The estimation of passenger car equivalent for highway under oversaturated conditions

Depending on the characteristics of oversaturated traffic flow, the algorithm based on speed-density model is put forward to estimate the passenger car equivalent (PCE) in this paper. And the consistency of jam density is identified as the equivalent criterion. Utilize PCE to study the influences of various vehicles on oversaturated traffic flow. First of all, this new algorithm is established according to the `I-80´ field data provided by NGSIM. Then, the results directly prove the consistency of jam density and show that heavy vehicles have a larger effect on the oversaturated traffic flow than passenger cars. The speed-density algorithm can be used to estimate the PCE under oversaturated conditions and jam density keeps consistent when the road is crowded.