Vehicle lane discrimination in an electronic toll collection system

A vehicle position determination system for determining the position of a moving vehicle in a multi-lane roadway. Two or more roadway antennas each periodically transmit an identifier that is associated with and unique to the antenna to a transponder located in the moving vehicle. As the moving vehicle passes through the coverage zone of the antennas, the transponder counts the number of times that it receives each unique identifier and reports this information to a roadside controller. Based on this information, the roadside controller can determine a probable location of the moving vehicle. The vehicle location information can be provided to an imaging system to discriminate between transponder and non-transponder equipped vehicles.