Road Safety Barriers FAQs
What is a road safety barrier?
A road safety barrier, also known as a guardrail barrier, crash barrier or traffic barrier is a system designed to prevent errant vehicles from departing the safe travelled way and colliding with a roadside hazard or oncoming vehicle.
What is the difference between a permanent safety barrier and temporary safety barrier?
A permanent safety barrier is designed for long-term installation and cannot be relocated. A temporary safety barrier, also known as a workzone barrier, is typically used at construction sites. Temporary barriers are often freestanding allowing them to be relocated throughout the worksite.
How are road safety barriers evaluated?
Road safety barriers are full-scale crash tested to assess compliance with Australian and International Standards. The Manual for Assessing Safety Hardware (MASH) is the basis of crash testing nominated by AS/NZS 3845.1 and is the recommended crash test standard nominated by the Austroads Safety Barrier Assessment Panel (ASBAP). MASH provides guidelines for the barrier configuration, vehicle type, vehicle speed and impact angle.
What is the crash test evaluation criteria for a road safety barrier?
The outcome of a road safety barrier crash test considers the structural adequacy of the barrier, the stability of the impacting vehicle and occupant risk.
How do I select the most appropriate road safety barrier for my project?
To select the most appropriate road safety barrier for your project, the Austroads Guide to Road Design Part 6: Roadside Design, Safety and Barriers (AGRD06-22) provides a structured, risk-based and context-sensitive process. The Guide provides a barrier design process which includes collection of site information, defining the hazard, determining the position of the barrier, assessing barrier deflection and working width, and determining the barrier containment level.
What is the dynamic deflection of a road safety barrier?
Dynamic deflection is the maximum lateral movement of a road safety barrier system when struck by a vehicle during crash testing. It represents how far the barrier deflects or bends under impact, measured from its original position to the furthest point displaced during collision.
What is the working width of a road safety barrier?
Working width is the maximum distance from the traffic-side face of a road safety barrier to the farthest point reached by any part of the system or vehicle during impact. It includes both the barrier’s dynamic deflection and the vehicle roll or sway allowance, ensuring the barrier and vehicle remain clear of the hazard being shielded.
How do I evaluate a roadside hazard?
Roadside hazards are evaluated by identifying the hazard type and offset, assessing exposure, likelihood, and severity, calculating a risk score, comparing it to the NRRIT, and selecting appropriate mitigation or barrier treatment.
What is the NRRIT?
The NRRIT (Network Roadside Risk Intervention Threshold) is the risk score value that defines when a safety barrier is required. The NRRIT varies by road type, environment, and speed, and is typically determined by each Australian road agency based on Austroads’ risk charts.
How do I determine if a road safety barrier is approved for use?
Each Australian state road agency publishes a list of approved road safety barrier systems. Each safety barrier system should be installed as per product specific Technical Conditions for Use.
Road Safety Barriers Products
Guardrail Barriers are steel, longitudinal barrier systems designed to contain and redirect errant vehicles away from roadside hazards. Guardrail barriers feature steel posts supporting w-beam or thrie-beam guardrail.
Guardrail Terminals are installed at the ends of the longitudinal guardrail safety barrier system to mitigate the risk of impacts at the end of the system and to anchor the system facilitating safe vehicle containment and redirection.
Motorcycle protection rail or rub-rail is positioned underneath and parallel to the guardrail beam, shielding the guardrail posts and absorbing the impact energy of a sliding, dismounted motorcycle rider.
Bridge & culvert barriers are specifically designed to provide safe vehicle containment and redirection when installed along the edge of an elevated structure.
Crash cushions are installed to shield the blunt ends of safety barrier systems. They are designed to decelerate an end-on vehicle impact over a short distance and feature energy absorbing cartridges or components.
Wire rope safety barrier systems rely upon the tensile strength and deflection of wire cables to contain and redirect errant vehicles. They provide stable vehicle containment and low ride-down decelerations.
Workzone Barriers are used as part of the traffic management plan to protect roadside workers and guide motorists through the construction zone. and are designed for rapid deployment and removal.
Median gates are designed to provide vehicle access during emergencies or road maintenance. When the median gate is closed, it is designed to function as a continuous safety barrier system.
Pedestrian fencing provides a physical barrier that separates pedestrians from moving traffic, reducing the likelihood of vehicle and pedestrian collisions.
