Urban streets present many challenges for researchers attempting to collect traffic speeds without alerting the subjects. Drivers may adjust their speeds if they perceive it is being measured or recorded. This paper briefly explores the problems of measurement bias in speed surveys, indicates the unique demands of local street speed measurements and defines a suite of requirements for an unobtrusive speed measurement system capable of satisfying the demands of two ARRB Transport Research projects concerned with urban speed behaviour. However, it is recognised that such a device may find broader application. A review of research and product literature indicated that no commercial speed measurement systems were available that satisfied the system requirements and consequently, an inhouse development was pursued. The result is the StreetSpeed system, an unobtrusive, portable and affordable speed measurement system designed for operation on urban local streets. It utilises three sensor technologies, a K band radar, CCTV video and specially developed optical sensors configured as an `optical amphometer'. Using all sensors, the StreetSpeed system can provide speed profiles, spot speedy directional count and visual classifications. (A)
Samenvatting