Fire Safety and Evacuation Strategy in Automated Underground Rail Systems

Automated underground rail systems are increasingly adopted worldwide to deliver high capacity, reliable public transport in dense urban environments. These systems operate in constrained underground settings where fire and smoke behaviour, evacuation options and emergency response differ fundamentally from those associated with above-ground buildings.

Fire safety in underground rail systems is typically addressed through project-specific fire engineering assessments supported by Australian and international standards. While these assessments establish a robust technical basis for life safety, real-world outcomes are also strongly influenced by passenger behaviour, operational readiness and firefighter intervention. Where these elements are not well aligned, the consequences can be severe.

This article explores fire safety and evacuation principles for automated underground rail systems from a fire engineering perspective. It aims to raise awareness of why evacuation strategies may differ from public expectations, why coordination between design and operations is critical and why stakeholder and public understanding play a vital role in achieving safe outcomes during emergency events.

Typical Configuration of an Underground Rail System

An underground rail system typically comprises inbound and outbound rail tunnels, underground stations and associated ancillary spaces forming a continuous passenger environment. Trains operate within single or twin-bore tunnels, often extending several kilometres between stations. Typically, a separate maintenance and stabling facility will be located above ground.

Underground stations generally include platforms connected to concourses and surface entrances via stairs, escalators and lifts. These spaces are designed to accommodate high passenger densities and incorporate ventilation systems, plant rooms, emergency egress routes and fire safety infrastructure.

Rail tunnels are typically provided with evacuation walkways adjacent to the tracks, emergency lighting, wayfinding signage and cross-passages linking parallel tunnels to places of relative safety. Mechanical ventilation systems are designed to manage smoke movement and heat during fire events.

In automated systems, train operation and emergency management are controlled by centralised control centres. Passenger instructions are delivered through public address systems, passenger information displays and other fixed communication infrastructure rather than onboard staff. As a result, fire engineering assessments consider the rail system as an integrated operational environment rather than a collection of isolated spaces.

Why Public Awareness Matters

Most people are familiar with building evacuation principles: follow exit signage, use stairs and evacuate directly to open air. In underground rail systems, however, the safest response during a fire may not be immediately intuitive.

In the event of a fire within an automated rail system, the default instruction would be to continue to the next station. Only under specific conditions, such as mechanical failure or severe fire scenarios, would evacuation into the tunnel environment be initiated.

Passengers may be instructed to remain on board temporarily or allow passengers to move between carriages away from a fire source or detrain for evacuation via dedicated tunnel walkways. The trains may or may not have staff on board to provide direct assistance. Without prior awareness of evacuation procedures in the event of fire, these instructions can cause confusion or hesitation, potentially impacting safety outcomes. 

If passengers are unfamiliar with these strategies, instructions provided during an emergency can appear counterintuitive, leading to hesitation, non-compliance or unsafe self-evacuation attempts. Improving awareness of how and why evacuation decisions are made helps build trust in the system and supports safer behaviour when it matters most. It is equally important that the general public understands, at a high level, how evacuation is managed and why instructions during an emergency may differ from their everyday expectations.

Regulatory and Guidance Framework

Fire safety strategies for underground rail systems in Australia are informed by a combination of Australian and international guidance, including but not limited to:

• AS 4825:2011 – Tunnel Fire Safety
• NFPA 130:2023 – Standard for Fixed Guideway Transit and Passenger Rail Systems
• National Construction Code 2022, Volume One – Building Code of Australia
• Australian Fire Engineering Guidelines 2021

These frameworks collectively recognise the unique characteristics of underground transport environments, including long travel distances, constrained exits and reliance on mechanical ventilation. They support performance-based approaches that prioritise life safety through demonstrable tenability rather than prescriptive solutions. This provides project specific risks and fire safety systems to be assessed holistically.

Fire Engineering Approach

Fire engineering assessments for automated underground rail systems evaluate whether life safety objectives can be achieved under a range of credible fire scenarios. These assessments account for the interaction between fire dynamics, smoke movement, ventilation performance, infrastructure geometry, operational response and passenger movement.

Key parameters commonly assessed include:

• Fire size, heat release rate and growth characteristics
• Smoke spread within tunnels and stations
• Tenability criteria along evacuation paths
• Passenger movement speeds and flow capacity
• Available evacuation time relative to required evacuation time
• Fire brigade intervention time and protection to firefighters

Unlike prescriptive approaches that may be applied to buildings, fire engineering assessment enables system-wide evaluation, recognising that evacuation may involve horizontal movement, phased relocation or delayed egress depending on conditions.

Tunnel Evacuation Strategy

Tunnel evacuation in underground rail systems is generally considered a controlled and conditional response, rather than an immediate default action. Fire engineering assessments determine whether passengers are safer remaining on board, relocating to a station or evacuating via tunnel infrastructure.

