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Fire Engineering in Rail Projects in Australia
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Fire Engineering in Rail Projects in Australia
How fire protection engineering is being incorporated into a massive rail network

By Joe Paveley, Ph.D., ARUP | Fire Protection Engineering


In Australia, a major expansion of the rail network is underway, with new routes and upgrades to existing facilities. Much of the investment has been in improving and expanding city services, including increasing the capacity of existing lines. Most rail lines are aboveground; however, there is increasing demand for underground routes in dense, urban areas.

A recently completed underground rail line, the Chatswood to Epping Rail Link in Sydney, is a 12 km-long twin tunnel with three new stations connecting two existing stations. Further expansion has been planned for Sydney, with new lines above and below ground. Other cities, including Melbourne, Brisbane and Perth, are also expanding their networks.


Australia uses heavy rail systems in urban areas, with time tabled train operations and trains suited to suburban commuting. Metro services have been proposed for the more densely populated city centers either as completely new systems or by changing the train car design and operations to increase passenger load and reduce the transfer time at platforms.



In Australia, the safety assurance process is now a fundamental part of rail system design and operations. This is a risk-based process that covers all design aspects that affect safety, including signals, track design, occupational health and safety, security (including terrorist risks) and fire protection engineering. Rail regulators typically review risks as a whole, so they are keen to keep fire safety risk slow. Fire protection engineers can expect their fire strategies to be challenged in detail. Prescriptive codes may give some direction for fire strategy, but reliance on these alone may not demonstrate that the required level of safety has been achieved.



The ALARP (As Low as Reasonably Practical) and related risk processes are generally used to assess safety. Hazards are identified and risks assessed for design, construction and operational safety. The risks are ranked using consequence and probability descriptors to inform the design team of the key risks. A generic example of a risk ranking matrix is shown in Table 1. Table 2 shows the required actions for the risk rankings.



There have been few fatal rail fires in Australia, and none of the same severity as King's Cross, London, 1987.1 There are several reasons for this, but an important factor is operational staff acting quickly to prevent the escalation of fires. The challenge is to maintain an acceptable level of fire safety with changing operations, greater passenger numbers, and an expanding rail network.


In Australia, buildings must comply with the Building Code of Australia (BCA).2 The prescriptive provisions do not address stations adequately, particularly platforms with large travel distances and escalators used for egress, nor do they address other issues such as electrical hazards and train operations.


For tunnels, a new draft Australian Standard3 was issued in 2009 for comment. This generally adopts a risk-based approach, providing high level guidance, but avoiding prescriptive requirements.


NFPA 1304 is often used as guidance for station and tunnel fire safety design in Australia, although it must be adapted carefully to suit local rail operations and fire safety industry practice.


Rolling stock fire safety design is typically addressed through a range of fire safety standards and guides, including in-house standards, ad hoc tests, and references to other standards such as BS 6853.5 Some rail authorities are now updating these standards to take into account developments in materials testing and fire protection engineering methodologies generally.


The International Fire Engineering Guidelines (IFEG)6 set out the fire protection engineering process, with some adaptation to align with the safety assurance process. A risk-based approach is often adopted for the fire safety issues in rail projects,with codes providing supporting guidance for design solutions.



Fire protection engineering, as a discipline, is new to the rail industry. Prior to its involvement, various disciplines would develop fire safety designs, often in isolation of others, and not always with specialist fire safety knowledge. This led to repeating previous designs, without understanding the background. Code interpretation was often carried out independently, with parties using different assumptions. Often, the rolling stock, tunnel and station designs were developed in isolation of each other. There was coordination of some key design elements, such as the kinematic envelope for trains, but with less integration for fire safety. With this approach, some fire hazards may have been left uncontrolled for some elements or over designed in others.


There has been performance-based design on infrastructure projects for nearly 15 years; an earlier example is Sydney Olympic Park,which opened in 1998. The scope for fire protection engineering has expanded, becoming the means to integrate fire safety design solutions, as well as solving specific design problems. This has occurred in parallel with new investment in the rail industry and the introduction of the safety assurance process, as well as the introduction of performance-based fire safety design. Many clients see the value in fire protection engineering to develop a fire strategy early, setting the parameters for the design of the tunnels, rolling stock and stations.



An essential part of the process is defining the fire protection engineering objectives. These include safeguarding people from injury due to a fire, avoiding fire spread to adjacent property and facilitating emergency services' activities. A safety-

by-design' approach is adopted for all design elements to include consideration to installation, operation and maintenance risk. Other objectives include operational continuity and reliability, which can involve maintaining operations after a relatively small fire, maintaining operations in degraded mode after a significant fire, and implementing a process to avoid escalation of a fire. These operational objectives require early detection and response to incidents, including a robust communication strategy.


A risk-based approach has been used for the selection of fire scenarios, categorising the scenarios as Base Case Design Fires; High Challenge Design Fires; and Extreme Events.

The categories determine the safety margin which is to be applied to the results, as shown in Figure 1.7 The fire scenarios can include a combination of fire sizes and occupant numbers.


