vehicle. The panels are
supported by means which allow the panels to telescope
together when struck by the vehicle. The guardrail
assembly is effective to deflect the impacting vehicle
away from the roadway as the yuardrail assembly tele-
scopes together when struck by the impacting vehicle.
The beam is effective to deflect the impacting vehicle
farther away from the roadway and the roadside struc-
ture as the beam rotates with respect to the roadside
structure.
In the past, beams have been rotatably mount-
ed to a roadside structure so as to redirect an impac-
ting vehicle away from the structure. However, when asimple rigid beam is used without the collapsible guard-
rail assembly described above, there is a tendency for
the beam to fail to rotate when the vehicle is approach
ing the beam axially. When this happens, the beam
~91~35S
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provides a rigid barrier which can do considerable dam-
age to the vehicle and can injure the occupants of the
vehicle. It has been discovered that the collapsible
guardrail assembly described above cooperates with the
rotatable beam to reduce the likelihood that the beam
will spear the impacting vehicl.e. In particular, the
collapsible guardrail assembly deflects the impacting
vehicle away from the roadway as it telescopes togeth-
er. In many cases, the impacting vehicle is deflected
sufficiently by the collapsing guardrail assembly such
that the vehicle either misses the rotatable b~arn en-
tirely or strikes the rotatable beam at a sufficient
angle to cause the beam to begin to rotate, thereby
deflecting the impacting vehicle farther away from the
roadway. Thus, the guardrail assembly cooperates with
the rotatable beam to provide a markedly improved high-
way barrier.
The invention itself, together with further
objects and attendant advantages, will best be under-
stood by reference to the fol.lowing detailed descrip-
tion, taken in conjunction with the accompanying draw-
ings.
3RIEF D~SCRIPTION OF THE DRAWINGS
.. _
Figure 1 is a plan view of a first preferred
embodiment of a guardrail end terminal.
Figure la is a side elevation view of a sand
saddle utilized in the guardrail end terminal of Figure 1.
Figure 2 is a side elevation view of the
guardrail end terminal of Figure l.
Figure 3 is a cross-sectional view taken along
line 3-3 of Figure 2.
Figure 4 is a side elevation view of a por
tion of the guardrail end terminal of Figure 1.
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~ X~ 3S~
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Figure 5 is a cross-sectional view taken along
line 5-5 of Figure 4.
Figure 6 is a cross-sectional view taken along
line 6-6 of Figure 4.
Eigure 7 is a side ele~ational view in partial
cutaway of a slip base included in the guardrail end
terminal of Figure 1.
Figures 8a-8f are a series of schematic plan
views which illustrate the lateral pole vaultiny effect
of the guardrail end terminal of Figure 1.
Figure 9 is a side elevation of a highway
barrier which incorporates a second preferred embodi-
ment of this invention.
Figure 10 is a plan in partial section taken
along line 10-10 of Figure 9.
Figures lla-llf are six consecutive plan views
showing the operation of the embodiment of Figures 9
and 10 when struck by an impacting vehicle.
Figures 12a and 12b are consecutive plan views
showing a second mode of operation of the embodiment of
Figures 9 and lO when struck by an impacting vehicle.
-~` Figure 13 is a partial side elevation of a
highway barrier which lncorporates a third preferred
embodiment of this invention.
Figure 14 is a plan in partial section taken
along lines 14-14 of Figure 13.
Figure 15 is a plan corresponding to Figure
14 showing the beam in a rotated position after impact
by a vehicle.
DETAILED DESCRIPTION OF T~E PREFERRED EMBODIMENTS
The First Preferred Embodiment
The first preferred embodiment is shown in
FIGS. 1-8f, and it include a plurallty of nested
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fender panels which telescope in response to an axial
impact force and a cable for urging a first fender
panel laterally upon the application of the axial
impact force. The fender panels and cable function to
direct the nose of the impacting vehicle away from a
hard point on the guardrail while at the same time dis-
sipating the impact energy of the vehicle.
