Inter-step Variations of Stairways and Associations of High-Contrast Striping and Fall-related Event Observations

Abstract

Background: Variability in the riser and depth of each step in a stairway can decrease step predictability, and increase users fall risk. Unfortunately, inconsistencies in inter-step riser height and depth are common, but their impact may be lessened by adding high-contrast tread edges and vertical, monochrome striping applied to the bottom and top steps faces. Such contrast enhancement may draw greater attention to the steps edges or enhance the precision of the edges estimated location. Purpose: To determine if greater inconsistency in inter-step riser height and depth are associated with more frequent slips, trips, and falls, and if these events are reduced in flights of stairs with contrast-enhanced step edges. Methods: Stair users were videotaped on two public stairways. One stairway had black vinyl strips applied to the steps edges and black-and-white vertical stripes on the first and last steps faces. The intervention stairway was switched halfway through data collection. Stair users were coded for whether they experienced a fall-related event. A Monte Carlo simulation was used to determine the probability of observing a range of plausible distributions of fall-related events. Results: Flights of stairs with riser height variability of 14 mm and tread depth variability of 38 mm were associated with 80% of the observed fall-related events. 13 of 16 (81%) fall-related events occurred on the control stairway compared to 3 of 16 (19%) on the intervention stairway. The distribution of fall-related events observed between conditions had a probability of occurring by random chance of less than 0.04. Conclusion: These data suggest a vision-based strategy (i.e., striping) may counteract fall risk associated with inter-step riser height and depth inconsistencies. While the mechanisms of its action remain unclear, the high-contrast striping appears to reduce the incidence of fall-related events in the presence of inter-step riser height and depth inconsistencies.