Twist box guardrail terminal

Abstract

This guardrail terminal design incorporates an impact head of open front configuration adapted with the rear portion as a funnel disposed with the narrow end of the funnel facing forward which will flatten the W beam guardrail as it moves down the beam when impacted by a vehicle. Tension is maintained on the beam by flat strips connected from the beam through top open front of the impact head and is attached to a front anchor post. A wedge shaped reverse direction bracket with slotted bolt holes such that the slots open toward the traffic direction disposed at the back of the impact head where it connects to the guardrail will allow for reverse direction impacts to be accounted for.

Claims

1. A twist box guardrail terminal comprising: a guardrail formed as a beam; an impact head of open front configuration receiving the guardrail therethrough, and adapted to flatten the beam as the impact head moves down the beam when impacted by a vehicle from an oncoming traffic direction; a wedge shaped reverse direction bracket attached to the impact head and attached to the beam, the reverse direction bracket comprising a first portion fixedly attached to the impact head, a second portion attached to the beam, and an angled portion connecting the first and second portions at rear ends thereof opposite to the oncoming traffic direction, and defining a wider part of the wedge shape at the end of the bracket facing oncoming traffic, wherein the second portion includes slotted bolt holes having slot openings at a forward end thereof open to the oncoming traffic direction, and the reverse direction bracket is attached to the beam with bolts mounted through the slotted bolt holes; a front anchor embedded in the ground; and a connector member attached to a forward end of the guardrail facing the oncoming traffic direction, the connector member extending from the guardrail through the open front of the impact head and being attached to the front anchor, wherein the reverse direction bracket provides an initial braking force by being configured such that the bolts slide out of the slotted bolt holes upon an impact to the impact head by a vehicle from the oncoming traffic direction, and wherein upon impact from a vehicle to the impact head, movement of the bolts within the slotted bolt holes enables the impact head to be pushed in a direction parallel to oncoming traffic such that the beam is pulled through the open front of the impact head.

2. A twist box guardrail terminal as set forth in claim 1, wherein the impact head includes a funnel-shaped rear portion disposed with the narrow end of the funnel facing forward.

3. A twist box guardrail terminal as set forth in claim 1, wherein the impact head includes a rear portion in the shape of a partial funnel, straight at the top and bottom but sloped along the sides, with the narrow end of the partial funnel facing forward.

4. A twist box guardrail terminal as set forth in claim 1, wherein the connector member is a flat strip attached to the guardrail such that the flat strip extends from the guardrail through the open front of the impact head and are attached to the front anchor.

5. A twist box guardrail terminal as set forth in claim 1, wherein the connector member is a plurality of flat strips attached to the guardrail such that the plurality of flat strips extend from the guardrail through the open front of the impact head and are attached to the front anchor.

6. A twist box guardrail terminal as set forth in claim 1, wherein the connector member is a plurality of flat strips attached to the guardrail such that the plurality of flat strips extend from the guardrail through the open front of the impact head, are turned 90 degrees relative to the plane of the beam, and are attached to the front anchor post.

7. A twist box guardrail terminal as set forth in claim 1, wherein the connector member is a plurality of wire strips attached to the guardrail such that the plurality of wire strips extend from the guardrail through the open front of the impact head and are attached to the front anchor.

8. A twist box guardrail terminal as set forth in claim 1, wherein the connector member is a plurality of cables attached to the guardrail such that the plurality of cables extend from the guardrail through the open front of the impact head and are attached to the front anchor.

9. A twist box guardrail terminal as set forth in claim 1 further comprising: the front anchor being a post embedded in the ground.

10. A twist box guardrail terminal as set forth in claim 1 further comprising: the front anchor being embedded in the ground adapted with a connector plate portion of it above ground.

11. A twist box guardrail terminal as set forth in claim 1 further comprising: the front anchor being embedded in the ground adapted with a connector plate portion of it below ground.

12. A twist box guardrail terminal comprising: a guardrail formed as a W beam; an impact head of open front configuration receiving the guardrail therethrough, and adapted to flatten the beam as the impact head moves down the beam when impacted by a vehicle from an oncoming traffic direction, the impact head including a funnel-shaped rear portion disposed with a narrow end of the funnel facing forward toward the oncoming traffic direction; a wedge shaped reverse direction bracket comprising a first portion fixedly attached to the back of the impact head, a second portion attached to the guardrail, and an angled portion connecting the first and second portions at rear ends thereof opposite to the oncoming traffic direction, and defining a wider part of the wedge shape at the end of the bracket facing oncoming traffic, wherein the second portion includes slotted bolt holes having slot openings at a forward end thereof open to the oncoming traffic direction; bolts attaching the reverse direction bracket to the guardrail through the slotted bolt holes in the reverse direction bracket; bolts attaching the impact head to the reverse direction bracket; a plurality of flat strips; a front anchor post embedded in the ground and including a connector plate portion; bolts attaching the flat strips to a forward end of the guardrail facing the oncoming traffic direction such that each of the flat strips are twisted ninety degrees relative to the plane of the guardrail and extends through the open front of the impact head; and bolts attaching the flat strips to the front anchor post, wherein the reverse direction bracket provides an initial braking force by being configured such that bolts slide out of the slotted bolt holes upon an impact to the impact head by a vehicle from the oncoming traffic direction, and wherein upon impact from a vehicle to the impact head, movement of the bolts within the slotted bolt holes enables the impact head to be pushed in a direction parallel to oncoming traffic such that the beam is pulled through the open front of the impact head.

