GB2165569A

GB2165569A - Retractable road barrier

Info

Publication number: GB2165569A
Application number: GB08422446A
Authority: GB
Inventors: Alan Dunsmore
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-09-05
Filing date: 1984-09-05
Publication date: 1986-04-16
Also published as: GB8422446D0; GB2165569B

Abstract

A road traffic barrier (11) which can be raised from and lowered into a pit is provided with a damper (21) for yieldably opposing movement of the barrier under the impact of a colliding vehicle. The damper is always below the level of the road surface. <IMAGE>

Description

SPECIFICATION Barrier structure The present invention relates to a barrier structure of the kind provided in a roadway and comprising a barrier which is movable between and is settable in either selected one of a raised position in which the barrier projects above the level of the surface of the road to obstruct travel of vehicles along the road, and in which raised position the barrier normally remains when the driving of vehicles along the road is to be deterred, and a lowered position in which the barrier does not significantly obstruct travel of vehicles along the road. In a known barrier structure of the kind described, the barrier is pivoted for movement about a horizontal axis, an hydraulic ram is provided for pivoting the barrier from its lowered position to its raised position, the ram being fully extended when the barrier reaches the raised position.For retaining the barrier in the raised position, there are provided pins which can be projected hydraulically into positions in which they obstruct return of the barrier from the raised position to the lowered position. The ram and the pins together define the raised position.

The known barrier structure is intended to deter drivers from driving vehicles over the barrier, when in the raised position. In this position, the barrier is conspicuous.

An object of the present invention is the provision of a barrier structure of the kind described which is better able than is the known barrier structure to arrest a heavy vehicle driven at speed into the barrier structure, with the intention of so damaging the barrier structure that the vehicle is able to pass the barrier structure.

According to one aspect of the invention, there is provided in a barrier structure of the kind described, a control device capable of yieldably resisting movement of the barrier through a substantial range from the raised position. By yielding and maintaining resistance to movement of the barrier, the control device enables kinetic energy of a vehicle which collides with the barrier to be dissipated during a significant period of time.

In contrast with heavy vehicle is driven at speed into the stays of the known structure when the barrier thereof is in the raised position, the stays will yield substantially instantaneously and the structure may be so destroyed by the impact that it does not prevent the vehicle travelling past the structure.

Typically, the barrier of a known structure of the kind described and the barrier of a structure in accordance with the present invention have respective surfaces which are horizontal when the barriers are in their lowered positions and are inclined to the horizontal at an angle of approximately 45" when the barriers are in their raised positions. A structure in accordance with the present invention may be so arranged that the barrier can move from the raised position into a position in which this surface is or is approximately vertical, energy being dissipated throughout this move ment.

The barrier may be arranged to be movable from the raised position in a direction away from the lowered position against the resistance provided by the control device. Additionally or alternatively, the barrier may be arranged to be movable from the raised position in a direction towards the low ered position against the resistance provided by the control device.

The control device is preferably distinct from the hydraulic ram or other means provided for raising the barrier from the lowered position to the raised position.

The stays of the known barrier structure are insufficiently effective to resist movement of the barrier from the raised position, partly because the stays protrude above the road surface and would bear the initial impact of a colliding vehicle and partly because the stays would be subjected to tension, extend upwardly from the fixed part of the structure and cannot easily be restrained against upward movement when the barrier is subject to impact by a heavy vehicle travelling at speed.

The control device of a structure in accordance with the present invention is preferably disposed below the level of the surface of the road in all positions of the barrier. The control device is then unlikely to suffer direct impact of a vehicle which collides with the structure.

Furthermore, the control device and the barrier are preferably arranged to exert forces acting in at least approximately horizontal directions on adjacent parts of the structure. The structure can be embedded in a mass of concrete in the ground and thus readily supported against horizontally directed forces.

The structure may include a fixed stop which is spaced downwardly from the level of the surface of the road and with which a lower portion of the barrier is engageable to limit movement of the barrier from the raised position in a direction away from the lowered position.

According to a further aspect of the invention, there is provided in a barrier structure of the kind described a stop which is adopted to limit movement of the barrier from the raised position. The stop is preferably engageable with a lower part of the barrier.

