Registration-plate surveys are an established technique in transport engineering for measuring a wide variety of traffic characteristics. For example, surveys can be used to determine routing patterns and trip times, origin&destination by noting the vehicle registration numbers at a range of key sites in the study area. Similarly, turning flows at intersections can be measured by noting the registration of vehicles that enter and leave the intersection.

In all but the lowest volume situations, it is simplest to read license numbers by manual method, for critical traffic flow videography method is used. The license plate numbers are being used for simple matching for origin-destination (O-D) study.

In the manual method,the observer should be stationed near the road as near as possible, at a point where the traffic is slow or stopping.Because of dirt and salt, the winter months are usually bad for collecting plate numbers, although an adequatesample may be taken. The observer should face oncoming traffic to read plates. Plate numbers are noted down into thespecific format. When an O-D Study is being conducted, beginning and end data collection times for variousobservers must be coordinated to account for thedistance between observers, the traffic already in the system andthe desired time interval.

In the videography methodvideo image processing system utilize machine vision technology to capture details about individual vehicles. The video footage is useful for number plate recognition and their classification, is collected manuallyin the office.