Metodologia para avaliação dos fatores condicionantes da velocidade em regime livre em ambiente periurbano

Abstract

This paper presents a new methodology for the evaluation of the effects of posted speed limit, geometric and environmental characteristics on free-flow speed in transition zones, through a macroscopic analysis. A vehicle travels under free-flow conditions if its chosen speed is not affected by the presence of the vehicle ahead. In this sense, the free-flow speed reflects the driver's response to road geometric and environmental characteristics. In the first stage of the proposed methodology, new macroscopic variables reflecting the characteristics of transition zones are created through the use of multivariate data analysis techniques, namely analysis of clusters and principal component analysis. In the second stage, a regression analysis is performed in order to compare the effects of different variables on the adopted free-flow speed. This methodology is then tested for a set of 27 sites located in Portuguese two-lane highways, where drivers' speed, the existence of posted speed limit and some geometric and environmental microscopic characteristics were collected.