AU2006100679A4 - Improved permanent road barrier system - Google Patents

Description

P01l Section 29 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990 00 C0 COMPLETE SPECIFICATION INNOVATION PATENT Application Number: Lodged: Invention Title: Improved permanent road barrier system The following statement is a full description of this invention, including the best method of performing it known to us:

INO

O A PERMANENTLY INSTALLED NINTERLOCKING CRASH BARRIER SYSTEM FIELD OF THE INVENTION 00 The present invention relates generally to a crash barrier system for use in 0 proximity to traffic, upon roads and bridges, and it will be convenient to hereinafter describe the invention in relation to these applications. It should be appreciated, however, that the present invention is not limited to those Oapplications only, and may also find use in other areas such as, for example, Smotor sport racing tracks and the like.

BACKGROUND OF THE INVENTION A variety of crash barrier systems have been used at the sides of roads, as median strip barriers on highways and freeways, and parapets at the sides of bridges. Such crash barrier installations function to prevent vehicles from leaving the roadway, for example, at the edge of a cliff or the edge of a bridge and also function to prevent vehicles of which the driver has lost control moving into oncoming traffic by providing a median strip barrier dividing a highway or road. A wide variety of installations have been carried out and historically, for example, bluestone block bridges having parapets of individual bluestone blocks are one method of providing a crash barrier. Other forms of barrier have been created from various materials, such as concrete.

Poured concrete barriers provide flexibility in design and reduced labour costs when compared to bluestone blocks and the like. The heavy concrete barriers may be secured to the ground, or bridge deck, in a variety of ways, to provide a permanent installation in which the impact load of a vehicle is resisted both by the mass of the concrete barrier and by the barrier being secured to the ground.

One form of crash barrier for installation on the sides of roads, which has been developed in order to standardise installations, and to reduce labour and installation costs, consists of precast concrete blocks, which are bolted or otherwise attached to concrete footings or foundations. Concrete foundations or footings, as well as the concrete blocks themselves, may be provided in a variety of configurations. Each concrete block is aligned with other blocks in a series and O is fixed to a support surface. This support surface may be a concrete foundation, C the deck or side of a bridge, or some other surface such as a road-bed in some ;Z median strips. The block may be anchored or bolted to the concrete footings or foundations and examples of such arrangements may be seen in Figures la, 3 00 S 5 and 4 of the drawings attached hereto.

Such barriers are of great value in relatively minor impact collisions, generally preventing, for example, a passenger car from leaving a roadway, or afrom plunging from a bridge. Where high impact loads are applied as may occur when a large truck or semitrailer hits such a barrier, it is common for these C 10 precast blocks to detach from the support surface due to the impact, and, as is Sshown in Figures 1 b and 1 c, for the block to move out of alignment with adjacent blocks in the series and indeed into what may be oncoming traffic, or in the case of a bridge over railway, for the barrier block to fall onto rail tracks.

In such a situation, the dislodgment of a concrete block has extremely serious consequences and may result in the cause of further accidents and injury to previously uninvolved parties. In an attempt to strengthen the connection between adjacent blocks in a series, the use of a shear key has been attempted.

A rebate on each end of the blocks in the series is, after the blocks are installed and aligned in position, filled with concrete or grout in order to provide a shear key that prevents lateral movement (or shearing) between blocks. Unfortunately, in practice, it has been found that the shear key is ineffective in preventing the relative movement of blocks when an impact load of sufficient force to dislodge a block from its support surface is applied. Typically, the shear key shatters and has no real effect.

It is therefore desirable to provide a system in which the use of precast concrete blocks may be continued, with minimised adverse impact upon labour or installation costs, and yet in which occurrence of catastrophic failure of the barrier system is reduced even when large impact loads are applied.

SUMMARY OF THE INVENTION A first aspect of the present invention provides a permanently installed interlocking crash barrier system including: a plurality of barrier blocks; and

IND

O interlocking means for interlocking a series of said blocks adjacent Cl to one another; and securing means for securing the base of said blocks to a support surface such that each block is secured as a permanent installation; 00 0 5 whereby, upon an impact load being applied to one or more of said blocks, the load is distributed to one or more adjacent blocks in the series via tensioning r- of said interlocking means; and whereby, upon any failure of said securing means due to said impact load, said interlocking means allows relative lateral movement between adjacent blocks 0 10 while restraining said blocks in substantially interlocked configuration.

