The effects of fatigue during deep metro evacuations and its implications on evacuation modelling tools

Abstract

The thesis purpose is to determine how people’s evacuation performance is affected by carrying weight while performing a stair-climbing motion. The fire safety engineering and physiology fields are merged to increase the knowledge regarding ascending evacuation. A laboratory experiment was conducted, in which participants performed three different sessions; during the first session, participants performed a sub-maximal test that would support the calculations for the prediction of the ideal step-rate estimating their VO2max by measuring their heart rate during a cardiovascular activity maintained approximately for 6 minutes; during sessions 2 and 3, participants performed a 5-minutes stair-climbing exercise, they did so under two modalities: 1) by not carrying an 8 kg backpack during one session, and 2) by carrying the 8 kg backpack during the remaining session. Measurements for oxygen uptake (VO2), heart rate (HR), and perceived exertion using the RPE Borg’s scale, where obtained during the stair-climbing experiment, and calculations for the energy expenditure (M) were then compared. A simple evacuation modelling case using the Mass-Motion software (MM) was conducted to obtain evacuation times; the model was configured in different manners, using 1) default parameters 2) walking speed distributions from available field experiments and 3) data from the current laboratory results. Using the findings during the laboratory experiment and considering people’s physiological aspects that can limit a stair-ascent motion during an evacuation, an additional scenario is described; this scenario includes a stair divided in 4 sections and separated by 3 resting planes, according with the average reduction-time requests by the participants during the “backpack” session.

Popular Abstract

Underground metro systems offer a transportation option to millions of users around the world, whom are constantly increasing over the years while higher population densities are expected as part of city expansions; in order to supply such demand, designers are opting to build deeper metro stations; for instance, in Kiev, the deepest metro station, Arsenalna, has a vertical drop of 105.5 m, meanwhile in Stockholm T-Sofia metro station is under construction and planned to have a 100 m depth. This kind of facilities are considered as deep metro stations and they represent several challenges in order to have a holistic design that includes comfort, functionality, and safety for the metro users.
Disregarding the metro stations high utilization, few studies can be found concerning the implications of fatigue during ascending evacuation, even when it is known that a stair-climbing exercise represents a challenge for metro users; therefore, keeping in mind this particular knowledge gap and by merging two science fields, fire safety engineering and ergonomics, this thesis purpose is to determine how people’s evacuation performance is affected by carrying weight (8 kg) while performing a stair-climbing exercise.
A laboratory experiment was conducted, in which participants performed three different experimental sessions. During the first session, participants performed a sub-maximal test that would support the calculations for the prediction of the ideal step-rate in which they would theoretically be able to complete a 5-minute stair-climbing exercise without reaching exhaustion; this was done by estimating their Maximum Oxygen Consumption (VO2) by measuring their heart rate during a cardiovascular activity maintained approximately for 6 minutes. During sessions 2 and 3, participants performed a 5-minutes stair-climbing exercise; the goal of theses sessions was to expose the participants to the same exercise but under two different conditions: 1) influenced by additional weight and 2) not influenced by additional weight.
Measurements for oxygen uptake (VO2), heart rate (HR), and perceived exertion using the RPE Borg’s scale, where obtained during the stair-climbing experiment, and calculations for the energy expenditure (M) were then compared. After completing the experimental phase, a simple evacuation modelling case was developed using Mass-Motion software (MM) as an example of evacuation modelling tool; the model used for the evacuation simulations was configured in different manners, using 1) default parameters 2) walking speed distributions from available field experiments, also taken as a benchmark case to compare results, and 3) data from the current laboratory results. Using the findings during the laboratory experiment and considering people’s physiological responses to stair-climbing exercises that can limit a stair-ascent motion during an evacuation, a hypothetical scenario was then described which intended to display how the evacuation times are affected when applying values that include the effect of fatigue, exhibiting the necessity to continue the research effort to include fatigue into evacuation modelling tools, to obtain simulation times that resemble more accurately a natural human response in emergencies.

• author: Velasco, Alejandra
• supervisor: Enrico Ronchi
• organization: Division of Fire Safety Engineering
• course: VBRM05 20181
• year: 2018
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: stair-ascent evacuation, stair evacuation modelling, stairs, physiology, fire safety engineering
• publication/series: LUTVDG/TVBB
• report number: 5572
• other publication id: LUTVDG/TVBB--5572--SE
• language: English
• id: 8951673
• date added to LUP: 2018-06-20 12:56:14
• date last changed: 2018-06-20 12:56:14