Friday, March 06, 2009: 03:58:56 PM

Safety

MOB CONTROL

Nirmita Mehrotra explains how buildings and high-rises can be constructed to enable effective crowd management

Crowd management begins with design decisions, governing internal layout and decoration. The culture of safety and prevention has been discussed as a subject specifically in terms of management of emergency situations like fires, earthquakes, etc. But in normal circumstances, management of collective behaviour of crowds for efficient functioning of an activity and operation of facilities is still an untouched subject. Crowd management should be an integral part in the operation of all facilities in residential as well as commercial areas.

The regulation of pedestrian movement has always been a challenge whether in malls, multiplexes, community halls or temples complexes during festivals. The recent statistics of chaos in festive gatherings as well as existing fire hazards in high-rise towers, reinforce the importance of creating self-awareness regarding the steps to be taken during emergency situations, instead of depending on the regulators. Crowd management aims to facilitate crowd gatherings to improve comfort and safety. Some of the potential hazards requiring identification and management control are listed below:

  • Reverse or cross flows of pedestrian traffic in a dense crowd
  • Flows that are obstructed by queues or gathering crowds
  • Large pedestrian flows mixing with animals or traffic
  • Moving attractions within a crowd like food vendors, which prevent the smooth flow of crowds


Common behavioural pattern

The study of crowd movement and crowd behaviour during an emergency is necessary not only for fire and building code officials but also for many other disciplines like architects and interior designers, facility managers, etc. They need to formulate a design layout for optimum distribution of facilities and functions throughout the available space and a number of exits for emergency planning. In almost all the cases, victims are injured or killed by the behaviour of the crowd rushing in a panic rather than the actual cause of the disaster. In the fire incident of the Indian Oil’s office complex in Noida, the crowd behaviour turned into self-destruction under panic.

  • Panic-stricken people do not recognise alternative exits in emergency situations and instead try to leave from the same way they entered, thereby causing chaos.
  • In very large buildings for assembly use, the hazard of crowd crushes can exceed that of fire or structural failure.
  • In case of a fire, dense smoke rapidly fills the room and obscures the view of the overhead exit signs above the doors, which causes the people to flee toward the main entrance.


Architecture and interior design

Crowd management begins with design decisions to induce smooth flow and regulate the circulation of pedestrian traffic. The internal layout should provide a defined path of circulation and smooth flow of people from the time they enter the building to the time they exit. Curves allow people to maintain their normal walking pace while giving them time on approach to areas where they have to make a path decision. The number of corners should be limited as corners force people to slow down and sometimes lead to indecision if one doesn’t know what options are available around the corner. Fewer options or alternate paths reduce confusion and thus lessen congestion.

A study of the Roman public buildings like Basilicas and amphitheatres dating back to the 6th century BC have revealed the incorporation of crowd management in their architectural design and building layouts. The configuration adopted at Pompeii Stadium is a true oval with oncourses  having no sharp turns. Pompeii Stadium has only six stairways and one general direction for ingress and egress. Once outside, entrances to the Palaestra are all on one side, and the main road does not split off to side roads until the crowd would be well-dispersed. Pedestrian circulation in the context of building exit and entrance doorways, turnstiles and other parts of the buildings have to be regulated to avoid crowd build up at a point. Building regulations, prescribe dimensions of movement for the various components like the length and width of corridors, stairs, ramps, the number of doors and their location to achieve an acceptable degree of safety.

After the fire incident in Meerut, it was made mandatory to get approvals from fire departments for installation of fairs and festive melas. It has been identified that crowd safety in public assembly places involves the study of architectural design for safe egress based on collective human behaviour. The National Building Codes (NBC) should review existing regulations concerning pedestrian and crowd processing in the changing pedestrian flow patterns with emphasis on, but not limited to, high density rates, ingress flows, ticket processing, entrance configurations, the influence of environmental variables and crowd dynamics in high-density situations. Queuing, ticket processing, crowd types and behaviour, turnstiles, environmental influences, aisle configurations and door and entrance dimensions are a few critical topics that need to be addressed.

Techniques for successful crowd management
A comprehensive crowd management plan should be formulated based on the study of crowd management techniques. Traffic volumes and a safety plan should be drafted by local facilities or property managers. A crowd management plan and an emergency plan should to be prepared in writing well ahead of the actual event.

Strategising traffic management plan:
The egress system is considered a passive component within the fire and life safety protection design, yet it is an active and integral part of the overall safety protection concept. Regulations are required for building access and emergency egress. The entrance designs intend to accommodate crowds based on data obtained from normal conditions and typical crowds.

Risk management:
Prevailing and probable risks need to be understood and incorporated in the emergency plan to prepare the facility for anticipated risks. Identifying and assessing the level of risk associated with the proposed activity is as important as exploring and investigating possibilities of what can go wrong and create an emergency situation. Monitoring and controlling risk, planning and developing procedures for dealing with routine emergencies is necessary from the safety point of view.

Emergency evacuation/egress planning:
It involves the problems and safety of crowds during emergency evacuation/egress, traffic flow plan and control plan. Evacuation planning for able-bodied and disabled people, areas of rescue assistance alarms and signage should ensure that exit routes are safe and in compliance with fire codes. Aisles and steps that are likely to be used as evacuation and escape routes need to be well lit or clearly marked. Floor plans should identify and clearly demarcate the location of exits, primary and secondary evacuation routes, accessible egress routes, areas of refuge, manual fire alarms, portable fire extinguishers, fire alarm and controls. All exits and an escape planning grid in the building should be well-marked on the escape plan with alternate stairways too, in case the main stairway is blocked by fire.

Management techniques:
There is a need to understand the distinction between crowd management and control. There has to be a clear understanding in the roles and responsibilities of facility managers, owners, event promoters, police forces and other private security services. Though experience and knowledge of the building is a must for all, proper utilisation of the existing communications systems and an appropriate ratio of management and other personnel to total attendees at a time is vital. Other management strategies include the following aspects.

  • Emergency management and preparedness: A manual should be formulated addressing the complete range of emergencies, power loss, fire, severe weather, earthquake, crowd incident and terrorism. The attendees need to be clearly informed of the situation.
  • Building management systems like route choices especially for vertical travel, resting and waiting areas and refuge areas need to be highlighted. Efficient signage gives a sense of orientation, route decision and destination recognition.
  • Fire protection system: Structural soundness, fire protection and prevention, compartmentalisation (dividing the building into fire safe units), automatic detection and suppression of fire, smoke control alarm and communications systems should be used effectively to avoid causalities.
  • Circulation systems: Merging of paths, branching points, route redundancies (alternate paths), counter flow, cross flow and queuing situations, control possibilities, including metering and flow capacity adequacy are some of the significant aspects.
  • Volunteers from the local community can work wonders with other facility representatives while observing crowd responses and crowd handling, doorways and vertical and horizontal exits. Managers should be trained to regulate evacuation in case certain exits are blocked due to emergencies.


While the role of the manager is to avoid a build-up of crowds, we as part of the crowd, can encourage a culture of safety being aware of at least the entrances and exits of any place one we are there.

References


The author is Practising Architect, Facility Manager and Urban Planner, Delhi. She can be contacted at
nirmita2006@gmail.com


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