Examples of structures in accordance with the present invention will now be described, with reference to the accompanying drawings, wherein: Figure 1 shows a rear elevation of a barrier structure embedded in a roadway and with a barrier of the structure in a raised position, material surrounding the barrier structure being omitted; Figure 2 shows a side elevation of the structure of Figure 1; Figure 3 shows a side elevation of a modified form of the structure; and Figure 4 shows a side elevation of a further modified form of the structure.

The structure illustrated in Figures 1 and 2 comprises a frame 10 disposed in a pit defined by a mass of concrete (not shown) incorporated in a roadway. The sides of the pit are vertical and the framework is a close fit against the concrete so that concrete restrains movement of the frame.

On the frame 10 there is supported a barrier 11 which is movable relative to the frame between the raised position illustrated in Figures 1 and 2 and a lowered position in which a substantially flat surface 12 of the barrier is horizontal and substantially flush with the surface of the roadway. The surface 12 is presented by a substantially flat, metal cover plate 16 supported on a number of support plates 13 arranged in spaced-apart face-to-face relation.

The major faces of the support plates are vertical and each of these plates is approximately Lshaped, having an upper limb 14 united with the cover plate and a lower limb 15 which, in all positions of the barrier, lies below the level of the road surface. As can be seen from Figure 2, when the barrier is in the raised position, the upper limbs 14 lie mainly above the level of the road surface.

In the example illustrated in Figures 1 and 2, the barrier 11 is pivotally connected with the frame 10 by means of a pivot member 17 for movement relative to the frame about an horizontal pivot axis 18 which lies below the level of the road surface. For pivoting the barrier from the lowered position to the raised position, there are provided a number of hydraulic rams connected between the frame 10 and the lower limbs 15 of respective support plates. One of these rams is represented diagrammatically in Figure 2 by the line 19. It will be noted that the rams are disposed well below the level of the road surface.

The rams 19 may limit pivoting of the barrier 11 from the lowered position to the raised position, and thereby define the raised position. For obstructing return of the barrier to the lowered position, there may be provided pins 30 which are mounted on the frame 10 for movement in a direction parallel to the axis 18. The pins may be projected into the path of the barrier and withdrawn from that path hydraulically or may be moved in one direction by springs and driven in the opposite direction hydraulically.

The underside of the barrier 11 may bear reflectors and/or lights or be painted in bright colours to render the barrier conspicuous, when raised. The surface 12 may be adapted in a similar manner to be conspicuous.

When the barrier is in the raised position, there may extend between a free end portion of the upper limb 14 of the barrier and the frame 10 at a position near to that occupied by the free end of the upper limb 14 when the barrier is in the lowered position, a cover which serves to carry paint and/or reflectors or other means for rendering the cover conspicuous. The cover may also reduce the risk of foreign matter entering the pit by partly closing the upper end of the pit. Furthermore, the cover may limit movement of the barrier from the lowered position to the raised position, during normal use.

This latter purpose also may be served by a plurality of stays substituted for the cover. The cover may be an assembly of relatively rigid elements hinged together or may be a flexible element.

The frame 10 also supports a plate 16a which lies below the plate 16, when the barrier is in the lowered position, partly to close the upper side of the pit so that, even when the barrier is raised, foreign matter is unlikely to enter the pit. It will be understood that an accumulation of foreign matter in the pit could interfere with operation of the structure.

There is further provided a control device for providing resistance to pivoting of the barrier 11 from its raised position in a direction away from the lowered position but capable of yielding whilst maintaining such resistance. in the example illustrated in Figure 2, the control device comprises a damper 21 having first and second members which can undergo relative displacement along a rectilin- ear axis, whilst providing resistance to such displacement. The resistance may be substantially uniform throughout the stroke of the damper. In the example illustrated in Figure 2, the damper is supported by the frame 10 with its axis horizontal and perpendicular to the axis 18. One damper may be provided for each support plate 13 and, since these will be arranged in a like manner, the arrangement of only one damper and the associated support plate will be described.

