Modified coefficients of Passenger Car Equivalent on urban highways with heterogeneous traffic (Case Study of Tehran)

With increasing urbanization, transportation technology has progressed and developed economy. In addition, roads and highways, have made in an effort to balance road capacity and demand. Knowing the capacity of a road is necessary in the planning, design and operation of roads. For an accurate estimate of the roads capacity, passenger car equivalent coefficients, are essential to provide a mechanism through which the vehicles are converted into reference vehicles. This paper discusses about urban highways, such as Tehran, which is significantly high degree of heterogeneity, and based on collected data from 8 highway in Tehran, presents passenger car equivalent factors from four different existing methods. in the following, obtained passenger car equivalent factors are compared with each other and with factors that are currently used in different traffic studies of Tehran. Significant differences are observed among obtained passenger car equivalent factors from each method