20 Dec Ensuring safety and connectivity
2020 will see the realisation of the UAE’s ambition to hold and deliver a world class event showcasing it’s culture, history and future aspirations – Expo 2020. With multiple infrastructure projects improving the connectivity across the region and future projects coming on-line, it re-affirms the ambitions of the Middle East to connect the worldwide community. The Dubai Metro Extension and the Dubai International Airport projects are key for the success of the Expo 2020 writes Peter Stephenson, Business Development Manager, Warringtonfire.
In total there are 1,552 active transport projects in the GCC estimated at USD 377.6 billion. The GCC’s transport sector constitutes 6% of all active projects in the region and in dollar terms, these projects account for 15% of the total estimated value. There are 310 projects that are currently in the pipeline (concept and design stage) estimated at USD 125.6 billion. A total of 309 projects worth an aggregate value of USD 14.8 billion are in tender stage and 12 transport projects with a combined estimated value of USD 3.7 billion moved to construction from other stages during August 2019.
The fire engineer
The fire engineer is a key member of the airport design team providing expert advice for both operational and design solutions. Key to the project success is the fire engineer’s integration with the other design team members and stakeholders. With airport operational requirements and the architectural aspirations of the project, close communication with the airport operator, their fire safety management team, as well as the architect and other project disciplines, from the very conceptual stages, have proven to be fundamental to the successful design and implementation of an airport terminal fire safety design.
The fire engineer plays a key role throughout the design process, quantifying the agreed fire safety principles and being part of the project specification stage through to construction and design compliance on-site. For airports (like many other complex buildings), a robust strategy for commissioning the fire and life safety systems and inspecting the key elements for completeness, as well as participating in the training and handover of a functioning fire strategy, is becoming a key area of the fire engineer’s role.
Fire safety objectives & acceptance criteria
Connecting the world’s infrastructure to bring people together across multiple continents poses many challenges for both designers and facility operators. The safety of domestic and international travellers is a key objective for the success not only of the Expo 2020 but also all future sporting and cultural events across the region.
Fire safety challenges can be found in large mass transportation buildings, such as airports and railway/metro stations, however there are few building types that require proven operational support systems to enable the building to function (retail, security, customs, baggage handling etc.) whilst safely ensuring a positive customer experience. To ensure an optimum design solution can be achieved that satisfies the client’s aspirations, and also the Civil Defence, requires a robust fire strategy which, in many cases, will follow performance based fire engineering techniques whilst considering compliance with local and international codes. Key architectural aspirations to optimise this customer experience encourages large open spaces for the public areas and efficient operational design for back-of-house areas.
To achieve these goals the development of a fire strategy requires consultation and input from all members of a design team and all relevant stakeholders. This is an important consideration at mass transportation facilities, such as airports, as once on the airside (i.e. departures) side of the terminal, a passenger or object (such as luggage) will have 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 an x-ray/security equipment. The position of this demarcation line needs to be understood, as it needs full consideration when developing the evacuation strategy, including the provision of directional escape signage and zoning of fire safety systems.
Changai Airport in Singapore is a good example where the security clearance takes place airside of immigration clearance at the relevant flight gate and passengers from both arrivals and departures are free to mix in a common area prior to security clearance. The new Jewel and associated shopping area attracts passengers to enjoy a fuller experience before travelling to their final destination and incorporates the Changai Airport Skytrain which is an automated people mover connecting Terminals 1, 2 & 3.
Fire fighting access arrangements
When considering the access arrangements for responding fire departments it is important to consider a single control point to receive a briefing from airport staff on their arrival at an incident to ensure that a thorough assessment has been carried out prior to implementing a 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 by which they cross the airside/landside line is, therefore, an important consideration.
For all large and complex buildings 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 command centre will be separated from the remainder of the building by fire resisting construction and should have a dedicated access route direct to open air.
Typically an 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 building 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. Another
key consideration for the operators is to ensure the travellers have an uninterrupted travel experience and can fully utilise the airport facilities including duty free and shopping outlets – a key source of revenue. An understanding of this behaviour (particularly family groups) should be a key to a successful evacuation strategy.
With a focus on their process 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.
Fire strategy and fire engineering process
As previously mentioned, airport and/or railway project designs 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 (Application of Fire Safety Engineering to the Design of Buildings) 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 parametres 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 qualitative design review
The main stages in the QDR process identified in BS 7974 include the following:
a. Review of architectural design and occupant characteristics
b. Establish fire safety objectives
c. Identify fire hazards and possible consequences
d. Establish trial fire safety designs
e. Identify acceptance criteria and methods of analysis
f. Establish fire scenarios for analysis
The team formulated to carry out this process should be led by the project fire engineer(s) and is key to the success of the final fire safety design. The QDR Team should include representatives from the following areas:
- Client – including members of the security, retail, customs teams as they will have a fuller understanding of the operational requirements of the airport to be considered during the design
- Architect who will understand the architectural aspirations of the client
- Engineering Teams including mechanical, electrical and plumbing, transportation, landscaping etc.
- Airport Fire Department for input into operational response and access requirements including water supplies for firefighting (particularly airside operations)
- Civil Defence as AHJ and responder to emergency incidents (particularly landside operations)
- Contractor (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 the following be areas should be considered in relation to the architectural design and occupant characteristics of the building:
- building structure and layout, use(s) and contents of the building
- fire service access to the building
- ventilation systems
- unusual fire hazards
- planning constraints and
- client requirements, including possible future options
The passenger experience and interaction from first to last impression of the transportation hub 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 minimise 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 airport fire load 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 stream for the terminal operators. Unrealistic fuel loads and controls contained within a fire strategy will 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.
Basis of design
The input from the fire engineer during the design phase will be captured in the fire strategy for the building and should form the basis for any future works carried out in the relevant building. The initial design and construction phase will form only a small percentage of the buildings complete lifecycle with the operational period being the largest portion. Any changes to the building should be captured in the fire strategy and this should also include changes to operational procedures that could impact on fire safety. It is important that the fire strategy is kept as a `live’ document to ensure on-going safety is maintained.