The identified scenarios are assessed in terms of the Sub-Systems' defined in the IFEG, namely:

  • Fire initiation and development and control.
  • Smoke development and spread and control.
  • Fire spread and impact and control.
  • Fire detection, warning and suppression.
  • Occupant evacuation and control.
  • Fire brigade intervention.


Rail fire safety is part of a dynamic system. In a fire or other emergency, the number of passengers on a train, number of trains in a tunnel and initial response of the rail operator depend on the system operation. The best place for evacuation is the station, where there is the capacity for the safe, rapid evacuation of a train. Evacuation of passengers from tunnels can be hazardous, even without a fire; therefore, it is better if a train with afire can keep moving to a station. Until the train arrives,reasonable conditions in the cars are required by limiting fire and smoke spread. In Australia, specification of material fire performance varies, although is typically by reference to BS 6853 with additional local requirements. Newer international codes, such as EN 45545,8 are beginning to be adopted. The Duggan method9 is often used as a simplified method to limit the train car interior heat output. This can over predict the actual maximum fire size, but in the absence of more detailed analysis, provides a fire size as a common point of reference for train material specification and smoke ventilation design. A more detailed analysis of fire growth in existing rolling stock was conducted by Coles, Wolski and Taylor.10


The resilience of other train systems can improve fire safety, for example:

  • Fire rated floor to the passenger compartment, to protect passengers from an under car traction or brake fire;
  • Two cars to have independent power connection via fire rated (or fire separated) cables to power transmission units;
  • Multiple motor units, so that a train can continue to the next station, even with failure of one or two units.

These features are important in allowing a train to continue safely to the next station, even with a severe fire affecting one car.


New rolling stock generally has automatic fire detection (in car and under car), CCTV to all areas of the car interior, and various communications systems, such as public address, passenger information displays, and passenger emergency information systems.

A difficulty often encountered is older rolling stock that is run through tunnels that have fewer fire safety features and less robust power and communications systems. Older trains, or trains not specified for underground use, may not have the fire safety features described above. In these cases, it is less certain that a train could reach the next station, or that reasonable tenability could be maintained in the passenger cars, while travelling to a station.


On some systems, reviews have been conducted on whether staffing numbers can be reduced, including operating the trains without an attendant or driver. In these cases, emergency egress response needs to be assisted or directed by a remote operator in a central control room. This requires robust communications, with levels of redundancy in the train, tunnel and station. The fire protection engineer must understand how these systems interact to be able to develop fire scenarios.


When a fire-affected train travels on to the next station, a reasonable degree of safety must be provided. The omission of inter-car doors has been examined to varying degrees by many operators, who are keen to have an open train car design, in part for better security. This can lead to greater smoke spread between cars. This could impact tunnel egress design if there is a significant risk due to smoke while a train continues travel or due to a train halting in a tunnel. The rail tunnel systems in Australia are urban, with less than 6 minutes travel time between stations; therefore, the risk is generally low.



There are many factors that affect safe egress from stations, including smoke control and occupant behavior. A key design issue is predicting the occupant load numbers in an emergency and acceptable evacuation times; typically, the methodologies in NFPA 1304 are used. Passenger numbers vary with different scenarios, and this is addressed in NFPA 130. NFPA 130 requires calculation of the occupant load with one missed headway; however, beyond that, there are a variety of assumptions used - such as crush-loaded trains arriving from both directions, rather than train loads based on patronage estimates. This can lead to differences in occupant load estimates. There is also much discussion about the 4-minute and 6-minute target evacuation times. There is often a dogmatic attitude towards these targets, even with open air stations, despite NFPA 130 allowing these time periods to be varied.


The occupant loads and fire scenarios can be categorized into design basis, sensitivity and extreme. The evacuation time can be better assessed using levels of service, with maximum time limits for individuals to be held in a queue at restricted points along the egress route. This is also compared against the conditions achieved by the smoke control system. This provides a better means to design and assess evacuation strategies than attempting to interpret the exact meaning of four clauses in NFPA 130.


One of the challenges with evacuation analysis has been to understand the effect of stations at depth. Some stations have been planned up to 40 m deep. This can lead to challenges on the movement speed of occupants if they need to climb fire stairs or if using long escalator runs. A reduction in speed is likely, and stairs are likely to become crowded, possibly crush-loaded, as the flow slows or people stop to rest at upper levels. There is limited information for movement speeds during continuous climbs at depth.


Solutions can involve factoring in reduced flows and providing extended landings to provide resting spaces. Proposals have been developed for the use of lifts as a large-capacity system for general evacuation, as an alternative to stairs and escalators. This is allowed in NFPA 130, and has been adopted for some station designs internationally; however, in Australia this has only been used for disabled passengers.


Egress analysis can use spreadsheets using flow and walking speed data from various sources or computer modeling. The computer modeling can be used to demonstrate overall flow through the evacuation routes. It can also be used to visualise the effects of some design options.


Smoke analysis at platform level can be done by computational fluid dynamics modeling.


