Bangalore's much-awaited metro rail was flagged off on 20 October. Like its counterpart in Delhi, its swanky stations include modern facilities of safety at par with international standards. Venkatesh Ganapathy explains why metro trains and stations need to be aware of the limitations of codes and standards.
The overwhelming number of potential fire and security challenges that confront today's envirÂonment increasingly point out to the need for a well-planned strategy to successfully cope with the potÂential threats. This is something that needs to be on the drawing board of regulatory authorities.
The operational challenges in fighting fire result from a number of factors: the wherewithal available with fire brigades, the emergency response of people involved, the time within which fire brigade can arrive at a scene, means of egress, the fire protection equipment that can take care of fire till the fire brigade arrives etc. It is essential that evacuation plans must look at functional ways of evacuating a large number of people within a short time. Metro stations do present increased challÂenges due to their dense population and also heavy vehiÂcular traffic in adjoining areas.
Fire Safety in metro stations
After the Taegu subway fire incident in South Korea, fire prevention became an important consideration of the Mass Rapid Transit (MRT) system of Singapore. That MRT uses National Fire Protection Association (NFPA) guidelines for enhancing fire safety within metÂro systems. Ireland has its own standards for fire safÂety for the metro system. UK follows a combination of NFPA and British standards. In Bangkok, the MRT operates 19 three-car metro trains with two motor cars and a centre trailer car. Each train is provided with two fire extinguishers, while the driving cab has one.
In Australia, the safety assurance process is a risk-based process that covers all design aspects that affect safety, including signals, track design, occupational heaÂlth and safety, security (including terrorist risks) and fire protection engineering. Fire protection engineers can expect their fire strategies to be challenged in detail. Prescriptive codes may give some direction for fire straÂtegy, but reliance on these alone may not demonstrate that the required level of safety has been achieved.
Codes, standards and jurisdictions
Besides identifying the codes and standards, the praÂctising engineer must also identify the many authorities having jurisdictions and their role in the project. Examples of different authorities are the project owner, architect, insurance organisations, building officials, fire officials. Codes offer detailed guidelines for the deveÂlopment of structures. Standards provide the technical details necessary to meet code requirements.
Codes specify what and where, while standards say how. Standards contain requirements concerning the apÂplication design, installation and location of fire proÂtection systems or features required by the codes. The proÂduct and system standards should seamlessly merÂge to give a balanced protection. Where required, the design engiÂneer has to tweak the design to obtain this balance.
If individual smoke detectors have a sensitivity that is less than what is permitted by system standard, then the designer has to place the smoke detectors in close proximity (than the specification by system standard). This sort of design is labelled as a performance based design. All the components of a fire protection plan must work in perfect harmony with each other.
Fire protection engineering objectives
The fire protection engineering objectives include safeguarding people from injury due to a fire, avoiding fire spread to adjacent property and facilitating emerÂgency services' activities. A 'safety-by-design' approach is adopted for all design elements to include consideraÂtion to installation, operation and maintenance risk. Other objectives include operational continuity and reliÂability, which can involve maintaining operations after a relaÂtively small fire, maintaining operations in degraded mode after a significant fire, and implementing a process to avoid escalation of a fire. These operational objectives require early detection and response to incidents, inclÂuding a robust communication strategy:
- Fire initiation and development and control
- Smoke development and spread and control
- Fire spread and impact and control
- Fire detection, warning and suppression
- Occupant evacuation and control
- Fire brigade intervention.
Rail fire safety is part of a dynamic system. In a fire or other emergency, the number of passengers on a train, number of trains in a tunnel and initial response of the rail operator depend on the system operation. The best place for evacuation is the station, where there is the capacity for the safe, rapid evacuation of a train.
The resilience of other train systems can improve fire safety, for example:
- Fire rated floor to the passenger compartment, to proÂtect passengers from under car traction or brake fire;
- Two cars to have independent power connection via fire rated (or fire separated) cables to power transÂmission units;
- Multiple motor units, so that a train can continue to the next station, even with failure of one or two units.
These features are important in allowing a train to continue safely to the next station, even with a severe fire affecting one car.
Escape via the station
There are many factors that affect safe egress from stations, including smoke control and occupant behaviour. A key design issue is predicting the occupant load numbers in an emergency and acceptable evacuation times and NFPA 130 is used as a standard.
Delhi Metro as benchmark: I urge all the industries to look at Delhi Metro as a sort of a role model in the manner in which they have ingrained safety as an inteÂgral part of project management. When I contacted Punj Lloyd officials in Bangalore Metro, all that they said was: “We simply followed the Delhi Metro model.” Fire fighting system for the complex comprising of Hydrant, Hose Reels, Sprinklers and portable fire extiÂnguishers is based on NBC-2005. Their tender document is like a mini text book on fire safety. We can gauge that Delhi Metro has used a combination of NBC, IS staÂndards, NFPA standards and also the rules from Chief Fire officer for building a robust fire safety system, besides insisting on passive fire protection measures.
Not an option
The NFPA 101 Life Safety Code assumes greater proÂminence for metro stations due to the huge number of commuters in the railway stations at a given point of time. Fire protection for a metro station must be holiÂstic-besides the normal fire fighting equipment, the structural performance of the building must be attuned to requirements of fire safety.
Fire safety in metro stations is not limited to safety at the stations-it also includes safety in the trains. Those who apply the codes and standards have to use them as a tool, understand their limitations, know when to depart from them and when to supplement them. In a world where building construction technology is rapidly advÂancing, let us not allow codes and standards to give us a false sense of security.
The author is an academic and a Project Management expert.
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