The lower limb 15 of the support plate presents towards the damper 21 a convex surface 22 which preferably has the form of an involute curve. There is interposed between this surface and the damper a roller 23 which is guided by the frame 10 for movement along the axis of the damper 21.

Whilst the barrier 11 is in its lowered position and whilst the barrier is in its raised position, the damper 21 remains in its fully extended condition.

Pivotal movement of the barrier from its raised position in a direction away from its lowered position drives the roller 23 towards the damper. Movement of the roller along the axis of the damper in a direction away from the limb 15 is opposed yieldably by the damper. However, if a heavy vehicle has been driven along the roadway towards the underside of the barrier 11 to collide with the upper limb 14 of the support plate 13, the damper will yield and permit the support plate to pivot about the axis 18 until the surface 12 is vertical or approximately so. During this movement of the barrier, the kinetic energy of the vehicle will be largely dissipated so that the barrier will be effective to prevent the vehicle passing the barrier.

It will be noted that pivoting of the barrier 11 from its raised position to a position in which the surface 12 is vertical involves movement of the free end of each support plate 13 through a distance which exceeds the stroke of the damper 21 and is preferably at least twice the stoke of the damper.

Since the curved face 22 of the limb 15 and the damper engage the roller 23 at respective positions which are spaced apart horizontally, but are not substantially spaced vertically, the force transmitted to the frame 10 by the damper 21 will be substantially horizontal and the reaction exerted on the limb 15 by the roller will be substantially horizontal also. Since the force exerted on the barrier by a vehicle colliding with the barrier is likely to be approximately horizontal, the resultant force exerted by the support plate 13 on the pivot member 17 also will be approximately horizontal. The horizontal forces are transmitted by the frame 10 to the surrounding concrete which supports the frame against movement or distortion.Whilst any cover or stays connected between the upper limb of the barrier and the frame may be torn from the frame 10, reliance is not placed upon the cover or stay to resist pivoting of the barrier from the raised position. If the cover or stay 20 is omitted, the ability of the barrier to arrest a vehicle is not significantly impaired.

It will be noted that the control device 21, 23 is disposed well below the level of the road surface and is therefore unlikely to be subjected to direct impact by a vehicle colliding with the barrier structure.

The frame 10 may include a stop 24 positioned adjacent to the level of the road surface for engagment with the surface 12 of the barrier 11 when the barrier is pivoted into a vertical position. The stop 24 is adapted positively to limit pivoting of the barrier in a direction away from its lowered position.

The control device preferably provides resistance to movement of the barrier through a range of at least 25 and more preferably through a range of 45" from the raised position of the barrier.

The modified structure illustrated in Figure 3 has a frame, a barrier and a pivot member arranged and constructed in a generaly similar way to those of the structure shown in Figures 1 and 2. Such corresponding parts are indicated in Figure 3 by like reference numerals with the prefix 1, and the preceding description is deemed to apply, except for differences hereinafter mentioned.

The control device of the structure illustrated in Figure 3 is a telescopic damper comprising a cylinder pivotally connected at one of its ends wtih the frame 110 and comprising a piston rod carrying a roller 127 against which the limb 115 of a corresponding support plate 113 bears when the barrier is in its raised position.

When the barrier 111 is in the raised position illustrated in Figure 3, the axis of the damper 125 is inclined to the horizontal at a small angle, for example an angle within the range 0 to 10 . As the barrier pivots from this position to a position in which the surface 112 of the barrier is vertical, the centre of the roller 127 passes through an intermediate position vertically below the pivot axis 118. In this intermediate position, the axis of the damper 125 may be horizontal. The arc through which the roller 127 moves has a substantially horizontal chord so that any force transmitted by the damper to the frame 110 acts in a substantially horizontal direction on the frame. Similarly, the reaction exerted on the arm 115 acts in a substantially horizontal direction.

The structure of Figure 3 further comprises a stop 126 which is fixed to the lowest part of the frame 110 and is spaced well below the level of the road surface. As the surface 112 of the barrier moves into a vertical position, the lower limb 115 of the support plate 113 engages the stop 126 which positively limits pivoting of the barrier.

The stop 126 also serves as a support for the damper 125 when the barrier 111 is pivoted to its lowered position. The damper then rests with its axis horizontal on the stop 126.

