Trial Evacuation Organisation and Process

Letters were sent to the building owners outlining the research project and the extent of our participation in and observation of their next trial evacuation. A copy of this letter and the formal agreement is included in the Appendix A3 along with the details of how the Data Protection issues were to be dealt with. Ethics approval was also obtained from the University Ethics Committee prior to the conduct of any of the trial evacuations and focus group exercises.

In order for the study to reflect actual practice the procedures did not permit any form of alteration to the evacuation strategy, plan or management. An example of this may be found in the procedures for the stair descent observers where the observer is strongly advised not to interfere with warden procedures or evacuee behaviour. They were merely required to observe and record events during each drill.

Once the contract or agreement had been signed the date for the exercise was agreed and the researcher was permitted to enter the building and carry out the following tasks:

• Measure up the stairs in accordance with the standardised template (see Appendix A3)

• Meet the emergency response team for the building including the fire wardens, explain the programme to them and supply them with a copy of the questionnaire and make the necessary arrangements to hand them out to their colleagues after the completions of the exercise.

• Obtain permission for the placement of the cameras and also access the day before the exercise to fix them in position.

• Obtain a copy of the building evacuation plan and become familiar with the requirements.

• Agree a time with the chief warden for the observation team to gather in the ground floor lobby on the day of the drill.

On the day of the drill with all the cameras fixed in position, the observation team fully briefed, all their watches fully synchronised and their floors/ stairs assigned the observers proceeded to their floors ten minutes prior to the sounding of the evacuation alarm. The cameras were all switched on during this ten minute interval so that they were recording. The observation team were all in position five minutes prior to the alarm sounding and after having notified the floor warden that they were ready and in position. The observer also recorded a reference time on the Dictaphone.

The evacuation alarm then sounded and in accordance with their procedures the observers with their Dictaphones switch on began describing the activities on the floor. As the occupants started to enter the stairs their flow across the entry to the stairs was recorded using a simple procedure. The Dictaphone recording acted as the time scale for analysis of the descent after the trial evacuation. The observer entered the stairs as part of the last group and proceeded to descend the stairs recording on each level;

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• The number of people in front of them on the flight

• Their distribution on that flight of stairs

• The number of people in front using the handrail

• Instance at which the observer placed their foot on the main landing at each level together with the number of that level.

• Other observations about other floors entering, mixing on those levels and the resultant delays

• Instances when the rate of descent slowed down or even stopped.

As each observer reached ground level they identified themselves on the last camera with their floor number, recorded the point at which they passed through the final exit and kept going until they were well clear of the building. They were required then to provide a further reference time, add any other observations they thought would be interesting.

After the exercise the team proceeded to remove the cameras (see Figure 3-17 for fixing detail) and cassettes from the cameras. Electronic sound files were created from the tapes and folders made with the data cards from each of the cameras. All of these were placed in a master folder for each trial evacuation exercise (Buildings M1-M6). These folders therefore contained the raw data for the reconstruction of the exercise using Excel.

Figure 3-17: Typical fixing and mounting for video cameras and camcorders in PDSA Cycles 2 and 3.

(Tape was used in PSDA Cycle 1 and failed in Building M2 because of the heat – 450_C+)

The questionnaires were gathered up from the fire wardens the day after the evacuation exercise and coded using standard variable names representing the questions. A copy of this coding schedule may be found in Appendix A3. The data was then transferred on to an Excel spread sheet and then transferred into the SPSS V16 files ready for analysis.

This procedure was repeated for each of the buildings M1-M6. Summary descriptions of each trial evacuation exercise may be found in Chapter 4 and the reconstruction of the drill together with the observation schedules may be found in Appendix A7.6. Copies of the raw data are also available for further analysis in electronic folders attached to Appendix A7.

The method of data collection for the trial evacuations could be challenged by other egress researchers such as Averill (Averill et al, 2005) in the lack of automation used in the gathering of data to more accurately determine speed. Averill (Averill et al, 2005) used a combination of Radio Frequency Descent Devices (RFID’s) and video cameras. The two systems could be

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interfaced. The author is required to defend his method and list the following reasons:

• It requires the placement of strategically located UHF devices.

• Electronic tags must be fitted to each occupant requiring a large number of tags per building and the risk of the tags not being returned. This was also seen as being extremely invasive by some of the building owners.

• The increased amount of interface between the various devices.

• Set up time available at each site.

• The overall cost was beyond the resources available to the author as he financed the entire study himself.

• The method used was in direct line with the 1980 study and the use of observers descending with the occupants provided a richness of data that would not have been available.

The letters of application and approval are located in Appendix A3 and can be used to substantiate the above especially in terms of the requirements for the observation team to be unobtrusive.

The other criticism would be the measurement of distance traversed from video footage. Normally The RFID’s would most likely permit automatic measurement of the distance. The distance in the 2008-2010 trial evacuation studies was measured using measurements provided by the regime set out in Figure 3-19 where all horizontal and raking measurements were recorded separately. Key points on the video images were selected so that the distance could be calculated using information from Figure 3-19. This is considered to be satisfactory especially when the data is being triangulated with survey response data.