Visual complexity in highway work zones: an exploratory study

Abstract

Work zone safety is a priority of the transportation profession. One way to increase work zone safety is to identify the situations that threaten safety. This study was completed as an exploratory analysis of possible factors and combinations of factors that may contribute to visual complexity in a work zone and therefore cause difficulties in path-finding from a motorist's perspective. The objectives of this thesis were (1) use Critical Incident human factors techniques to identify sections of highway work zones that present path-finding difficulties for motorists; (2) use Positive Guidance techniques to identify and evaluate visual complexity features present in the problem sections of highway work zones as identified through the Critical Incident Technique; and (3) develop recommendations based on objectives one and two. Motorist drive-throughs were completed at nine sites in Texas. The results of these drive-throughs indicated that motorists' difficulties could be categorized into seven groups. These categories were (1) nighttime light sources; (2) exit/entrance ramp issues; (3) alignment differences between the roadway and parallel roadside features; (4) lane shift issues; (5) CMS issues; (6) inconsistencies in signing; (7) traffic control placement. Recommendations to improve the design of work zone traffic control plans and therefore decrease the visual complexity affecting motorists' path-finding were made.