Dilemma zone protection ideally requires the exact position and speed of all the vehicles approaching the intersection. However, point detectors, typically used to protect vehicle incursion into the dilemma zone, only provide binary information about the presence or absence of a vehicle at a fixed point in space. The information regarding position and speed of the vehicle in subsequent time steps is extrapolated. The extrapolation error increases with the increase in projection time. Wide area detector (WAD) overcomes this drawback by tracking each vehicle at all times until they move out of range. Such a detector has the potential to improve the efficiency and safety of performance of dilemma zone protection systems. This paper develops performance measures for evaluating WAD. The performance of a WAD was evaluated at a heavily instrumented intersection in Noblesville, Indiana.