If you have recently had a fire risk assessment carried out on your premises, you may have found that your assessor has raised concerns about travel distances.
It is one of the most common findings in fire risk assessments for commercial and residential buildings, and one that is sometimes met with confusion or scepticism by building owners and managers who are not familiar with the concept.
This article explains what travel distances are, why they matter, what the relevant standards say, and what you can do if your building has been identified as having travel distances that exceed acceptable limits.
What Are Travel Distances?
Travel distance is the distance an occupant must walk from any point within a building to reach a place of safety, measured along the actual walking route rather than in a straight line.
It is one of the most fundamental concepts in fire safety design and one of the most important factors in determining whether the means of escape from a building are adequate.
The rationale is straightforward.
The longer the distance an occupant must travel to reach a place of safety, the longer they are exposed to the developing fire and its products, and the greater the risk that they will be overcome by heat, smoke, or toxic gases before they can escape.
Travel distance is therefore a direct measure of the risk to which occupants are exposed during evacuation, and controlling it within acceptable limits is one of the primary objectives of fire safety design.
What is a Place of Safety?
Before examining travel distances in detail, it is worth being clear about what constitutes a place of safety for the purposes of this analysis.
The ultimate place of safety is a location outside the building and away from the immediate vicinity of the fire, where occupants are no longer at risk from the effects of the fire.
In most buildings, the means of escape is designed to lead occupants through a series of protected zones, each of which provides a progressively higher level of protection, until they reach the final exit and the ultimate place of safety outside the building.
In a multi-storey building, a protected staircase enclosed by fire-resisting construction and fire doors constitutes a relative place of safety, in the sense that occupants who have reached the staircase are protected from the immediate effects of the fire while they descend to the final exit.
Travel distance measurements in multi-storey buildings typically measure the distance from any point on a floor to the nearest protected staircase or final exit on that floor, rather than the total distance to the outside of the building.
What Standards Govern Travel Distances?
The primary guidance on travel distances in England is set out in Approved Document B, Fire Safety, which accompanies the Building Regulations 2010 (SI 2010/2214) and provides guidance on how the functional requirements of the regulations relating to fire safety can be met.
Approved Document B sets out maximum recommended travel distances for different types of premises and different occupancy conditions, expressed in metres.
The distances specified vary depending on whether the occupant has a choice of two or more escape routes or is limited to a single escape route.
Where an occupant has a choice of escape routes in different directions, the travel distance is measured to the nearest exit, and higher maximum distances are permitted because the availability of alternative routes reduces the risk of the sole escape route being blocked by fire or smoke.
Where an occupant is limited to a single escape route, lower maximum travel distances apply, because there is no alternative if the sole route becomes unavailable.
For an office or similar workplace, Approved Document B recommends a maximum travel distance of 18 metres where there is only one direction of escape, and 45 metres where there are two or more directions of escape.
For other common building types, the recommended maximum distances vary.
In residential buildings including flats and maisonettes, the maximum recommended travel distance within a flat to the flat entrance door is 9 metres for a room that opens directly into a circulation space, and shorter distances apply in some configurations.
In shops and retail premises, the maximum recommended distance is 18 metres in one direction only, and 45 metres where two or more directions of escape are available.
In assembly and recreation buildings, the distances vary depending on the nature of the occupancy and the level of risk.
And in industrial premises, higher distances may be acceptable in some circumstances, subject to the findings of the fire risk assessment and the adequacy of other fire safety measures.
It is important to note that Approved Document B provides guidance on compliance with Building Regulations for new buildings and major refurbishments, not a definitive legal standard for existing buildings.
For existing buildings, the fire risk assessor will use the Approved Document B guidance, alongside other relevant guidance documents such as the sector-specific fire safety guides published by the Department for Levelling Up, Housing and Communities and the National Fire Chiefs Council, as a benchmark against which to assess the adequacy of the means of escape.
Where the travel distances in an existing building exceed the recommended maxima, this does not automatically mean that the building is unsafe or that enforcement action will follow.
It does mean that the fire risk assessment must consider whether the excess travel distance is adequately compensated by other fire safety measures, and whether the overall means of escape is adequate for the specific occupancy, use, and risk profile of the building.
Why Does Travel Distance Matter So Much?
The significance of travel distance in fire safety is best understood in the context of the relationship between ASET and RSET discussed in our previous article.
Travel time, which is directly influenced by travel distance, is one of the key components of RSET, the total time required for occupants to escape from the building.
The longer the travel distance, the longer the travel time, and the higher the RSET.
If RSET exceeds ASET, the time available for occupants to escape before conditions become untenable, occupants may be unable to escape safely.
Excessive travel distances therefore directly erode the safety margin between ASET and RSET, and in a building where other aspects of fire safety design are also marginal, they can tip the balance from safe to unsafe.
The risk is compounded in buildings where the fire load is high, where smoke control is limited, where the occupant population includes people with mobility or cognitive impairments, or where the building is occupied during the night when pre-movement times are likely to be longer.
Dead Ends
One of the most significant travel distance concerns that fire risk assessors encounter is the presence of dead ends in the escape route layout.
A dead end is a section of corridor or circulation space from which there is only one direction of escape.
An occupant at the far end of a dead-end corridor has no choice but to travel the full length of the corridor towards the only available exit, even if that exit is compromised by fire or smoke.
Dead ends are particularly dangerous because they can trap occupants who discover that their only means of escape is blocked, leaving them with no alternative route and no means of reaching safety.
The maximum recommended travel distance along a dead-end corridor is significantly shorter than the distance permitted where two or more directions of escape are available, reflecting the increased risk to occupants in these situations.