The fender panels of this first embodiment
are slotted and secured together in a nested fashion by
fasteners which allow the fender panels to telescope
upon the application of an axial impact force. The
fender panels are supported above the ground on verti-
cal support legs which are positioned on slip bases
whi~h allow the legs to break away from ground anchors
so that the fender panels may telescope.
The first fender panel of this first embodi-
ment and more specifically its vertical support leg is
connected to a cable which is anchored to a front cable
anchor located in front of the fender panels and a rear
cable anchor located perpendicular to the guardrail.
The cable is positioned so that when an axial impact
force starts the first panel telescoping the cable will
urge the fender panel laterally. This will cause a
"lateral pole vaulting effect" which will urge the vehi-
cle away from the hard point on the guardrail.
This first preferred embodiment provides impor-
tant advantages in that it both dissipates kinetic energy
of the impacting vehicle and redirects the vehicle away
from the hard point. Thus the vehicle is both slowed
and shifted laterally, and in many cases the vehicle is
prevented from colliding with the hardpoint even though
the vehicle is not brought to a rest before the hard
point.
Turning now to the drawings, Figure 1 illus-
trates a plan view of the first preferred embodiment of
1~3~355i
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the guardrail end terminal lO. The guardrail end ter-
minal 10 is attached to and acts as the end portion of
a guardrail 12. The guardrail end terminal 10 is de-
signed to prevent vehicles from impacting head on the
hard point 14 of the guardrail 12. The hard point 14
of the guardrail 12 is that portion of the guardrail
which is not designed to yield upon impact with a vehi-
cle. As will be described in greater detail below, the
guardrail end terminal 10 is designed to redirect the
front end of an impacting vehicle away from the hard
point 1~ while at the same time dissipating the eneryy
of the impact force of the vehicle.
Referring now to Figures 2 and 4, the guard-
rail end terminal 10 includes a plurality of nested
fender panel~ 18. The fender panels 18 include slots
20 and are secured together by a plurality of fastener
members 22 which allow the fender panels to telescope
upon the application of an axial impact force.
The fastener members 22 are designed to en-
gage the slot 20 of one of the fender panels 18 and anaperture 21 of a second fender panel 18. By way of
example, Figure 3 illustrates the attachment of two
fender panels 18a and 18b by a fastener member 22. The
fastener member 22 includes a plate member 23 and a
bolt 26. The plate member 23 has a preferably rectan-
gular shape which conforms to the surface of the fender
panel 18a, and thereby includes curved ends 31 and 33.
The plate member 23 further includes a funnel shaped
aperture 27 which leads to a neck portion 29. The aper-
ture 27 and neck portion 29 are designed to receive abolt 26. To this end, the bolt 26 includes a head 30
which conforms to the shape of the aperture 27 of the
plate member 23.
The plate member 23, and more specifically
the neck portion 29, is designed to be received within
~;~'31355
a slot 20 in a first fender panel 18a and rest on the
shoulders 62 which surround an aperture 21 in the sec-
ond fender panel 18b. Once so received, the plate member
23 is secured on a side of the fender panel 18a by the
bolt 26 which is received within the aperture 27 and
then secured in place by a washer 64 and nut 88.
The fastener member 22 is constructed so that
it does not clamp the two fender panels 18a and 18b
together but rather secures them in juxtaposition to
one another with a sufficient tolerance to allow the
first fender panel 18a to telescope into the second
fender panel 18b. Because of the construction of the
fastener member 22 and specifically the plate member
23, when a sufficient axial impact force is applied to
the first fender panel 18a the fastener member 22 will
ride in slot 20 allowing the panel 18a to move axiall~
with respect to the second fender panel 18b in a tele-
scoping fashion. The axial movement of the first fender
panel 18a will only be impeded upon the end of the slot
20 reaching the fastener member 22.
The funnel shape of the aperture 27 in the
plate member 23 and shape of the head 30 of the bolt 26
prevent the bolt 26 from being pulled through the slot
20 when the fender panels 18 are telescoping in re-
sponse to an axial impact force. Thus, when an axialimpact force is applied to the fender panels 18 the
fastener members 22 allow the panels to telescope along
the slots 20.
