A comprehensive approach for the appraisal of the barrier effect of roads on pedestrians

Roads can become physical and/or psychological barriers to the movement of pedestrians, an impact known as the “barrier effect” or “community severance”. This paper proposes a new approach for measuring and valuing the barrier effect of different types of roads and for integrating the values into the appraisal of transport projects. This approach was developed based on the results of a survey of residents in areas around busy roads in two English cities. A series of stated preference exercises elicited preferences regarding crossing roads with specified design and traffic characteristics in locations with or without designated crossing facilities and making trade-offs with walking time and benefits or costs. The exercises were customised to represent different trip purposes (work, shopping, or leisure). Results were scaled with those obtained from a revealed preference exercise among some of the same participants, who indicated on a map their usual walking routes to locations that required them to cross the road. The results of the models of the participants' choices were then used to develop an index of the size of the barrier effect caused by the different characteristics of roads (number of lanes, presence/width of central reservation (median strip), traffic density, and traffic speed) and pedestrian crossing facilities (type, waiting time, and walking time to access them). The index was also related with the estimated willingness to pay to reduce the barrier effect for existing trips, and with the number of new walking trips that could be generated with that reduction.