Key Insights
A deep dive into fire safety for road and rail tunnels in Australia.
Fire safety for road and rail tunnels in Australia is governed by AS 4825-2011. This is the general framework for establishing fire safety systems that are required to provide an acceptable level of safety in case of fire. It provides guidance to the development of fire safety strategy, design, and documentation of fire safety systems for tunnels in Australia.
The aim of tunnel design is to provide an adequate level of fire safety for the tunnel occupants, firefighters, maintenance and other emergency services personnel. Adequate safety is defined as reducing fire risk to an acceptable level, facilitating emergency services, protecting adjoining properties and minimising operations, damage, incidents, costs and environmental damage.
Fire Safety for Road and Rail Tunnels
Classifications
This Standard applies to unidirectional and bi-directional tunnels of various lengths and to tunnels involving vehicles with no drivers such as driverless trains, although special additional considerations may apply. Tunnel classification is provided for the purpose of establishing the preliminary fire safety measures for tunnels with different design characteristics for the purposes of an initial concept design. They are classified according to four criteria:
Tunnel Length:
- Long tunnel (L) Where the length is greater than 120m in the case of road and bus tunnels and 250m in the case of rail tunnel
- Short tunnel (S) Where the length is less than the long tunnels
Traffic Conditions (Road tunnels only)
- High traffic (HT) Where there is a high volume of traffic or high likelihood of congested traffic
- Low traffic (LT) Where there is low volume of or low likelihood of congested traffic
Limitations
Safety requirements are stipulated based on tunnel characteristics and categorisation, typically tunnel length (450m) and traffic throughput (low). This standard does not apply to the following types of tunnels:
- Tunnels that do do not meet the definition of a tunnel in Clause 1.6
- Funicular tunnels
- Service tunnels
- Pedestrian or bicycle tunnels
- Railway and bus stations
- Tunnels for vehicles with no persons on board
Requirements
AS 4825 defines the typical fire safety requirements for long tunnels with low traffic as:
- Portal egress
- Fire-isolated exit
- Portable Extinguisher
- Hose Reels
- Hydrants at portals
- Internal hydrants
- Booster facility
- Water supply
- Deluge system
- Fire compartmentation
- Fire protection of structural elements
While this standard is not specifically intended for existing tunnels, the general principles may be applied to the upgrade of existing tunnels to improve fire safety. Modifications should be treated as building a new tunnel for the interpretation of this Standard.
Fire Safety: Passive Fire Protection for Tunnels
The role of passive fire protection in rail and road tunnels is to allow the structure to withstand the impact of fire and to inhibit the spread of flames, smoke and toxic gases.
Fire compartmentation involves limiting the risk of fire, heat or smoke from spreading throughout the tunnel. It allows fire to be contained, protecting the remaining structure and facilitating occupants safe evacuation.
Fire protection of structural elements involves the use of passive fire protection products to protect structural materials such as steel and concrete used in tunnels from the effects of fire.
Determining the products required for tunnel fire safety systems involves understanding the requirements based on tunnel classification and collaboration between key stakeholders including Fire Safety Engineers, Tunnel Operators and Fire Authorities.
The team at Progressive Materials work with these stakeholders to understand the requirements of the tunnel project, to devise compliant fire safety systems and the passive fire protection products required to meet Australian Standards.
Project Insight: Forrestfield Airport Link
Progressive Materials were engaged to devise a solution to provide pass fire protection for rectification of the Forrestfield Airport Link. A cast iron steel ring known as the SGI lining was installed in the tunnel to reinforce prior damage and it was determined that structural steel protection was required. The challenge was to provide critical fire protection to the iron structure, whilst not impeding into the tunnel with big bulky protection systems.
CAFCO Fendolite® MII from Promat, was supplied and spray applied to the structure to provide the required fire performance. We were able to supply product on the same day the material was ordered.
Speak to our technical consultants
Our expert team can assist with specification and supply of passive fire protection products that comply with the relevant standards of your project. Early engagement is crucial to ensuring compliance, buildability to identify opportunities for significant cost savings by optimising systems.
Contact us to learn more and to discuss the requirements of your upcoming project.