The fender panels 18 are supported above the
ground 42 by vertical support legs 28. Preferably, the
support legs 28 are steel I Beams. In the preferred
embodiment illustrated in the drawings, the vertical
support legs 28 are bolted to a blockout 30 which is
bolted to the fender panels 18. The blockouts 30 pre-
vent automobiles with small wheels from snagging on the
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355
verti.cal support legs 28 when they impact the guardrail
end terminal 10 at a glancing angle. The blockouts 30
are also preferably steel "I Beams."
As shown in Figures 4 and 5, the vertical
support legs 28 are secured to a slip base 30. The
slip base 30 includes a top plate 32 and a bottom plate
34 which are secured to each other. The bottom plate
34 is fastened, as for example by welding or bolting,
to a ground anchor 70. Various types of ground anchor
constructions 70 are known in the art. By way of
example, the ground anchor 70 may include a steel rect-
angular tubing 72 which is plugged into a concrete foot-
ing 74 to securely position it in the ground 42. The
top plate 32 is welded to the vertical support leg 28.
Referring now to Figures 5 and 7, the top and
bottom plates 32 and 34 each include four slots 36,
each slot being designed to receive a bolt 38 which
secures the plates 32 and 34 together. The plates 32
and 34 are large enough so that they will not yield
upon a lateral impact force. The slots 36 are open
ended so that when a sufficient axial impact force is
applied to the vertical support leg 28 the plates 32
and 34 will slide apart, as illustrated in Figure 7.
To insure that the plates 32 and 34 will slip apart the
plates 32 and 34 are separated by four washers 39. The
washers 39 define the area at which the plates 32 and
34 are joined so that the force needed to cause the
plates 32 and 34 to slide apart can be controlled. It
has been found that if the plates 32 and 34 are boltad
together at 60 foot-pounds (8.28 Kg-m) sufficient ener-
gy will be dissipated by the slip bases.
~s shown in Figure 5, the vertical support
legs 28 may include an angle plate 68. The angle plate
68 is attached to the front of the top plate 32 and
helps to prevent the support legs 28 from becoming hung
;355
-10--
up on each other as they breakaway in response to an
axial impact force. Because there is no vertical sup-
port leg 28 to collapse into it, the first vertical
support leg 28a does not include an anyle plate 68.
Referring now to Figures 1, 4 and 6, the
first vertical support leg 28a is of substantially the
same construction as the other vertical support legs 28
except that it contains an aperture 40. The aperture
40 is located in the lower portion of the leg 28a and
is designed to receive a cable 48. As shown in Fiyure
2, the ~able 48 extends from a front cable anchor 46
through the aperture 40 in the first vertical support
ley 28a to a rear cable anchor 50. As will be described
in detail below, the cable 48 urges the first fender
panel 18a laterally upon the application of an axial
impact force.
The rear cable anchor 50 is located perpen-
dicular to the guardrail 12 and includes an earth anchor
56 and rod 58. Preferably, the ground anchor 56 is a
typical concrete anchor. The rod 58 is secured within
the ground anchor 56 and is designed to secure an end
of the cable 48. The front cable anchor 46 is located
in front of the first vertical support leg 28a and also
includes a ground anchor which secures the front end of
the cable 48. The cable 48 is passed through the aper
ture 40 in the first vertical support leg 28a and then
secured to the front and rear cable anchors 46 and 50.
Thus, the cable 48 extends from the front
cable anchor 46 through the first vertical support leg
28a to the rear cable anchor 50. Because the rear cable
anchor 50 is located perpendicular to guardrail 12 the
cable 48 extends from the front first vertical support
leg 28a at an acute angle to the guardrail end terminal
lO. As shown in Figure 6, to insure that the cable 48
extends from the first vertical support leg 28a at the
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~;~'3~L3~
proper angle and to prevent the cable from wearing
through on the leg 28a a sleeve 59 extends from the
aperture 40 on each of its sides and receives the cable
48. The sleeve 59 also helps to dissipate the energy
of an impacting vehicle by being dragged down the cable
48 during impact and thereby exerting a deacceleration
force.
