Which environmental factors most strongly influence a street's appeal for bicycle transport among adults? A conjoint study using manipulated photographs.

BACKGROUND: Micro-environmental factors (specific features within a streetscape), instead of macro-environmental factors (urban planning features), are more feasible to modify in existing neighborhoods and thus more practical to target for environmental interventions. Because it is often not possible to change the whole micro-environment at once, the current study aims to determine which micro-environmental factors should get the priority to target in physical environmental interventions increasing bicycle transport. Additionally, interaction effects among micro-environmental factors on the street's appeal for bicycle transport will be determined.

METHODS: In total, 1950 middle-aged adults completed a web-based questionnaire consisting of a set of 12 randomly assigned choice tasks with manipulated photographs. Seven micro-environmental factors (type of cycle path, speed limit, speed bump, vegetation, evenness of the cycle path surface, general upkeep and traffic density) were manipulated in each photograph. Conjoint analysis was used to analyze the data.

RESULTS: Providing streets with a cycle path separated from motorized traffic seems to be the best strategy to increase the street's appeal for adults' bicycle transport. If this adjustment is not practically feasible, micro-environmental factors related to safety (i.e. speed limit, traffic density) may be more effective in promoting bicycle transport than micro-environmental factors related to comfort (i.e. evenness of the cycle path surface) or aesthetic (i.e. vegetation, general upkeep). On the other hand, when a more separated cycle path is already provided, micro-environmental factors related to comfort or aesthetic appeared to become more prominent.

CONCLUSIONS: Findings obtained from this research could provide advice to physical environmental interventions about which environmental factors should get priority to modify in different environmental situations.

TRIAL REGISTRATION: The study was approved by the Ethics Committee of the Ghent University Hospital.

TRIAL REGISTRATION: B670201318588. Registered at 04/10/2013. https://www.ugent.be/ge/nl/faculteit/raden/ec.