In the modified structure illustrated in Figure 4, certain parts also correspond to parts of the structure described with reference to Figures 1 and 2. In Figure 4, such corresponding parts are indicated by like reference numerals with the prefix 2 and the preceding description is deemed to apply, except for differences hereinafter mentioned.

The barrier 211 of the structure shown in Figure 4 is pivoted through an angle of approximately 120" from its lowered position to the raised position illustrated by an electric motor 227 having suitable transmission means for transmitting torque to the support plates 213. It is intended that the surface 212 of the barrier which faces upwardly when the barrier is in the lowered position, should be presented towards oncoming traffic when the barrier is in its raised position.

The structure of Figure 4 further comprises a control device for yieldably opposing movement of the barrier 211 from the raised position illustrated in Figure 4 towards the lowered position. This control device is in the form of a hydraulic or pneumatic damper having a cylinder 228 pivotally mounted on the frame 210 and having a piston rod 229 carrying at its free end a roller 230 for engagement with the lower limb 215 of the support plate 213.

The damper can be pivoted upwardly and downwardly relative to the frame 210 by an hydraulic lifting device 231 between the active position shown in Figure 4, in which the damper is contracted by pivoting of the barrier 211 from its raised position towards its lowered position, and an inactive position (not illustrated) in which the damper lies out of the path of travel of the lower limb 215 during pivoting of the barrier. If, when the barrier has been pivoted from the lowered position to the raised position, resistance to return of the barrier is required, the damper 228, 229 is raised into engagement with the lower limb 215 of the barrier and is held in such engagement.

The arrangement is preferably such that the roller moves, during pivoting of the barrier against the resistance provided by the damper, through an arc having a chord which is horizontal or approximately horizontal. With this arrangement, the force transmitted to the frame 210 by the damper acts in an at least approximately horizontal direction.

Alternatively the yieldable structure may be substituted by a fixed stop. In cases where a fixed stop is provided for the barrier, the yieldable structure may be omitted.

The features disclosed in the foregoing description, the following claims or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. In a roadway a structure comprising a barrier movable between and settable in either selected one of a raised position in which the barrier projects above the level of a surface of the road to obstruct travel of vehicles along the road and in which the barrier normally remains when the driving of vehicles along the road past the barrier is to be deterred, and a lowered position in which the barrier does not significantly obstruct travel of vehicles along the road, wherein there is provided a control device capable of yieldably resisting movement of the barrier through a substantial range from the raised position.

2. A structure according to Claim 1 wherein the control device is disposed below the level of the surface of the road in all positions of the barrier.

3. A structure according to either preceding claim wherein the barrier is mounted on a mounting member which lies below the level of the surface of the road in all positions of the barrier.

4. A structure according to any preceding claim wherein the barrier includes a lower portion which is, in all positions of the barrier, below the level of the surface of the road, and wherein the control device co-operates with the lower portion of the barrier.

5. A structure according to Claim 4 wherein there is further provided a raising device which cooperates with the lower portion of the barrier to move the barrier from the lowered position to the raised position.

6. A structure according to Claim 4 or Claim 5 further comprising a fixed stop spaced downwardly from the level of the surface of the road and with which the lower portion of the barrier is engageable to limit movement of the barrier from the raised position in a direction away from the lowered position.

7. A structure according to any preceding claim wherein the control device comprises first and second components which, when the barrier moves from its raided position against resistance provided by the control devices undergo relative displacement along an axis which is nearer to the horizontal than to the vertical.

8. A structure according to any preceding claim wherein the barrier is arranged for pivoting about a horizontal pivot axis, the barrier has a free margin which is the uppermost part of the barrier when the barrier is in the raised position and the control device acts on the barrier at a position which is substantially nearer to the pivot axis than is said free margin.

9. A structure according to any preceding claim wherein the control device is arranged to provide resistance to angular movement of the barrier through a range of at least 25".

10. A structure substantially as hereinbefore described with reference to and as shown in Figures 1 and 2 of the accompanying drawings or modified substantially as herein described with reference to and as shown in Figure 3 or Figure 4 of the accompanying drawings.

11. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.