The design and the modeling become more difficult when platform screen doors (PSD) are introduced. In a fire, there can be confusion, crowding on the platform, and smoke in the train cars. It can be unclear if all passengers are off the train, and whether the PSDs can be closed to contain smoke.


The smoke control system design must allow for the PSDs to be open during the fire. The gaps between the PSDs and the train are narrow, less than 100 mm typically; therefore, the over track exhaust (OTE) system will extract little smoke via this gap. Any smoke from a train is likely to enter the station platform area, and a larger smoke extraction system is required at a high level over the platform.


Design options are available to make better use of the OTE, such as openable dampers above the PSDs to draw some smoke from the platform area into the trackway OTE; however, these can conflict with other design requirements, for example the damper opening conflicting with deep beams over the PSD. This issue needs careful attention to provide a practical design solution.



The probability of a train failing in a tunnel due to fire is low, although the consequences are high if it were to involve a major fire involving a car interior.


Walkways and equipment must be kept to a safe minimum width to avoid increasing the tunnel diameter as part of an economic design. Evacuation of a crowded train in a tunnel can be slow.


In rail tunnels, a longitudinal smoke control system can be provided to protect passengers upstream of a fire. Typically, the downstream condition is taken to be untenable and ignored. This may be deemed acceptable if the most likely scenario is considered to be an under car fire. With a fire-rated floor, passengers would be able to walk over the fire in an upstream direction.


A major fire involving a car interior has a lower probability; however, usually, there will be people downstream of a fire. Consideration should be given to this scenario. If a serious train fire involves a car interior, then occupants are unlikely to be able to walk past the fire They would need to escape through the downstream smoke. In Australia, this issue requires assessment as part of the safety assurance process. This requires a more detailed assessment than simply using 10 m or 7 m visibility as acceptance criteria. The effects of visibility on egress need to be assessed, but ten-ability must be assessed based on the effects of temperatures and gases using a range of fire sizes. The risk may be determined to be low through detailed analysis; however, if the risk is significant, then additional measures are required.


A practical risk-reduction measure is reducing the spacing of the cross passages, thus reducing the distance required to travel through smoke. Cross passages provide an alternative path for passengers to move away from the incident tunnel to the non-incident tunnel and provide additional means for fire brigade personnel to reach the incident. Australian Standards do not have particular requirements for cross passages, although cross passages every 240 m have been used as adapted from NFPA 130. This tunnel standard requires a smoke control system for tenable conditions along the egress route. Typically, this is with a longitudinal smoke control system. to avoid back layering. A longitudinal smoke control system will normally generate air flow at less than 2 m/s upstream of the train. It is not intended to maintain tenable conditions downstream of the fire, but may dilute smoke sufficiently to protect occupants from smaller fire sizes.


With increasing cross passage distances, it becomes more difficult for the occupants downstream of afire to reach safety and for firefighters to access, or retreat from, a fire. However, with well designed rolling stock, there can be reduced probability of the failure of a train leading to passengers needing to escape downstream of a fire.


In Australia, it is unlikely that a distance between exits or cross passages greater than 240 to 300 m a passenger rail tunnel would be accepted unless it can be conclusively demonstrated that tenable conditions are possible downstream of a fire up to the maximum size. Smoke temperatures would need to be limited to enable occupants to travel the distances required without injury. Large cross passage spacing could lead to a significant change in smoke control, possibly even a smoke extraction system similar to that now provided in road tunnels in Australia.


Joe Paveley is with Arup.



  1. Fennel, D., "Investigation into the King's Cross Underground Fire," Her Majesty's Stationary Office, London, 1988.
  2. Building Code of Australia - Class 2 to Class 9 Buildings - Volume 1, Australian Building Codes Board, Fyshwick, ACT, Australia, 2008.
  3. DR AS 4825, "Tunnel Fire Safety," Standards Australia, Sydney, 2009.
  4. NFPA 130, "Standard for Fixed Guideway Transit and Passenger Rail Systems," National Fire Protection Association, Quincy, MA, 2010.
  5. BS 6853, "Code of practice for fire precautions in the design and construction of passenger carrying trains," British Standards Institution, London, 1999.
  6. International Fire Engineering Guidelines, Australian Building Codes Board, Canberra, Australia, 2005.
  7. Johnson, P., Gildersleeve, C. & Boverman, D., "Design Fires - How Do We Know We Have Them Right?" International Conference - Charting the Course, Society of Fire Safety, Melbourne, Australia, 2009.
  8. EN 45545, "Railway Applications. Fire Protection on Railway Vehicles," European Committee for Standardization, Brussels, 2010.
  9. Duggan, G., "Usage of ISO 5660 Data in Railway Standards and Fire Safety Cases,"Fire Hazards, Testing, Materials and Products, Shrewsbury, Shropshire, UK, 1997.
  10. Coles, A., Wolski, A. & Taylor, R. "Rolling Stock Fire Performance: Heat Release Rates with Advanced Computer Modeling," Fire Protection of Rolling Stock 2009, VIB Events, London, 2009.

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