Cl Preferably, said interlocking means includes a first hook extending from each of said blocks in the series towards a respective adjacent block in the series, and a second hook extending from said respective adjacent block, said first and second hooks adapted to interlock.

Preferably, each of said first hooks is a vertically aligned plate formed into a or cross-section adapted to interlock with a respective second hook, also being a vertically aligned plate formed into a or cross-section.

A second aspect of the present invention provides a method of permanently installing an interlocking crash barrier system according to the first aspect of the invention, including: locating said plurality of barrier blocks in interlocking relationships; and securing said plurality of blocks such that the base of each block is permanently secured to the support surface.

Advantageously, by installing the barrier blocks in an interlocking relationship in which an impact load is distributed to adjacent blocks by tensioning of the interlocking means, a higher impact load can be applied before the securing means to the support surface fails. For example, where each of the series of barrier blocks are secured to a concrete footing or foundation via steel bolts, an impact load upon one block in the series will be distributed by the interlocking means in tension, and the load carried in part by the securing bolts of adjacent blocks.

INO

O Tensile connection of blocks in a series is far more effective in preventing Ssignificant displacement of a block than mere mechanical restraint of lateral ;Z movement, such as a shear key, as allowing limited tensile play both distributes load, and reduces the likelihood of failure of the interlocking means.

00 S 5 The distribution of the load via tensile interlocking means, such as interlocking steel hooks, also allows for load to be dissipated further by the deformation of the hooks, whilst still remaining in an interlocking relationship.

OThis contrasts with prior art where a shear key merely shatters without absorbing significant load. Furthermore, because the load is distributed to adjacent blocks 0 10 via the interlocking means, it is less likely that the securing means of a given N block, to its concrete foundation or other support, will fail. Where the securing the means does fail, the block is substantially restrained from lateral movement by the interlocking to adjacent blocks in tension. The likelihood of a block being displaced such that it enters oncoming traffic, or falls from a bridge, is significantly reduced.

The advantage of a preferred embodiment of the invention having vertically aligned plates formed into or hooks is that barrier blocks may be lifted vertically and aligned in correct position, whilst being significantly laterally restrained both during installation and once permanently installed. It is not necessary to otherwise connect the blocks together the operation is very similar to existing installation methods for permanent concrete crash barriers and therefore there is minimal increase in labour and installation costs.

While concrete crash barrier blocks are a popular choice, the invention may also be employed with blocks made from other suitable materials.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of one or more preferred embodiments of the proven invention will be readily apparent to one of ordinary skill in the art from the following written description with reference to and, used in conjunction with, the accompanying drawings, in which: Figures la to 1c are perspective drawings of a prior art crash barrier system; and Figure 2 is a plan view of a prior art shear key; and

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O Figure 3 is a cross sectional side view of a prior art crash barrier installed C adjacent a roadway; and Figure 4 is a cross sectional side view of a prior art crash barrier or parapet installed upon a bridge deck; and 00 0 5 Figure 5a is a cross sectional view of a prior art median strip crash barrier; and Figure 5b is an end view of a prior art median strip crash barrier having a Sshear key rebate; and Figure 6 is a side elevational view of adjacent crash barrier blocks 0 10 according to a preferred embodiment of the present invention; and N Figure 7 is a top view of adjacent crash barrier blocks according to the embodiment of Figure 6; and Figure 8 is a perspective view of adjacent crash barrier blocks according to the embodiment of Figures 6 and 7.

DESCRIPTION OF PREFERRED EMBODIMENT Figure la shows a series of prior art crash barrier blocks 10 aligned in a series, each block being secured to a supporting surface 20 (being a concrete footing or foundation) by steel bolts 22. Rebates 12 in each end of each block in the series are aligned, and filled with concrete or grout to create a shear key 14 that restrains the blocks from relative lateral movement. Unfortunately, as has been discussed above and as is shown in Figures 1 b and 1c, upon a high impact load being applied to one or more of the blocks 10, the shear key 14 shatters and the securing bolts 22 may also fail catastrophically, thereby allowing relative lateral movement of each of the blocks 10. This may displace blocks, or even, as is shown in Figure 1c, cause blocks to be dislocated a significant distance into oncoming traffic, or over the edge of a bridge.

