Assessing the Impact of Turning Vehicles on Pedestrian Level of Service at Signalized Intersections

Abstract

The Highway Capacity Manual provides two methods, based on delay and space, for the assessment of pedestrian level of service (LOS) at signalized intersections. Current procedures for evaluating pedestrian LOS are examined, and results indicate that these procedures do not adequately reflect the negative impact of turning vehicles. Pedestrian LOS measures are proposed to reflect not only pedestrian delay and space but also traffic interruptions, freedom of movement, and comfort. These measures are consistent with LOS measures currently used for freeway segments and ramp merge areas. The percentage of compromised pedestrian crossings is proposed as a means to quantify the negative impact of turning vehicles on pedestrian service and as a LOS measure at signalized intersections. A pedestrian crossing is designated as compromised if a pedestrian is delayed or is forced to change travel path or speed in response to a turning vehicle. The percentage of compromised pedestrian crossings was assessed for 13 crosswalks. Results of the assessments illustrate that as right-turn volumes increase, the percentage of compromised pedestrian crossings increases. The proposed method provides an objective engineering tool for measuring the impact of turning vehicles on pedestrian service. It may be appropriate to use this measure to quantify the need for pedestrian improvements (e.g., if the percentage compromised exceeds 15%, then it may be appropriate to implement a leading pedestrian interval or other enhancement).