Factors Influencing Lateral Distance and Speed of Motorized Vehicles Overtaking Bicycles

Abstract

This research analyzed the factors influencing lateral distance and speed of motorized vehicles overtaking cyclists. The measurement apparatus consisted of an instrumented bicycle equipped with an ultrasonic sensor, a speed radar, GPS devices and a GoPro camera. The experiment was carried out along a predetermined route in the urban area of Londrina, in the state of Parana, Brazil. A total of 36 tours were performed, wherein 2032 overtaking maneuvers were identified. Several factors were regressed on two dependent variables, namely the overtaking speed and the lateral distance, within a path analysis modeling framework to assess their contributions to the cyclist safety. The presence of painted bike lanes was shown to be the most important aspect, as lateral clearance increased by an average 31 cm compared with that for streets without this intervention. It should be noted though that this effect is higher for lanes with larger widths, with practically no influence on narrower lanes. Larger lateral distances were found in wider streets, whereas heavier vehicles and higher speed limits were associated with faster overtaking maneuvers. The most critical factor was related to cycling in commercial city zones where the combined effects posed a greater risk to cycling (i.e., higher overtaking speeds with shorter lateral distances). These findings shed light on relevant policies to promote cyclist safety and cycling attractiveness, such as expanding cycling infrastructure, decreasing street speed limits and informing citizens about the safest cycling routes in their urban environment.