Iso-Veloxic Traffic Sampled Jointly in Space and Time

As part of a continuing general investigation into the fundamental relations of traffic flow, the sampling properties of the variables speed, flow, and concentration of an ideal traffic stream, measured in rectangular space/time domains according to Edie's definitions, are evaluated and discussed. Although the speeds of drivers are independently distributed and maintained constant regardless of the proximity of other vehicles, it is shown that the speed and flow and the speed and concentration are both marginally correlated. Analytical expressions for the serial and cross-correlations of the flow and concentration in consecutive samples are given, and it is shown that the flow and concentration are distributed with both discrete and continuous probability components, with variance/mean ratios less than one.