The cable 48 provides redirectioning to a
vehicle which impacts the guardrail end terminal 10
head on. To this end, the cable 48 is designed to urge
the first fender panel 18a la~erally upon application
of an axial impact force. By urging the first fender
panel 18a laterally, the cable 48 causes, as will be
described in more detail below, a "lateral pole vault-
ing effect" on the panels 18. The cable 48 is preferably
constructed from steel and is sized such that it will
stretch to about 1 to 1-1/2% its length upon applica
tion of an impact force. By experimentation it has
been found that a steel cable 48 with a diameter of 7/8
of an inch (2.2225 cm) is sufficient to urge the panels
18 laterally.
Referring now to Figures 8a-8f, the lateral
pole vaulting effect of the guardrail end terminal 10
is illustrated. When a vehicle impacts the guardrail
end terminal 10 head on, the first panel 18a is forced
backwards telescoping into the second panel 18b. To
this end, the first panel 18a slides axially along the
fastening member 22. As the vehicle continues its mo-
tion, it impacts a second vertical support leg 28a
causing the top plate 32 of the second slip base 30 to
slip away from the bottom plate 34.
The rearward movement of the first panel
stretches the cable 48 until the cable will not stretch
any further (approximately 1 to 1-1/2% of its length).
The cable 48 then urges the first panel 18a laterally
3S~.
12-
causing -the first fender panel 18a to give a small
lateral impulse to the nose of the impacting vehicle.
As the first fender panel 18a reaches the end of its
travel the second fender panel 18b begins to telescope
i.nto the third fender panel 18c. The first fender
panel 18a will reach the end of its axial movement be-
fore the second slip base 30b can break free. Each
slip base 30 dissipates some of the energy of the
impacting vehicle. This process continues until all
the fender panels 18 of the guardrail end terminal 10
have broken free giving a large lateral force to the
impacting vehicle causing it to be directed away from
the hard point 14.
Because the slip bases 30 may not remove a
sufficient amount of energy to keep an impacting vehi-
cle from hitting the hard point 14, the guardrail end
terminal 10 may include sand saddles 60. The sand
saddles 60 are containers which are filled with a de-
sired amount of sand 78. As illustrated in Figure la,
each sand saddles 60 includes two containers 74 and 76.
Each container 74 and 76 includes a bolt 72 which allows
the two containers to be attached to each other to form
the sand saddle 60. The containers 74 and 76 have a
construction that conforms to the blockouts 30 and I
Beams 28. The sand saddle 60 also includes a lid 70
which snaps over the two containers 74 and 76.
It has been found that by adding about 200-
300 pounds (90-135 Kg~ of sand to the sand saddles 60,
the energy of most impacting vehicles i~ sufficiently
reduced, through momentum transfer to the sand, to
allow the guardrail end terminal 10 to redirect the
impacting vehicle and thereby prevent the vehicle from
impacting the hard point 14. Preferably, the first two
sand saddles 60 are filled with 200 pounds (90 Kg) of
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1~9~L3~S
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sand and the third sand saddle is filled with 300 pounds
(135 Kg) of sand.
By adjusting the angle at which the cable 48
extends away from the first fender panel 18a, the mass
of the vehicle that can be redirected can be increased.
But, it should be noted that the greater the angle of
the cable 48, the more unyielding the guardrail end
terminal 10 will be. It has been found that an angle
of approximately 25 redirects most road vehicles away
from the hardpoint 14 of the yuardrail 12 while at the
same time providing a guardrail end terminal 10 which
is sufficiently yielding to protect the occupants of
most impacting vehicles.
The first fender panel 18a may include a bull
nose 57. The bull nose 57 provides a curved area for
an impacting vehicle to hit instead of a pointed fender
panel 18.
Referring now to Figures 1 and 2, the guard-
rail end terminal 10 may be used with a standard anchor
cable system. The standard anchor cable system includes
a second cable 82 which extends from the ground anchor
46 of a vertical support leg 28 to a transition fender
panel 84 in the guardrail 12. The transition fender
panel 84 is connected to the last fender panel 18e of
the guardrail end terminal 10 and the hard point 14 of
the guardrail 12. The second cable 82 is received
within a rectangular block 86 which is attached to the
transition fender panel 84.