Figure 2 shows a plan view of two prior art adjacent blocks 10 with aligned rebates 12 into which concrete has been poured to form a shear key 14.

Figure 3 shows a cross sectional view of an alternative prior art crash barrier block 30 in which steel reinforcing 44 is used as a securing means to secure the block 30 to the support surface or footings 40. Additional steel

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O reinforcings 42 are laid horizontally to assist in securing the crash barrier block C 30, and further reinforcing means 46 may also be provided.

;Z Despite the additional securing means provided in the prior art design of Figure 3, catastrophic failure of the steel reinforcing can still occur, and the 00 S 5 connection of adjacent blocks 30 by use of a shear key is ineffective in restraining the blocks 30 from relative lateral movement.

Figure 3 also shows two service conduits 48 through which electrical, Slighting or other service connections may be passed as necessary. Each block in a series is aligned such that the service conduits 48 also align.

0 10 Figure 4 shows a cross sectional view of a crash barrier block 50 according N to another prior art design, adapted to be secured as a parapet on a bridge. The concrete block 50 is reinforced by steel bars 62 and secured to the bridge deck 67 by the interconnection of steel bars 64 (protruding from block 50) and bars 66 (protruding from bridge deck 67). Horizontal steel bars 65 interconnect steel bars 64 and 66. This securing means is further secured and protected by concrete curbing 60, which is poured over the assembly.

Another prior art arrangement of a reinforced concrete crash barrier block is shown in cross section in Figure 5a, and in end view in Figure 5b. The block is reinforced by steel bars 72 and has a rebate 74 in each end. Each block maybe secured to concrete footings (not shown) by bolts or other means (not shown). A block of this configuration is suitable for use in an application such as a median divider.

The prior art installation of such crash barrier blocks, is, as previously described, inadequate when a high impact load is supplied to one or more of a series of such blocks. As the blocks are secured only to a support surface such as concrete footings, a high impact load results in a block being displaced from the series, even into oncoming traffic. Where a load is applied towards the top of a crash barrier block, in addition to the lateral force, a bending moment is also created and failure of the securing means to the support surface becomes even more likely. The previously mentioned attempts to prevent lateral movement of blocks by providing a shear key arrangement between the blocks in the series is ineffective in preventing displacement of blocks. Accordingly, an alternative

IND

O means of preventing or reducing the occurrence of substantial displacement of N blocks is indicated.

Figure 6 shows a side view of a preferred embodiment of the present invention. Two adjacent crash barrier blocks 100 each have vertically aligned 00 0 5 plates 110 which are formed into a configuration as shown in the plan view of Figure 7. These plates, hereinafter referred to as hooks 110 are adapted to r- engage each other in tension. Each block 100 is positioned through vertical movement relative to an adjacent block 100 as shown in the perspective view of Figure 8.

IND

0 10 In the preferred embodiment of the invention shown in Figures 6 to 8, the hook 110 at one end of the block 100 is recessed in a rebate 112 and receives the protruding hook 110 of an adjacent block 100 as the adjacent block 100 is lowered vertically into alignment in the series. Substantial lateral movement of the blocks relative to each other is prevented firstly by the protruding hook 110 residing within the rebate 112 of the adjacent block 100 in the series, and secondly due to the interlocking in tension of the adjacent hooks 110. When an impact load is applied to one block 100 in the series of such interlocked blocks 100, the hooks 110 engage and interlock in tension, thereby preventing substantial lateral movement or dislocation of a given block 100.

Installation of blocks 100, according to the preferred embodiment of the invention, involves vertically aligning and lowering into interlocked relation each block in the series, onto the support surface. The interlocked hooks 110 may have some play available between them, as this increases ease of installation.

However, upon application of an impact load, this play is quickly taken up so that the hooks are interlocked in a tension relationship.

The support surface may be a previously prepared concrete footing or foundation, a bridge deck or other known support. The embodiment shown in Figure 8 is suitable for installation onto a bridge deck and has steel bars 114 protruding from block 100, for interconnection with securing means on a bridge deck (not shown).

