Detection of faulty flow measurements based on queueing models and measured delays at intersections

Results of a case study for two signalized intersections in the Viennese intraurban road network have shown that detectors delivering artificially introduced faulty flow measurements can be detected. The method compares the theoretical delay distribution based on a deterministic queuing model to the empirical delay distribution of measured flow and speed values. A prerequisite is that the measurements at the intersection cover both under- and over-saturated traffic situations. The described method can detect several types of errors, namely overcount, undercount and Gaussian noise errors. The sensitivity of the method depends on the intensity of the error, i.e. relative error and standard deviation. As the method has achieved good results for artificially introduced errors, similar errors in real data will also be detected, since the investigated error types are typical for urban flow measurements.