SHIELD I™ Redirective Protection Barrier

Redirective containment should be specified where the traffic-management or road-safety design requires an errant vehicle to be contained and redirected along a barrier rather than enter a work area or strike a hazard. A site being busy, exposed or associated with roadworks does not establish that requirement on its own.

First establish the required safety function. Then confirm that the documented speed, run length, lateral space, terminals, supporting surface and road-agency conditions can be accommodated.

Dynamic deflection describes the barriers sideways movement during impact. Working width describes the total lateral space occupied by the system during that movement. SHIELD I has a documented dynamic deflection of 2.20m and working width of 2.80m.

SHIELD I™ needs the full 2.80m working width to operate as documented. Planning around the 2.20m deflection alone understates the lateral space occupied during impact.

The current Austroads conditions specify a minimum installation length of 44m between terminals, while the tested article length is 52m. Neither figure is automatically the projects length-of-need.

Length of need is the site-specific barrier length required to shield the hazard. It depends on the hazard position, traffic approach, points of redirection and system layout. The required quantity should therefore be based on the assessed installation rather than the minimum length alone.

You can find our Austroads Safety Barrier Technical Conditions for Use PDF here: https://austroads.gov.au/__data/assets/pdf_file/0024/633480/240307-TCU-Shield-I-Safety-Barrier-System-Temporary.pdf

An accepted end treatment is required at both ends of every SHIELD I™ installation. The separate SHIELD I™ terminal units complete these end treatments and remain unfilled.

The SHIELD I™ terminal is gating and requires a traversable, hazard-free run-out area measuring 18.5m × 6m from the point of redirection. It should not be treated as a crash cushion or as part of the redirective longitudinal section.

SHIELD I™ suits temporary roadworks, lane closures and civil, infrastructure or utility projects where longitudinal separation beside live traffic requires tested redirective containment. It can separate the traffic path from a work area or roadside hazard when the documented system and site conditions can be met.

For road or lane closures, SHIELD I™ is arranged along the traffic path rather than across it as a roadblock. It is not an anti-ram device or crash cushion. A road, highway or roadside label alone does not establish suitability for the application.

The current Austroads conditions for SHIELD I™ document the following foundation pavement types:

• Concrete
• Deep-lift asphaltic concrete
• Asphaltic concrete over granular material
• Flush seal over granular material
• Unsealed compacted formation

The supporting surface must be smooth and free of snag points, kerbs or obstructions that could interfere with the system’s movement. Minimum support width and the effects of the site geometry require site-specific assessment.

The Austroads record issued 7 March 2024 lists SHIELD I as Recommended for acceptance at MASH TL1, with an accepted impact speed of 50 km/h. This recommendation is not blanket approval for every Australian road network.

Each road agency determines acceptance within its jurisdiction and may apply additional conditions. The relevant agency standards and project requirements should therefore be confirmed before SHIELD I is specified or installed.

MASH TL1 establishes the tested containment level, but it does not by itself confirm that a barrier system suits a particular site. SHIELD I™ performance must be applied within its documented system conditions, including the 50 km/h accepted impact speed, working width, dynamic deflection, connected length, terminals and clear zones.

The test level establishes the performance basis. The traffic environment, barrier layout, site conditions and road-agency requirements determine whether the complete system can be specified for the project.

The complete SHIELD I™ system consists of connected longitudinal pieces and SHIELD I™ terminals at both ends. The pieces interlock and are secured with a galvanised steel drop-in joining pin. This provides a substantially stronger mechanical connection for impact loads than the moulded-only interlocks commonly used to hold delineators or dividers in line. During a collision, the steel pin helps keep adjoining pieces engaged while allowing the controlled movement required by the redirective system.

The installation must also meet the technical requirements for connected length, terminal arrangement, working width, clear zones and site conditions. Together, these components and requirements form the documented MASH TL1 redirective barrier system. Using the correct pieces alone does not establish a compliant installation.