The Second And Third Preferred Embodiments
The second and third preferred embodiments of
Figures 10-15 both include a collapsible guardrail assem-
bly, substantially identical to that described above in
conjunction with Figures 1-8, in combination with a
beam which is rotatably mounted to a roadside hazard.
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~X~3;~ 5.5
-14-
Turning now to Fiyures 9-12b, the second
preferred embodiment includes a highway barrier 100
which is mounted alongside of and generally parallel to
a roadway as shown in Figure 10. The highway barrier
100 is provided to protect vehicles which leave the
roadway from colliding with a roadside hazard such as a
pole 102.
The barrier 100 includes a beam assembly 110
which is rotatably mounted to the pole 102. This beam
assembly 110 includes a rigid beam 112 which may, for
example, be a Thrie beam of the type described above in
conjunction with the first embodiment. A steel band
114 is mounted around the pole 102 to encircle the pole
102, and the rearward end of khe beam 112 is fastened
securely to the band 114 by fasteners 116. A riyid
brace 118 is provided which includes a forward flange
120 that is rigidly bolted to the beam 112 by fasteners
124 as well as a rearward flange 122 which is rigidly
secured to the band 114, as for example by welding. A
collar 126 is rigidly secured to the pole 102, and the
collar 126 supports the band 114 in vertical position,
without interfering with the freedom of the band 114 to
rotate about the pole 102. A tubular spacer 128 is
mounted withln the band 114 between the pole 102 and
the brace 113. The spacer 128 is sized to be more
readily deformed than the pole 102 such that the spacer
128 will deform before the pole 102 during the impact
of a vehicle. The band 114 can be formed for example
of steel of 1/4 to 3/4 inch thickness and should
preferably be strong enough to ensure that the beam
112 remains rotatably mounted to the hazard 102 during
normal operation of the highway barrier 100. The
spacer 128 is typically formed of steel tubing of 1/8
to l/2 inch in wall thicknass.
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1~3~ S
-15-
The barrier 100 also includes a collapsible
guardrail assembly 140. This yuardrail assembly 140 is
quite similar to that described above in conjunction
with the first preferred embodiment and includes an
array of axially extending overlapping panels 142.
Each of the panels 142 defines an axially extending
slot 144 positioned between the respective forward end
146 and rearward end 148 of the panel 142. Fasteners
150 of the type shown above in Figure 3 extend between
the forward end 146 of the lnner of each pair of over-
lapping paneLs 142 and the slot 144 of the outer of
each pair of overlapping panels 142. In this embodi-
ment, the fasteners 150 pass through openings in the
forward ends 146 of the panels 142, and these openings
are preferably positioned within six inches of the
extreme forward edge of the panels 142. Preferably,
the fasteners 150 are each positioned forwardly of the
adjacent blockout 160.
The panels 142 are supported above the yround
on ground supports 152 which in this embodiment take
the form of separate concrete foundations. Of course,
a single concrete slab or other suitable foundation may
be substituted in alternate embodiments. The ground
supports 152 support vertical panel supports 154, which
in this embodiment take the form of I Beams as described
above in conjunction with the first preferred embodi-
ment. Each of the panel supports 154 is secured to the
respective ground support 152 by a respective slip base
156 of the type described above in conjunction with
Figure 7. In each case, four fasteners 158 are includ-
ed in the slip base 156 to secure the ground support
152 to the panel support 154. The slip bases 156 are
arranged to resist lateral forces exerted transverse to
the longitudinal extent of the guardrail assembly 140,
while allowing the panel supports 154 to move axially,
~ ~91;3~;
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off of the ground supports 152, in response to axial
forces applied by an impacting vehicle. Generally, the
rearward slip base 156 which supports the forward end
of the beam 112 is fastened together more tightly than
the other slip bases 156 to cause it to release last.
