title: A relative access measure to identify barriers to efficient transit use by persons with visual impairments.
abstract: OBJECTIVE
  Persons with visual impairments or blindness can face significant restrictions to their efficient travel, especially when attempting transit transfers and using a large, multi-modal terminal. Little is known about what makes some tasks much harder than others. This paper presents an approach to empirically measure the difficulty of a variety of transit tasks.
  
  
  METHODS
  An experiment was conducted at an urban transit terminal, with three other transit modes nearby. Thirty persons with visual impairments attempted to make five simulated transfers between these modes. Errors and time to complete these tasks were collected in order to quantify the nature of various barriers to efficient travel for this group. In total, 20 locations were visited. Completion times were compared to a sighted traveler to determine a measure of the time penalty, or 'relative access measure.'
  
  
  RESULTS
  Two basic findings are reported. Empirical data showed that different types of transit tasks and locations had a wide range of difficulty and inherent time penalties. Some tasks like crossing a difficult street, finding unmarked track doors, and finding inconsistently placed amenities were quite time consuming and sometimes impossible to accomplish. Other tasks, like walking to a street corner and crossing a simpler street, had much lower penalties and could be completed with ease.
  
  
  CONCLUSIONS
  The placement of additional cues, those of identity and direction, provided with auditory signage, were able to eliminate much of the uncertainty and time restrictions associates with transit use and navigation for persons with visual impairments.
authors.affiliation: Department of Geography, University of California, Santa Barbara, CA 93106-4060, USA. marstonj@geog.ucsb.edu
authors.forename: James R
authors.initials: JR
authors.lastname: Marston
authors.forename: Richard L
authors.initials: RL
authors.lastname: Church
mesh_terms: D000328:Adult; D000368:Aged; D001107:Architectural Accessibility; D001766:Blindness / Q000503:physiopathology* / Q000534:rehabilitation; D006233:Persons with Disabilities / Q000534:rehabilitation*; D004526:Efficiency; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009949:Orientation; D013647:Task Performance and Analysis