13. A twist box guardrail terminal comprising: a guardrail formed as a W beam; an impact head of open front configuration receiving the guardrail therethrough, and adapted to flatten the beam as the impact head moves down the beam when impacted by a vehicle from an oncoming traffic direction, the impact head including a rear portion in the shape of a partial funnel such that the top and bottom are straight but the sides narrow, with a narrow end of the funnel facing forward toward the oncoming traffic direction; a wedge shaped reverse direction bracket comprising a first portion fixedly attached to the back of the impact head, a second portion attached to the guardrail, and an angled portion connecting the first and second portions at rear ends thereof opposite to the oncoming traffic direction, and defining a wider part of the wedge shape at the end of the bracket facing oncoming traffic, wherein the second portion includes slotted bolt holes having slot openings at a forward end thereof open to the oncoming traffic direction; bolts attaching the reverse direction bracket to the guardrail through the slotted bolt holes in the reverse direction bracket; bolts attaching the impact head to the reverse direction bracket; a plurality of flat strips; a front anchor post embedded in the ground including a connector plate portion; bolts attaching the flat strips to a forward end of the guardrail facing the oncoming traffic direction; and bolts attaching the flat strips to the front anchor post such that each of the flat strips is twisted ninety degrees relative to the plane of the guardrail and extends through the open front of the impact head before being attached to the front anchor post, wherein the reverse direction bracket provides an initial braking force by being configured such that bolts slide out of the slotted bolt holes upon an impact to the impact head by a vehicle from the oncoming traffic direction, and wherein upon impact from a vehicle to the impact head, movement of the bolts within the slotted bolt holes enables the impact head to be pushed in a direction parallel to oncoming traffic such that the beam is pulled through the open front of the impact head.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a side view of the guardrail end, the last two support posts adapted to safely shear away and the post mounted in the ground in front of the impact head with the flat strips anchored to it.

(2) FIG. 2 is a top view of the guardrail end, the last two support posts adapted to safely shear away and the post mounted in the ground in front of the impact head with the flat strips anchored to it.

(3) FIG. 3 shows the reverse direction bracket.

(4) FIG. 4 shows the fastening of the flat straps to a W beam.

(5) FIG. 5 shows the bottom view of the end terminal with the interior throat which compresses the W beam and guides it to remain within the terminal.

THE PREFERRED EMBODIMENT

(6) Guardrail 1, formed as a W (cross section) beam, is supported by a plurality of support posts 2. Impact head 3 is attached to the guardrail 1 by bolts, screws, rivets, nails, glue or welding. In the preferred embodiment, bolts 10 are the means to attach impact head 3. Reverse direction bracket 4 connecting impact head 3 to guardrail 1 is adapted with slotted bolt holes such that the slots open forward (toward the oncoming traffic). Reverse direction bracket 4 is attached to impact head 3 by means of attachment such as bolts, screws, or rivets. In the preferred embodiment bolts 11 are the means of attachment. Reverse direction bracket 4 is then attached to guardrail 1 by bolts 12 through the slotted bolt holds. Any slidably attached method would work such as bolts, rivets, nails, or screws as long as the method fits into the slots and as long as it allows for the reverse direction bracket to slide relatively easily when hit in the direction of oncoming traffic (forward). Near reverse direction bracket 4, impact head 3 is attached to guardrail 1 by any suitable means such as welding, screws, bolts, nails or glue. In the preferred embodiment, bolts 13 are the attachment means.

(7) Reverse direction bracket 4 is adapted to be wedge shaped and attached with the wider part of the wedge shape at the forward end in order to channel the bumper or fender of a vehicle colliding with the guardrail from the opposite direction of the usual direction of travel. Impact head 3 is adapted to flatten the W beam guardrail 1 as it moves down the guardrail when impacted by a object in the front. This is accomplished by having the inside of rear portion 15 shaped like a funnel with the narrow end facing the oncoming traffic direction (forward) as shown in FIG. 5.

(8) At least one, but preferably a plurality, of flat strips 5, made of high toughness and tensile strength material, are attached to guardrail 1. FIG. 4 shows the strips attached to the W beam with bolts. Wire rope, cable, or other similar means of providing tension will suffice to create tension but will not twist the guardrail as it is moved under impact. Best results in protecting the occupants are obtained by flattening and twisting the guardrail ninety degrees so it is roughly parallel to the road. Front anchor post 6 is embedded in the ground with only the connector plate portion of it above ground or under ground near the surface. Each of the flat strips 5 that are attached to guardrail 1 extend through the front of impact head 3, are twisted ninety degrees relative to the plane of guardrail 1, and are attached to front anchor post 6. Any means of attachment is sufficient such as welding, rivets, bolts, screws, nails or glue. The preferred embodiment attaches flat strips 5 to front post 6 with bolts 14.

(9) First support post 7 is placed behind impact head 3 embedded into the ground and attached to guard rail 1.