Modelling effects of stair width on rates of stair climbing in a train station
Introduction
Accumulation of stair climbing can contribute to increased energy expenditure during daily living. Importantly, prompting pedestrians to choose the stairs over the escalator is a consistently effective intervention (Eves and Webb, 2006, Eves, 2007). Nonetheless, successful prompting requires a willingness by pedestrians to improve their health; those not considering any change in their behaviour, i.e. pre-contemplators, rarely report even seeing the prompt (Kerr et al., 2000). Additionally, effects of prompts are reduced over time (Kerr et al., 2001a), analogous to the return to less healthy behaviour that undermines individual approaches to behaviour change (Dishman, 1988). In contrast, changes to the built environment that promote active travel, unlike interventions that require healthy intentions, may produce permanent changes in behaviour (Sallis et al., 2004).
Studies of stair climbing on public access staircases consistently demonstrate increasing stair use as pedestrian traffic rises (e.g. Kerr et al., 2001a, Kerr et al., 2001b, Kerr et al., 2001c, Webb and Eves, 2007). When access to the escalator is blocked at high traffic volumes, some pedestrians choose the stairs as the faster route to their destination (Kerr et al., 2000, Kerr et al., 2001b). For stations, pedestrian flow is pulsatile with intermittently high rates of traffic as each train disgorges its contents. This simultaneous exit of passengers elevates rates of stair climbing (19.2%: Eves et al., submitted for publication) compared to shopping malls where traffic is spread more evenly (5.5%: Eves and Webb, 2006).
Fig. 1 depicts the percentage stair climbing for different numbers leaving trains between 8.15 and 9.45 am at Snow Hill station, Birmingham, UK in 2006–2007 (total n = 82,347: Eves et al., submitted for publication; Olander et al., in press).
As can be seen, a negatively accelerated function reaches a relative plateau at about 45% for more than 200 passengers. This plateau reflects saturation of the stairs and escalators such that both exit routes reach maximum capacity. The plateau's location is a function of the capacity of the stairs to remove passengers from the station, with contributions from speed of transit and stair width. For escalators, the speed of ascent is a fixed value whereas the speed of stair ascent is individually chosen. The second variable, width of each method of ascent, determines the maximum number of pedestrians on each step of the stairs and escalator. Thus rates of transport of passengers out of the station are a function of the average speed and width of each method of egress. Wider stairs have already been linked to greater stair use in buildings (Nicoll, 2007). This paper uses transport rates for passengers leaving a station to model the effects of an increase in stair width on stair climbing during the rush hour.
Section snippets
Methods
Observations (n = 5848) were made 8.00–10.00 am on three weekdays at Snow Hill station, Birmingham, UK in 2007. At 1.94 m, the stairs were wider than the escalator (1.24 m), with three passengers step− 1 on the stairs compared to two on the escalator. Two inconspicuous observers positioned near the bottom of the stairs and escalator counted the number of passengers using each method of ascent and timed the total duration of the ascent from the first passenger stepping on the bottom step until the
Observed transport rates for the escalator and stairs
Fig. 2 depicts the passengers s− 1 on the escalator and stairs plotted against the number of passengers leaving each train. Escalator transport rates were higher (mean = 0.90 ± 0.33 passengers s− 1) than the stairs (mean = 0.58 ± 0.24 passengers s− 1; t38 = 12.56 p < .001) consistent with reports of escalator choice as a faster option (see Kerr et al., 2001c).
For the escalator, multiple regression with linear and quadratic components fitted the data well (R2 = 0.921 p <.001), with transport rate described by the
Discussion
The predicted stair use based on transport rate (40.1%), while close to the observed value (45%), nonetheless underestimated it. Stair climbing was more prevalent than predicted by transport rate alone. As noted earlier, stair climbing rates in shopping malls where pedestrian traffic has less effect are 5.5% (Eves and Webb, 2006), suggesting some pedestrians may choose the stairs at most opportunities. Thus effects of transport rate, coupled with a preference for stairs in a minority, would
Conclusions
Commuters try to leave stations by the quickest route. Increases in stair width could harness this rush to work in the fight against obesity. Changes to stair width would have permanent effects on lifestyle physical activity, maximally being almost three times those achievable with health promotion messages for a doubling of width.
References (11)
- et al.
Worksite interventions to increase stair climbing; reasons for caution
Prev. Med.
(2006) - et al.
Six-month observational study of prompted stair climbing
Prev. Med.
(2001) - et al.
Active transportation and physical activity: opportunities for collaboration on transportation and public health
Trans. Res. Part A
(2004) Exercise Adherence: Its Impact on Public Health
(1988)All choices are not equal; effects of context on point-of-choice prompts for stair climbing
Obes. Rev.
(2007)