Estimating Pedestrian Accident Exposure: Automated Pedestrian Counting Devices Report

Automated methods are commonly used to count motorized vehicles, but are not frequently used to count pedestrians. This is because the automated technologies available to count pedestrians are not very developed, and their effectiveness has not been widely researched. Moreover, most automated methods are used primarily for the purpose of detecting, rather than counting, pedestrians (Dharmaraju et al., 2001; Noyce and Dharmaraju, 2002; Noyce et al., 2006). Automated pedestrian counting technologies are attractive because they have the potential to reduce the labor costs associated with manual methods, and to record pedestrian activity for long periods of time that are currently difficult to capture through traditional methods. Data input and storage may also be less time consuming than with manual methods. On the other hand, the capital costs of automated equipment may be high; specialized training may be required to operate it; and automated devices are generally not capable of collecting information on pedestrian characteristics and behavior. For these reasons, automated devices are not appropriate for all pedestrian data collection efforts. The choice between which method is more appropriate to collect pedestrian data must be based on the accuracy level desired, budget constraints, and data needs specifications. Automated Counting Technologies Much of the research on automated pedestrian tracking devices has focused on pedestrian detection, not pedestrian counting. Extensive reviews of pedestrian detection technologies were conducted by Noyce and Dharmaraju (2002) and by Chan et al. (2006). Technologies include piezoelectric sensors, acoustic, active and passive infrared, ultrasonic sensors, microwave radar, laser scanners, video imaging (computer vision). Of the technologies listed above, those most adaptable to the purpose of pedestrian counting are: infra-red beam counters; passive infrared counters; piezoelectric pads; laser scanners; and computer vision technology. None of these devices are widely used for the purpose of counting pedestrians outdoors, but all have some potential to be adapted for that purpose. This report describes each of these technologies in detail, and discusses some of the technical strengths and weaknesses of each method. It is important to be aware that technical limitations are only one consideration among many when choosing an appropriate counting device. The device “packaging,” such as the method and location of installation may be equally important. For example, the location and accessibility of the device may create liability issues or promote vandalism.