In each case an I Beam blockout 160 is bolted
between the respective panel support 154 and the for-
ward end 146 of the respective panel 142. The block-
outs 160 space the panels 142 laterally towards the
roadway with respect to the pa~lel supports 154. The
forward most end of the guardrail assembly 140 defines
a curved nose piece 162. In this embodiment the curved
nose piece 162 is formed of a plastic which cleforms
easily to allow the impacting vehicle to engage the
forward most end of the front fender panel 142. Also,
one or more of the panel supports 154 may support a
container 164, similar to that described above in
conjunction with Figure la. These containers 164 are
preferably adapted to contain between two and three
hundred pounds of sand to increase the inertial mass of
the guardrail assembly 140.
Turning now to Figures lla-lle, these figures
illustrate one mode of operation of the barrier 100
when struck by an impacting vehicle 104. Preferably,
the slip base 156 at the forward end of the rotatable
beam 112 is tightened to a greater extent than the re-
maining slip bases 156 so that it is the last to release.
In many applications, it is preferable to provide the
two forward most slip bases 156 with flared openings to
increase the angular range of impact directions that
will cause the slip bases 156 to release.
Figure lla shows the barrier 100 in its orig-
inal position with a vehicle 104 proceeding axially
toward the pole 102. As shown in Figure llb, the first
step in the collision is for the forward most slip base
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5~:;
156 to release and the forward most panel 142a to slide
rearwardly with respect to the remaining panels 142b-142e.
As shown in Figure llc, when the forward most panel
142a moves to the rear to the maximum extent permitted
by the slot 144, the forward most panel 142a tends to
rotate away from the roadway, thereby exerting a later-
al force on the impacting vehicLe 104 which tends to
move the vehicle 104 away from the roadway. This
lateral force is a result of the "pole vaulting effect"
discussed above.
This action of the co:Llapsing guardrail assem-
bly 140 is provided by the asymrnetrical structure of
the telescoped panels 142. When the forward most panel
142a is fully telescoped, the rearward end 148 of the
forward most panel 142a overlaps to a large extent with
the second panel 142b. This overlap substantially pre-
vents the forward most panel 142a from rotating towards
the roadway. However, as explained above, the fastener
150 is secured to the extreme forward end 146 of the
second panel 142b, which is relatively weak with regard
to its ability to resist rotation of the forward most
panel 142a away from the roadway. Because of the above
described asymmetry with respect to forces required to
bend the forward most panel 142a away from the roadway
as compared with the forces re~uired to bend the for-
ward most panel 142a towards the roadway, the forward
most panel 142a tends to rotate away from the roadway
during the impact (counterclockwise as shown in Figure
llc), thereby pushing the impacting vehicle 104 away
from the roadway as well.
Of course, once the forward most panal 142a
has telescoped completely, the second panel 142b begins
to move rearwardly and leaves its slip base 156. This
process of consecutive telescoping continues as shown
in Figure lld, with each of the panels 142 exerting a
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-18-
lateral force on the impacting vehicle 104 away from
the roadway as the collapse of the guardrail assembly
140 continues.
In the event this proyressive collapse of the
guardrail assembly 140 continues to the point where the
vehicle 104 exerts significant compressive forces on
the rotatable beam 112, such compressive forces on the
beam 112 will cause the beam 1].2 to indent the spacer
128 against the pole 102, thereby releasing the slip
base 156 of the beam 112. Once the slip base 156 is
released, the beam 112 is free to rotate about the pole
102. The beam 112 is relatively rigid, and it exerts a
large lateral force on the impacting vehicle 104 as it
is rotated around the pole 102 by the vehicle 104.
This large lateral force moves the vehicle 104 farther
away from the roadway, thereby diverting the vehicle
104 around the pole 102.
It should be understood that the beam 112
will not be caused to rotate with respect to the pole
102 in many cases. As shown in Figures 12a and 12b, in
the event the vehicle 104 is positioned and oriented
such that the collapsing guardrail assembly 140 moves
the vehicle 104 sufficiently away from the roadside,
the guardrail assembly 140 will buckle, allowing the
vehicle 104 to move past the pole 102 without rotating
the beam 112.