Preferred embodiments of the invention may have securing means to be positioned into a 'wet' foundation or may be attached, eg by bolting, to a dried

IND

O foundation. Known techniques of securing blocks to a support surface/foundation C may be used.

An impact load applied to one block 100 in a series will be transferred via tension through the interlocked hooks 110 to adjacent blocks 100 in the series.

00 0 5 This transfer of load to adjacent blocks 100 in the series results in smaller loads being applied to the securing means (not shown in Figures 6 to 8) of each of the r- crash barrier blocks 100 that secure the blocks 100 to a supporting surface, such Sas a concrete foundation or bridge deck. Because an impact load is carried not by one block and its securing means, but rather by two, three, five or more blocks 0 10 and their securing means, the load is dissipated and failure of the securing means N is less likely. Where failure of the securing means does result, a block 100 that is no longer secured to its supporting foundations is still generally laterally restrained due to the interlocking of the hooks 110 of that block 100 with the 'J' hooks 110 of adjacent blocks 100. Although some relative movement, including lateral movement, between adjacent blocks may occur, the interlocking means or hooks act to prevent major dislocation of a block (eg into oncoming traffic) because the block remains interlocked in a series, the end points of which are likely to have securing means that have not failed.

As the interlocking means or hooks 110 operate under tension, they are unlikely to shatter under application of a shearing force or load. Even if the securing means fails, the interlock means acts to laterally restrain the blocks 100.

Accordingly, catastrophic failure and significant displacement of a block 100 in a series is unlikely. Where the load is of such magnitude that the interlocking means or hooks 110 themselves begin to fail, impact energy is further dissipated through deformation of the hooks 110, which are preferably steel.

By locating the hooks 110 at or near the top of the series of concrete blocks 100, not only are the adverse results of an impact from a lateral impact load reduced, but also the adverse results of an impact load applied at or near the top of a concrete block 100, as the bending moment created is also transferred to adjacent blocks 100 in the series. Another advantage of locating the hooks 110 near the top of a concrete block 100 is that service conduits 130 may pass through concrete blocks 100 without interruption. This is not the case where

IND

O attempts to strengthen a shear key are made, by extending the length of the C shear key to the full height of a block.

;Z As the present invention maybe embodied in several forms without departing from the spirit of the central characteristics of the invention, it should be 00 S 5 understood that the above described embodiment is not to limit the present invention unless otherwise specified, but rather should be construed broadly r- within the spirit and scope of the present invention as defined in the appended aclaims. Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the present invention and appended 0 10 claims. For example, the vertical plates or hooks maybe replaced by other N hook arrangements including hooks, or indeed other interlocking arrangements with similar functionality. While it is desirable that blocks may be positioned in series by simple vertical placement, ring bolts, loops and other arrangements are also encompassed as means for interlocking adjacent blocks to each other.

Reinforcing bars connecting the two hooks of a given block may be desirable in some applications, in order to increase the tensile strength between adjacent blocks in a series. The term 'concrete block' has been used herein, but is not intended to preclude other materials from which crash barrier blocks may be manufactured.

Claims (3)

1. 2. A permanently installed interlocking crash barrier system according to claim 1, wherein said interlocking means includes a first hook extending from each of said blocks in the series towards a respective adjacent block in the series, and a second hook extending from said respective adjacent block, said first and second hooks adapted to interlock.
2. 3. A permanently installed interlocking crash barrier system according to claim 2 wherein each of said first hooks is a vertically aligned plate formed into a or cross-section adapted to interlock with a respective second hook, also being a vertically aligned plate formed into a J' or cross-section.
3. 4. A permanently installed interlocking crash barrier system substantially as hereinbefore described, with reference to any one of the embodiments shown in the accompanying Figures 6 to 8. A method of permanently installing an interlocking crash barrier system according to any one of the proceeding claims including: locating said plurality of barrier blocks in interlocking relationships; and NO O- securing said plurality of blocks such that the base of each block is c permanently secured to the support surface. DATED this 8 t h day of August 2006 00 AUSTRALIAN ROAD BARRIERS PTY LTD a\ SWATERMARK PATENT TRADE MARK ATTORNEYS S290 BURWOOD ROAD HAWTHORN VICTORIA 3122 0 AUSTRALIA MCQ/BJW/LMK