Wheeled Mobility Use on Accessible Fixed-Route Transit: A Field Study in Environmental Docility

Abstract

Multiple field studies provide qualitative accounts of usability barriers experienced by users of wheeled mobility devices on public transit. This study aimed to examine these usability barriers from the theoretical perspective of Environmental Docility by quantifying the relationship between functional capabilities of wheeled mobility device users and ingress-egress performance on accessible fixed-route transit vehicles in an urban setting. Twenty-eight wheeled mobility users each completed three trips on a predetermined route through the local public transit system. Ingress and egress times, user-reported usability ratings and open-ended comments were analyzed. Regression analyses indicated significant interactions between age and minimum parallel-park length on ingress and egress times. Specifically, lower functional capability reflected in older age and less maneuvering ability predicted decreased performance (longer ingress-egress times), indicating less adaptability to environmental demands and agreement with the Environmental Docility Hypothesis. Usability ratings and comments revealed difficulty with negotiating access ramps and turning maneuvers in the vehicle interior and in proximity to other passengers. Despite compliance with accessibility standards, current design of transit vehicles present substantial usability barriers for wheeled mobility users. Environmental Docility provides a theoretical basis to identifying modifiable factors related to person and environment for improving usability of public transit for people aging and/or with mobility impairments.

Keywords: accessibility; environmental docility; public transit; usability; wheeled mobility.

Figure 1

Plan view of interior configuration of the low-floor bus used in the study. The grey rectangles indicate the wheelchair access ramp at the front door for ingress–egress, and two forward-facing wheeled mobility securement areas in the bus interior.

Figure 2

Images depicting a wheeled mobility device user at the three bus stops used in the study (a) Stop 1 at the start of Trip-1 and end of Trip-3, (b) Stop 2 used between Trips 1 and 2, and (c) Stop 3 used between Trips 2 and 3.

Figure 3

Box-plots of tasks times (seconds) for ingress, mobility device securement attachment and removal, and egress, averaged across 3 bus trips per participant and stratified by user group: mid-wheel (n = 6) and front-wheel (n = 11) drive powered wheelchair users (PWU), manual wheelchair users (MWU; n = 6), and scooter users (SU; n = 5). Dots indicate statistical outliers (i.e., values greater than 1.5 times the inter-quartile range).

Figure 4

Interaction plots showing the effects of standardized parallel park length on predicted ingress (left panel) and egress (right panel) times at three values of standardized age: −1 SD (younger), 0 (average), and +1 SD (older). Error bands for each regression line represent 90% confidence intervals.

Figure 5

Medians (■) and 90% confidence intervals for task difficulty ratings (−3 = very difficult, 3 = very easy) and accessibility ratings (−3 = very unacceptable, 3 = very acceptable) averaged across 3 bus trips per participant and stratified by user group: mid-wheel (n = 6) and front-wheel (n = 11) drive powered wheelchair users (PWU), manual wheelchair users (MWU; n = 6), and scooter users (SU; n = 5).