Where a fire risk assessment identifies dead-end corridors with travel distances that exceed recommended limits, urgent action is typically required, either to provide an additional means of escape that eliminates the dead end, or to implement compensating measures that reduce the risk to an acceptable level.
What Compensating Measures Are Available?
Where travel distances in an existing building exceed recommended limits, it may not always be practical or possible to physically alter the building to bring them within the guidance.
In these circumstances, it may be possible to justify the excess travel distance through the implementation of compensating measures that reduce the overall risk to occupants to an acceptable level.
The most effective compensating measure is the installation of an automatic fire suppression system, typically a sprinkler system, which slows the development of fire and smoke and increases the ASET available to occupants, thereby offsetting the increase in RSET caused by the longer travel distance.
The installation or enhancement of a fire detection and alarm system can also help to compensate for excessive travel distances, by reducing the detection and alarm time components of RSET and ensuring that occupants receive the earliest possible warning of a fire.
The enhancement of smoke control measures, including the provision of natural or mechanical ventilation to escape routes, can maintain tenable conditions in those routes for longer and extend the effective ASET.
Improvements to passive fire protection, including the upgrading of fire doors, the improvement of compartmentation, and the sealing of penetrations through fire-resisting elements, can also help to contain fire and smoke and limit the rate at which conditions in escape routes deteriorate.
And operational measures, including enhanced staff training in evacuation procedures, the posting of staff in high-risk areas to assist with evacuation, and the implementation of more frequent fire drills, can reduce pre-movement time and improve the speed and efficiency of the evacuation process, thereby reducing RSET.
The appropriateness and adequacy of any compensating measures must be assessed by a competent fire risk assessor or fire engineer, who can evaluate whether the measures proposed are sufficient to bring the overall risk to an acceptable level given the specific characteristics of the building and its occupancy.
Single Stairs and Travel Distance in Residential Buildings
The issue of travel distance in residential buildings, particularly multi-storey residential blocks with a single staircase, has received significant attention in recent years, partly as a result of the Grenfell Tower fire and the subsequent review of fire safety guidance for high-rise residential buildings.
Many purpose-built blocks of flats, particularly those built in the mid to late twentieth century, were designed with a single staircase serving all floors, on the basis that the stay put evacuation strategy would mean that few occupants would need to use the staircase simultaneously in the event of a fire.
The Grenfell Tower fire exposed the limitations of the stay put strategy in circumstances where fire spreads externally or where compartmentation fails, and raised serious questions about the adequacy of single-staircase designs in buildings where simultaneous evacuation may be required.
The travel distances within individual flats, from any room within the flat to the flat entrance door, are also a significant concern in some older residential buildings, particularly where large flats with complex layouts result in travel distances that exceed the limits recommended in Approved Document B.
The fire risk assessment for a residential building must consider travel distances both within individual flats and within the common parts, and must assess the adequacy of the means of escape in the context of the specific building and its evacuation strategy.
What Should You Do if Your Assessor Has Raised Travel Distance Concerns?
If your fire risk assessment has identified travel distance concerns, the first and most important step is to take the finding seriously and engage with your assessor to understand the specific nature of the concern and the options available to address it.
Travel distance concerns should never be dismissed as a theoretical issue or as something that has not caused a problem in the past.
The fact that a building with excessive travel distances has not suffered a serious fire does not mean that it is safe.
It means that the risk has not yet materialised.
Your assessor should be able to explain clearly why the travel distance is a concern, what the specific risk to occupants is, and what options are available to address the finding, ranging from physical alterations to the building through to compensating measures and operational improvements.
Where the travel distance concern is significant, you should seek the advice of a qualified fire engineer who can carry out a more detailed analysis of the specific risk and develop a proportionate and justified solution.
And where travel distance concerns are identified, the Responsible Person should ensure that the finding is recorded in the fire risk assessment, that a clear action plan is developed for addressing it, and that progress against that plan is monitored and recorded.
Failing to act on a travel distance concern identified in a fire risk assessment is not just a compliance failure.
In the event of a fire in which occupants are unable to escape because of inadequate travel distances, it is a failure that could have devastating consequences for the occupants and serious legal consequences for the Responsible Person.
We Can Help
At ESI: Fire Safety, we carry out thorough fire risk assessments for all types of premises, identifying travel distance concerns and other means of escape deficiencies and providing clear, practical guidance on the options available to address them.
Where complex travel distance issues require a more detailed fire engineering analysis, we work with specialist fire engineers to ensure that the assessment is thorough, robust, and properly documented.
If you have concerns about the means of escape from your premises, or if a previous fire risk assessment has raised travel distance issues that have not yet been resolved, get in touch with our team today.
Further Reading and Key Legislation:
Approved Document B, Fire Safety: https://www.gov.uk/government/publications/fire-safety-approved-document-b
Regulatory Reform (Fire Safety) Order 2005 (SI 2005/1541): https://www.legislation.gov.uk/uksi/2005/1541/contents/made
Building Regulations 2010 (SI 2010/2214): https://www.legislation.gov.uk/uksi/2010/2214/contents/made
BS 7974:2019 Application of Fire Safety Engineering Principles to the Design of Buildings: https://www.bsigroup.com
NFCC Fire Safety Guidance: https://nfcc.org.uk
Institution of Fire Engineers: https://www.ife.org.uk
This post is intended as a general guide. Travel distance requirements vary depending on building type, occupancy, and the specific findings of the fire risk assessment. Always seek advice from a qualified fire safety professional for guidance specific to your premises and circumstances.
