21 Dec Passengers deserve robust protection
Local and international building codes for typical buildings do not readily address the unique fire safety challenges associated with modern train station design reflects Peter Stephenson, Business Development Director, WarringtonFire whereas fire engineering employs performance based design solutions, where necessary, to achieve the life safety goals and objectives of prescriptive requirements.
NFPA 130, ‘Standard for Fixed Guideway Transit & Passenger Rail Systems’, represents best practice for the fire safety design of train stations, is used extensively internationally, and forms part of the NFPA suite of documents that are understood to be acceptable to Civil Defence, for example in Saudi Arabia. This standard also provides flexibility in the fire safety design to allow the designers to use normal entry/egress routes and components (escalators etc.) in an emergency, something that codes for the design of a typical building would not allow. Consequently, this NFPA standard forms part of the design basis for the metro stations. There are however elements of a station design that are beyond the scope of NFPA 130, so additional codes need to be referenced.
Whilst NFPA 130 focuses on the fire safety design of platforms and concourse areas, the standard must be supported by a Building Code for the detailed design of areas that are ancillary to the platform and concourses. NFPA 101 ‘Life Safety Code’ has been adopted to support NFPA 130 for the fire safety design.
References to and the use of local codes such as the UAE Fire & Life Safety Code 2018, Saudi Building Code or Gulf Code are in response to requests from the relevant AHJ.
London Underground standards have been referenced for evacuation calculations on numerous rail projects and are in line with international best practice.
Demonstrating compliance
Fire engineering employs performance based design solutions, where necessary, to achieve the life safety goals and objectives of prescriptive requirements within documents such as NFPA 130, and provide an equivalent or greater level of fire safety. The life safety goals and objectives of NFPA 130 should be given due consideration for the areas covered by that standard:
• Life safety goals; NFPA 130, Chapter 4.2 (Goals).
• Life safety objectives; NFPA 130, Chapter 4.3 (Objectives).
When deviating away from code guidance a performance based design should achieve both the goals and objectives. This provides a performance based alternative to the prescriptive provisions of the Code. The performance based option is a process that can be used to determine whether the building design satisfies the fire safety goals and objectives specified in the Code. It is not the intention of the performance based approach to replace the prescriptive Code, but to demonstrate an equivalent, or better than, level of safety as the prescriptive guidance (NFPA), and as such provide design flexibility.
The key areas of Performance Based Design revolve around the use of evacuation and CFD modelling to determine the performance of the egress system and the tenability for this period.
The provision of sprinklers in a railway station requires careful consideration. NFPA 130: Clause 5.7.3.1 recommends that automatic sprinkler protection be provided in areas of stations used for the following: Concessions, general storage, refuse rooms and other similar areas with combustible loading, except train ways. Where high ceiling levels are experienced and sprinklers are unlikely to be effective, their removal from the design should be robustly demonstrated to the AHJ with particular consideration given to the fire loading where it is not similar to areas listed in NFPA 130.
The fire strategy for the station under consideration should address credible fire scenario’s and may include the following:
• Train-way Fire – A fire occurring within the train way can occur in one of two ways, from either a stationary train within the station, or from a train arriving already on fire and necessitating evacuation of passengers. A fire which occurs on-board a moving train presents a greater risk to on-board passengers and passengers on the platform compared to a stationary vehicle fire, as the fire will have had time to develop prior to arriving at the station.
• Platform (Baggage) Fire – Fire load on platforms will consist of transient fire loads, mainly luggage. A fire involving such a hazard may not present a significant risk to passengers where the open nature of the platform and the smoke control systems are designed to keep tenable conditions during evacuation.
• Public Area Fire – A fire within the public areas of the station can occur from two primary types; fixed or transient fire hazards.
• Transient Fire Hazards – Transient fire hazards include luggage or rubbish containers. These will present a relatively low fire load however are unenclosed and open to the concourse.
• Fixed Fire Hazards – Fixed fire loads can consist of retail concessions, ticket offices etc. These hazards may be enclosed in fire resistant construction with active protection including smoke control, fire shutters and automatic sprinklers.
