Differences in measurement methods for travel distance and area for estimates of occupant speed on stairs

Many previous studies have reported that the density in the stairs affects the achievable speed of the population using them. To measure the speed, one value that needs to be known is the distance. Similarly, to measure the density, one value that needs to be known is the area used by the population. Previous studies have used different methods to calculate these values and this paper reviews some of these different methods. Comparisons are made between these methods to show the difference in results that can result simply using data and equations developed using different assumptions. Then theoretical equations are developed for the travel distance and area based on how people have previously been observed traveling along arcs while crossing landings on stairs. Finally, the effects of misusing the different methods for calculating travel distance and area are compared using data from an actual building evacuation drill. It is shown that misusing methods can lead to significantly different results for the same data.

► We review studies using different methods to calculate travel distance and area. ► Comparisons show how these methods lead to different results if misapplied. ► We develop theoretical equations based on people traveling along arcs on landings. ► Actual data is used to show effects of different measurement methods. ► Misuse of equations for leads to significant differences in results.