The performance of urban intersections in Brazil

Urban intersections govern the capacity of the urban road transportation networks. In consequence, there has been a great concern on the prediction and optimization of their capacity and performance. Considerable research has been dedicated to the development and production of models and procedures for the determination of intersection capacity. A number of factors have been reported to affect such capacity, including, geometric features, traffic characteristics and method of traffic control. It has been demonstrated, for example, that saturation flow is a main factor in the capacity estimation of a signal controlled intersection. This study has been concerned with an analysis of the performance of the urban intersection capacity in Brazil. A review was undertaken on the procedures for the analysis of urban intersection performance and capacity. It included intersection functions, types of traffic control currently available, capacity, concepts and definitions. Special emphasis was given to signalized intersection capacity and the main parameters of saturation flow, lost times and passenger car units P.C.U.S. Subsequently data was collected, processed and analysed in six cities in Brazil. The objective was the development and production of models for the prediction of saturation flow, lost times and passenger car units P.C.U.s for local use. Such models were developed and compared with the results produced by other models currently employed in some countries. Conclusions have proved that Brazilian traffic characteristics are different from those elsewhere and therefore should be locally investigated. Recommended local values have been provided. (D82735)