The preferred embodiment of Figures 9-12 is
adapted for use with a cylindrlcal roadside ha~ard such
as a utility pole, lamp pole, bridge pier, or the like.
Of course, if desired a cable similar to the cable 48
of Figure 1 may be used with the embodiment of Figures
9-12. The present invention can readily be adapted for
use with other relatively narrow roadside hazards which
are not cylindrical. Figures 13-15 illustrate one such
embodiment.
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.,
1~913~S
--19-
This third preferred embodiment includes a
roadside barrier 200 adapted to protect an impactiny
vehicle from contact with a wall 202. This barrier 200
includes a beam assembly 210 which includes a riyid
beam 212 similar to that described above in conjunction
with Fiyure 9. A band 214 is provided which defines a
first pair of slots 215 and a second pair of slots 217
positioned on opposite sides of the wall 202. Fasteners
219, 221 are used to secure the band 214 to the wall
202. The fasteners 219 pass through the slots 215 and
are positioned near the forward ends of the slots 215
to allow the band 214 to move forwardly with respec~ to
the fasteners 219. Conversely, the fasteners 221 pass
through the slots 217 and are positioned near the rear-
ward end of the slots 217. Thus, the slots 215, 217
are positioned so as to retard the beam 212 from rotat-
ing towards the roadway and to facilitate rotation of
the beam 212 away from the roadway.
A brace 218 is provided which includes a beam
flange 220 that is mounted to the beam 212 by fasteners
224 and a band flange 222 that is welded to the band
214. The brace 218 operates similarly to the brace 118
described above. A spacer 228 is positioned between
the wall 202 and the band 214. The barrier 200 also
includes a guardrail assembly 240 identical to the guard-
rail assembly 140 described above.
The embodiment of Figures 13-15 operates in a
manner similar to that described above in conjunction
with Figures lla 12b. In particular, the guardrail
assembly 240 shifts the impacting vehicle 104 laterally
away from the roadway as the guardrail assembly 240
collapses. In the event the impacting vehicle 104 en-
gages the beam 212, the beam 212 is shifted rearwardly
slightly, thereby partially collapsing the spacer 228.
This releases the beam 212 from its slip base and allows
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'31~55
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the beam 212 to rotate. The fasteners 219, 221 cooper-
ate with the slots 215, 217 to prevent the beam 212
from rotating towards the roadway while allowing the
beam 212 to rotate away from the roadway. The momentum
5 of the impacting vehicle therefore causes the beam 212
to rotate as shown in Figure 15, away from the roadway.
This rotation applies large lat:eral forces to the vehi-
cle, thereby redirecting the vehicle around the wall
202.
From the foregoing, it should be apparent
that two embodiments of an improved highway barrier
have been disclosed which provide importank advantages.
The asymmetrical folding of the collapsible guardrail
assembly imposes lateral forces on the impacting vehi-
15 cle, thereby redirecting the vehicle to some extent
away from the roadway. In the event these guardrail
forces are not sufficient to cause the impacting vehi-
cle to miss the roadside hazard, the vehicle engages
the rotatable beam and the beam supplies large lateral
20 forces which redirect the vehicle away from the hazard.
Because of the manner in which the panels fold when
collapsed, they provide a relatively large buffer area
against the forward portion of the impacting vehicle,
thereby reducing maximum surface loading on the vehi-
25 cle to reduce the possibility of the guardrail spearinginto the impacting vehicle.
Of course, it should be understood that a
wide range of changes and modifications can be made to
the preferred embodiments described above. For example,
30 the number of fenders used in any particular highway
barrier can be increased or decreased as appropriate
for the particular application. As pointed out above,
various types of ground bases including continuous con-
crete pads can be used. If desired, a planar keeper
35 plate can be interposed between the moveable parts of
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~3i.3~
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the slip base to retain the fasteners in position prior
to assembly. It is therefore intended that the ~orego-
iny detailed descriptlon be regarded as illustrative
rather than limiting, and that it be understood that it
is the following claims, including all equivalents,
which are intended to define the scope of this invention.
