Sight obstruction at at-grade pedestrian crossings: A review of the understanding of the meaning of zigzag lines

Parked and stopped vehicles in the vicinity of an at-grade pedestrian crossing obstruct visibility between pedestrians crossing the roadway and approaching vehicles, leading into vehicle-pedestrian crashes. Pavement zigzag line markings at at-grade pedestrian crossings, mostly at mid-block locations are used to restrict parking, stopping, and overtaking within the crossing, to enhance driver-pedestrian visibility. Yet, in some countries zigzag lines are used as advance markings to the crossing. Like any other traffic control device, zigzag lines' effectiveness hinges on road user's understanding of their meanings. This paper reviews the literature on the applications and understanding of these lines at pedestrian crossings. The meaning of zigzag line pavement markings at pedestrian crossings has not been well understood to some road users and road safety stakeholders worldwide. This dilemma may suggest that educating road users, especially drivers, may be necessary in order to improve pedestrian safety. Documented literature such as this one may also improve the understanding of these lines to road safety stakeholders. Despite of the importance of unobstructed sight between the pedestrian and the driver, treatments in the forms of signs and pavement markings require continuous education and enforcement. Practicing traffic engineers may want to place more emphasis on engineering treatments that are more effective in improving pedestrian safety, such as those that manages vehicle speeds, than relying heavily on traffic control devices that are often misunderstood and lesser effective such as zigzag lines.