Safety on Victoria's Roads—Regional Road Barriers

Tabled: 18 June 2020

Appendix C. Technical details of road safety barriers

Roadside and median barriers

Road safety barriers can be installed on the side or middle sections of roads to prevent different types of crashes.

Figure C1
Roadside and median barriers

Figure C1  Roadside and median barriers

Source: VAGO, based on information from VicRoads.

Semi-rigid and rigid barriers

VicRoads installs different types of safety barriers depending on the road and ground conditions. VicRoads classifies road safety barriers as flexible, semi rigid or rigid. Guard fence and concrete barriers are examples of semi-rigid and rigid barriers.

Flexible barriers

How do flexible barriers work?

Flexible barriers are designed to flex when they are hit. This is known as dynamic deflection. As shown in Figure C2, the dynamic deflection and working width determines how far the barrier needs to be installed from the hazard.

Figure C2
Dynamic deflection and working width

Dynamic deflection is the lateral displacement or ‘give’ of a flexible barrier when it is struck.

Working width is the minimum width required to prevent an impacting vehicle from colliding with an object behind a flexible barrier.

Figure C2 Dynamic deflection and working width

Source: VAGO.

The dynamic deflection and working width for flexible barriers vary. Road managers must allow a minimum working width for the barrier to deflect and stop a vehicle from hitting the hazard behind it. If there is less space for a barrier to flex, then the deflection decreases and the potential for injuries to vehicle occupants increases.

Wire rope and steel system barriers

Wire rope and steel system barriers are two examples of flexible barriers that VicRoads has installed under the Top 20 Program.

Both types of barriers prevent run-off-road crashes by redirecting colliding vehicles. However, wire rope barriers need more space to flex compared to steel system barriers. Road managers need to consider this when installing barriers in locations where the road is close to a cliff edge or there is a steep drop-off close to the road.

Figure C3 outlines the key differences between wire rope barriers and steel systems.

Figure C3
Characteristics of wire rope barriers and steel systems

Figure C3 Characteristics of wire rope barriers and steel systems

Source: VAGO, based on information from VicRoads.

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