Fires occurring within such locations will initially only present a risk to occupants within the compartment of fire origin. Those within the main concourse will not be placed at immediate risk.
• Retail Area Fire – Retail areas may often be split into a number of smaller units, rather than a single destination retail unit (department store). As such, phased evacuation of the retail areas and main station could be considered, focussed on the level of management available within the large retail unit.
• Car Park – A fire in the multi-storey underground car park would be separated from the main station by fire rated compartmentation and would present a risk to the people within the car park and the adjacent accommodation only and could be considered as a separate evacuation zone to that of the main station.
• Ancillary Accommodation Fire – All non-public areas, ancillary to the public concourse and platform areas will be separated from public areas with fire resistant construction. A fire occurring in such areas will not immediately affect the greater concourse or platform population.
Fire safety management – back to basics
To ensure successful fire safety management at a major transportation hub it is vital to develop a solid understanding of the key elements that provide a foundation upon which to build. The scope and nature of fire safety along with the moral, legal and financial reasons for promoting good standards of safety should be transparent to all relevant stakeholders. The legal framework for the regulation of fire safety in conjunction with the legal and financial consequences of failure to manage safety correctly must be understood by all persons with designated responsibilities.
The failure to manage safety adequately all too often results in death or injury and loss of business confidence, which can have a significant impact on the physical and economic wellbeing of society. A serious fire in a workplace associated with inadequate management of fire safety can begin a spiral of events that may result in total business failure.
Regardless of the type of organisation, its activities and the specific management issues that it faces, clear unequivocal policies relating to fire safety matters are needed in order to establish effective organisational control. A policy is the basis of an organisation’s management strategy; providing direction, enabling it to organise, plan, set targets and implement its organisational objectives.
However, a policy in itself cannot be effective unless the words are turned into actions. Over a number of year’s a variety of management systems have been produced, any of which can be utilised to assist in establishing a safety management system. Many organisations are familiar with BSEN ISO 9001, a quality management system which can be accredited by an external organisation.
The purpose of risk assessment is to assist an employer and/or a ‘responsible person’ to identify the preventive and protective measures required to comply with the law, codes/standards and the AHJ requirements and in doing so, ensure, as far as reasonably practical, the safety of their workforce, premises and those around them who could be affected by their activities. Because of the fundamental role risk assessments play as a starting point for developing safety management systems, they must be conducted systematically. A systematic approach will help satisfy the law and ensure that nothing which could present a risk is inadvertently omitted and can be relatively easily achieved by a straightforward progression through a number of logical steps.
There are a number of different methodologies that are currently used to achieve a systematic approach to risk assessment. In essence the fundamental themes are:
• Identify the hazards
• Decide who might be harmed and how
• Evaluate the risks (in terms of likelihood and severity) and decide whether the existing precautions are adequate or whether more should be done
• Record the significant findings
• Review the assessment and revise if necessary.
There are a number of methods for evaluating risk. The method applied for any particular risk will depend on a number of factors, such as the complexity of the activities carried out and the type and nature of the workplace. For many of the day-to-day risks that people in the workplace are exposed to, including fire, a simple qualitative assessment will suffice, for more complex risks a quantitative or semi-quantitative assessment may be needed, for example;
• Qualitative analysis – describes the quality of risk using words.
• Quantitative analysis – quantifies the risk with numerical data.
• Semi-quantitative analysis – uses numbers to quantify qualitative data.
The key to effective safety management, once the risks have been identified, is to establish and implement a control strategy. The control measures that are implemented to secure the safety of all those at work or who may be affected by the work or work processes should reflect the local requirements, as a minimum standard, and any technological advances that have been made.
It is therefore essential when considering the fire risk assessment process to include not only the task-based or operations-based risks, which may cause a fire, but also the building risks that may prevent persons responding and being able to escape to a place of safety in the event of a fire. The key principle of the risk assessment process is to enable those completing a fire risk assessment to ensure that it is both suitable and sufficient.