21 Dec Planes, trains & automobiles
The Middle East continues to be one of the most promising regions in the global aviation market writes Peter Stephenson, Business Development Director, Warringtonfire. Other regions and countries, such as Asia Pacific (Singapore, Hong Kong, Vietnam, Thailand) and Africa are developing and maturing as business and leisure destinations the connectivity through airports, rail/metro and road networks continues to expand. Within the UAE the 2020 Expo is drawing closer and the infrastructure enhancements are well developed along with the construction on the Expo site itself.
The coming together of planes, trains and automobiles at major airport terminals highlights the diversity of risk and occupant characteristics the fire engineer needs to consider on these types of project. The severe fire at the Liverpool Waterfront Car Park in the UK on 31st December 2017 highlights the changing risk profile presented in multi-storey car parking facilities. The type of vehicle using these facilities varies around the world from region to region and with the current innovation in the design of motor vehicles the fire load can vary considerably from location to location. Ensuring a full understanding of a buildings current risk profile and keeping abreast of innovation will allow an assessment of future risks to ensure public safety and business continuity which is a high priority at transportation hubs.
When looking at the functional requirements of the many stakeholders involved in the efficient operation of an airport, the fire safety design presents numerous challenges for the fire engineer. Similar challenges can be found in other large mass transportation buildings, such as railway and metro stations, however there are few building types that have complex operational support systems to enable the building to function (retail, security, customs, baggage handling etc.) whilst safely ensuring a positive customer experience. Key architectural aspirations to optimise this customer experience encourages large open spaces for the public and retail areas and efficient operational design for back-of-house areas. To ensure an optimum design solution can be achieved that satisfies the client’s aspirations and also Civil Defence (Authority Having Jurisdiction), a robust fire strategy should be developed which, in many cases, will follow performance based fire engineering techniques whilst considering compliance with local codes.
As part of the development of a fire strategy, adopting the process outlined in British Standard (BS) 7974 (Application of Fire Safety Engineering Principles to the Design of Buildings – Code of Practice) can assist all members of the design team and relevant stakeholders (airlines, terminal operators, security services etc.) work towards the common goal of a safe and operationally efficient airport.
Fire safety objectives & acceptance criteria
As part of the client requirements and initial design brief, the fire safety goals and objectives for a transportation project should be discussed in detail with the client and the approving authority (AHJ), to ensure all requirements are captured and an agreed set of acceptance criteria is established prior to the development of the fire strategy.
Within an airport environment, one of the key client requirements is that the building operates and functions as safely and smoothly as possible to ensure a positive customer experience. When considering an airport terminal building, this means the efficient processing of passengers with the minimum delay possible ensuring that security lines between airside and landside are maintained. This is a major challenge to be addressed within the fire strategy and requires consultation and input from all members of a design team and relevant stakeholders because once on the airside (i.e. departures) side of the terminal, a passenger or object (such as luggage) has cleared security and is deemed safe for a flight departure. This boundary between airside and landside may be formed by solid walls, partial walls/screens, doors or simply a space occupied by staff and x-ray/security equipment.
The position of this demarcation needs to be fully understood, as it needs full consideration when developing the evacuation strategy, including the provision of directional escape signage and zoning of fire safety systems.
Fire strategy and fire engineering process
As previously mentioned, airport design may necessitate the adoption of a fire engineered approach as opposed to
strictly following the recommendations of prescriptive code guidance. The framework contained in BS 7974 provides for the application of fire safety engineering and is similar in that regard to the processes detailed in other performance-based design guides. BS 7974 recommends four main steps in the design process, namely: qualitative design review (QDR); quantitative analysis of design; assessment against criteria; reporting and presentation of results.
These stages provide important input into the development of a robust fire strategy and it is during the QDR stage where the parameters that influence the fire safety design are discussed and agreed. Any key items that are not identified during the QDR, can impact the design development and be a risk to the project.
The team formulated to carry out this process should be led by the project fire engineer(s) and include clients, architects, civil and mechanical engineers, the Airport Fire Department and contractors (if appointed). The composition of the team may include other stakeholders and may vary from project to project.
Review of architectural design, occupant characteristics & fire hazards
As part of this review BS 7974 advises that individual areas of the building should be considered in relation to the architectural design and occupant characteristics.
The passenger experience and interaction from first to last impression of the airport is key to the architectural design aspirations. The fire strategy must compliment this process and the resultant architectural design often consists
of large and high open spaces front-of-house for the public, with little or no physical separation between each area. This presents numerous fire safety challenges but allows a smooth transition for passengers from area to area, for example at departures, check in, security, retail etc., and the reverse for arrivals, including immigration, baggage pickup, retail, arrivals and onwards travel.
