Introduction to Fire Safety Management
10.1.2 The time required for escape
As discussed in Chapter 9, evacuation can be seen as having four distinct phases:
Phase 1 – alert time from fi re initiation to detection/recognition
Phase 2 – pre-movement time taken by behavior that diverts an individual from the escape route/s
Phase 3 – travel time to physically get to an exit
Phase 4 – flow time, i.e. how long it takes for the occupants to move through the various stages of the escape route. Doorways are invariably the least efficient element with the longest flow time and restriction
on the route.
The evacuation time is totally dependent upon the occupants responding to the fi re evacuation warning. Once the occupants of a building have been warned of the danger of fi re, there is always a delay when a number of initial behaviors can occur before they begin to travel to the exits.
Whereas Approved Document B to the Building Regulations provides guidance on the calculation of flow rates for exit routes, the British Standards Published Document (PD7974 Part 6 2004) – Human factors: life safety strategies – Occupant evacuation, behavior and condition, provides detailed information relating tob phases 2 and 3 of evacuation, i.e. ‘pre-movement and travel time’.
When devising a fi re evacuation procedure it’s useful to consider these two phases of human
behavior. In addition, it is important to understand that there are interactions between pre-movement and travel behaviors for all individual occupants that also impaction the overall evacuation time.
Evacuation time has two phases:
1) Pre-movement time – the time between recognition and response. This is the time between when the occupants become aware of the emergency and when they begin to move towards the exits.
In many situations the longest part of the total evacuation time is taken up with this first phase. It is difficult quantify as it is dependent on the complexities of Human Behavior.
2) Travel time – the time required for the occupants to travel to a place of safety. BSI PD 7974-6:2004 p. 2
Pre-movement behaviors
Pre-movement behaviors comprise the recognition by an individual of a fi re emergency and their initial
Response to the situation they have perceived. Recognition that there is a high level of risk acts as a powerful incentive to respond by deciding to evacuate.
During the pre-movement phase occupants will be carrying out their normal activities at the same time as receiving and processing information about the developing emergency situation. In this phase the normal activity of occupants may be active or inactive.
Once the perception process has been completed individuals will make decisions about how they may respond to the information received. Depending upon the perception of risk, occupants of buildings will often embark on activities which do not involve movement
Phase 1 alert
Time from fire initiation to detection/recognition
Phase 3travel time
To physically get to an exit
Phase 4 flow time
Time taken to move through the various stages often escape route.
Phase 2pre-movement
Time taken by behavior that diverts an individual from the escape route(s)
Introduction to Fire Safety Management
10.1.2 The time required for escape
As discussed in Chapter 9, evacuation can be seen as having four distinct phases:
Phase 1 – alert time from fi re initiation to detection/recognition
Phase 2 – pre-movement time taken by behavior that diverts an individual from the escape route/s
Phase 3 – travel time to physically get to an exit
Phase 4 – flow time, i.e. how long it takes for the occupants to move through the various stages of the escape route. Doorways are invariably the least efficient element with the longest flow time and restriction
on the route.
The evacuation time is totally dependent upon the occupants responding to the fi re evacuation warning. Once the occupants of a building have been warned of the danger of fi re, there is always a delay when a number of initial behaviors can occur before they begin to travel to the exits.
Whereas Approved Document B to the Building Regulations provides guidance on the calculation of flow rates for exit routes, the British Standards Published Document (PD7974 Part 6 2004) – Human factors: life safety strategies – Occupant evacuation, behavior and condition, provides detailed information relating tob phases 2 and 3 of evacuation, i.e. ‘pre-movement and travel time’.
When devising a fi re evacuation procedure it’s useful to consider these two phases of human
behavior. In addition, it is important to understand that there are interactions between pre-movement and travel behaviors for all individual occupants that also impaction the overall evacuation time.
Evacuation time has two phases:
1) Pre-movement time – the time between recognition and response. This is the time between when the occupants become aware of the emergency and when they begin to move towards the exits.
In many situations the longest part of the total evacuation time is taken up with this first phase. It is difficult quantify as it is dependent on the complexities of Human Behavior.
2) Travel time – the time required for the occupants to travel to a place of safety. BSI PD 7974-6:2004 p. 2
Pre-movement behaviors
Pre-movement behaviors comprise the recognition by an individual of a fi re emergency and their initial
Response to the situation they have perceived. Recognition that there is a high level of risk acts as a powerful incentive to respond by deciding to evacuate.
During the pre-movement phase occupants will be carrying out their normal activities at the same time as receiving and processing information about the developing emergency situation. In this phase the normal activity of occupants may be active or inactive.
Once the perception process has been completed individuals will make decisions about how they may respond to the information received. Depending upon the perception of risk, occupants of buildings will often embark on activities which do not involve movement
Phase 1 alert
Time from fire initiation to detection/recognition
Phase 3travel time
To physically get to an exit
Phase 4 flow time
Time taken to move through the various stages often escape route.
Phase 2pre-movement
Time taken by behavior that diverts an individual from the escape route(s)
การแปล กรุณารอสักครู่..