Tunnel evacuation strategies typically incorporate:

• Continuous evacuation walkways between or adjacent to tracks
• Cross-passages connecting parallel tunnels
• Ventilation systems designed to manage smoke and heat

From an engineering perspective, these elements are assessed to ensure that tenable conditions can be maintained along evacuation routes for the duration required. For passengers, however, walking through a tunnel environment may be unfamiliar and counterintuitive, highlighting the importance of pre-incident awareness.

Station Evacuation Strategy

Underground stations function as primary evacuation nodes and are designed to accommodate large passenger flows under emergency conditions. Fire engineering assessments evaluate both horizontal and vertical movement, ensuring that congestion does not compromise tenability.

Typical station evacuation considerations include:

• Horizontal movement along platforms away from the fire source
• Access to stairs and escalators
• Smoke control within platform and concourse spaces
• Controlled discharge to the outside

Use of escalators during fire events, including shutdown or controlled operation, is an important aspect of passenger expectation management. Evacuation strategies would typically account for persons with reduced mobility through the provision of lifts where feasible, refuge areas and assisted evacuation procedures.

These strategies may differ from public expectations of immediate evacuation to the outside, particularly where conditions within the station remain tenable and evacuation routes must be managed to prevent bottlenecks.

Autonomous Operations, Communication and Human Factors

The absence of onboard staff in automated rail systems places greater emphasis on communication systems and human factors. Passenger guidance is delivered through centralised control centre using public address (PA) systems, passenger information displays and visual messaging.

Fire engineering assessments increasingly consider human factors, including:

• Passenger response to automated instructions
• Trust in remote authority during emergencies
• Decision-making under uncertainty and stress
• Equity of communication for people with reduced hearing or vision

Effective evacuation messaging must be clear, timely and accessible. This may include the integration of PA systems with passenger information displays, improved acoustic performance in underground environments, visual cues directing passengers toward exits or refuge areas and the application of universal design principles. Familiar daily-use systems, such as platform displays, can be leveraged to reinforce evacuation messaging during emergencies.

Fire engineering assessment takes the above operational model into account by evaluating how communication systems support passenger decision-making and compliance during emergencies. Close coordination with emergency services is also critical to ensure timely intervention and effective incident management.

Stakeholder Engagement and Community Confidence

Fire incidents in underground rail systems are rare, but planning for them is essential. Through robust fire engineering assessments, integrated system design and clear evacuation strategies, automated underground rail systems are engineered to protect life and maintain public confidence.

Fire safety outcomes are influenced by the coordinated efforts of designers, engineers, operators, emergency services and regulators. Continued stakeholder engagement during design and operation ensures that evacuation strategies are technically robust, operationally feasible and aligned with emergency response capabilities.

Beyond technical stakeholders, public awareness plays a crucial role. Unlike occupants within buildings, rail passengers may have limited understanding of underground evacuation principles. In automated systems, the lack of visible staff may further increase uncertainty. Improving community-level understanding of how evacuation works in underground rail systems can enhance compliance with instructions and reduce panic during emergency events.

While fire engineering assessments provide confidence that evacuation strategies meet life safety objectives, their effectiveness ultimately depends on human behaviour. The divergence between engineered evacuation strategies and public expectations presents a risk that cannot be addressed through design alone. From a community perspective, transparency and education play a vital role in building confidence. Clear, consistent messaging about what passengers should expect during emergencies can complement engineering controls and improve overall system resilience.

From a personal perspective, the effectiveness of public awareness initiatives is evident in practice. Every time I visit my hometown of Seoul, South Korea, I found myself repeatedly watching evacuation videos displayed alongside passenger information displays on the subway – on the platforms and inside the trains. These videos demonstrate what evacuation may look like under realistic smoke conditions and run continuously, reinforcing expected behaviours through repetition. Importantly, they rely on visual communication rather than language, making them immediately accessible to local passengers and international visitors alike. This provides a compelling example of how clear, universally understood messaging can significantly enhance passenger preparedness and confidence.

Building Safer Systems Through Knowledge

Improving awareness, communication and trust bridges the gap between engineered solutions and human behaviour. By aligning design intent, operational procedures, firefighter capability and passenger understanding, underground rail systems can achieve safer, more resilient outcomes.

Jensen Hughes has extensive experience supporting underground rail projects worldwide, delivering fire safety strategies that align regulatory requirements with operational realities. Through fire engineering expertise and stakeholder collaboration, Jensen Hughes helps clients balance life safety, system resilience and business continuity across complex rail environments.

For further discussion on underground rail fire safety or to learn how Jensen Hughes can support the development and assessment of fire safety strategies for rail infrastructure projects, we welcome engagement with industry partners and stakeholders.