Security and immigration processing results in a one-way directional flow and these areas should be designed
to accommodate this process, and the mixing of occupants at different stages in their journey through the airport must
be avoided. The critical area in the airport terminal is the landside to airside line. The evacuation strategy must accommodate this, and prevent mixing of processed and unprocessed passengers, as well as a major reprocessing of passengers in the event of an evacuation.
The terminal `open spaces’ may be subdivided from an evacuation perspective to control safe egress and minimize possible disruption. Where no physical barriers are provided, the strategy may rely on active smoke control systems and fire hazard and control strategies within the fire safety design. The identification and understanding of fire hazards and how they are mitigated are therefore central to the fire safety design. A full understanding of the fire load/hazards within an airport should be well understood and defined to ensure appropriate fire safety systems are incorporated into the design.
A key area of an airport terminal that requires special consideration is the baggage handling area. This process should consider the passage of luggage being sent to the aircraft from check-in areas or the receipt from the aircraft and subsequent dispatch to the baggage reclaim carousels. Challenges generally encountered in this area include: maintaining compartmentation between the handling hall and other parts of the terminal, appropriate means of escape signage in a highly complex environment, and ensuring acceptable travel distances for the trained staff occupying the space(s).
Fire loads and credible fire scenarios need to be considered and agreed during the QDR as these will influence many of the fire protection systems required. The flexibility of retail requirements should be fully considered as this is a key revenue steam for the terminal operators. Unrealistic fuel loads and controls contained within a fire strategy may cause design and implementation problems, resulting in an unrealistic approach as a design basis for fire systems, hence the need for engaging relevant retail stakeholders in the QDR team.
Fire service access
In large terminal buildings and across the airport, the responding fire department/service typically require a single control point to receive a briefing from airport staff on their arrival at an incident to make an assessment prior to implementing their tactical response. From the access location(s), the first responders need quick and easy access to the incident floor from a protected route within a safe distance of the incident and with an adequate supply of water. The means in which they cross the airside/landside line is, therefore, an important consideration.
A Fire Command Centre (FCC) provides an operational hub within which it will be possible to receive live information from the life safety systems, including the CCTV cameras across the terminal/site. The FCC will be separated from the remainder of the terminal by fire resisting construction and should have a dedicated access route direct to open air.
The FCC should be provided with control panels for each smoke control and evacuation zone, which allows full control of an evacuation of the incident area. An evacuation can be phased on an automatic or manual basis, or the decision can be taken to simultaneously evacuate the entire terminal from the control room, if considered necessary. In addition, a microphone is provided with which direct announcements can be given to the building occupants.
The users of an airport terminal consist of a broad range of nationalities, mobility, family groups, single travellers, all with a wide range of travel experience. Their key focus is on either a departing flight, or reclaiming their luggage on arrival and leaving the airport in a timely fashion. An understanding of this behaviour should be a key to a successful evacuation strategy.
With a focus on their processing within the airport, and during peak times the high numbers of occupants being present, a simultaneous evacuation policy can be unrealistic and even unsafe. A phased approach, where a limited number of evacuation zones actually evacuate during an incident, is preferred. This requires that the remaining building zones are large enough to safely accommodate the anticipated occupancy level(s).
Prescriptive codes assume floor space factors, and resulting exit width requirements for egress. For airports, the occupancy is far more complex, and subject to detailed quantifying by the airport planning team. The fire safety engineer can therefore determine the egress requirements using passenger numbers that are based on the predicted passenger flow through the terminal as dictated by the scheduled arrival and departure of flights. The number of staff supporting the airport operations, as well as airline staff, must also be included, and these too are subject to peak flows during a working day.
The response of people within the building upon hearing an evacuation message is another factor that the design team must take into account, especially if an ASET (Available Safe Egress Time) vs. RSET (Required Safe Egress Time) assessment is being undertaken. PD 7974-6 (Human factors: Life safety strategies – Occupant evacuation, behaviour and conditions) describes items that will have an impact on the pre-movement time of occupants, which include the possession of luggage, presence of family groups, language barriers and security restrictions.
The potential for persons with reduced mobility, religious groups etc. should also be examined for local conditions to determine any additional requirements that would need to be included within the design. The key to all of the above is a competent trained fire safety team and reliance on this is key to a successful airport fire design. In the absence of such competence, far less reliance on management must occur.
Airports operate on a continual basis (24/7) and are a critical piece of infrastructure. Therefore, large-scale evacuations or disruption of passenger processing in a terminal could be catastrophic for the airlines and the terminal operator for commercial and reputational (brand) reasons. Business continuity goals should be established in the QDR alongside life safety and property protection objectives and the on-going design development should consider these requirements as detailed in the airport fire strategy.
It is encouraging to see that the Middle East is positively embracing international best practice within the aviation sector to ensure a safe, secure and enjoyable customer experience throughout its airports. This aligns with the vision to be an international hub for business growth and development.