engleski

Analysis of sight distance at an at-grade intersection

Maneuvering distance and stopping sight distance are important traffic safety elements at an at-grade intersection. Croatian official standard for sight distance calculation (HRN.U.C4.050) dates from 1990. This regulation treats sight distance values in a very simplified way. The mentioned regulation seems to be outdated since various researches of real traffic conditions at an at-grade intersection have been conducted to detect significant factors influencing sight distance. In this paper an overview of sight distance calculation methods according to Croatian official standard (HRN.U.C4.050), and additionally according to Croatian guidelines for urban intersection design from the traffic safety aspect (Hrvatske ceste, 2004.), American guidelines for geometric design of highways and streets – The Greenbook (AASHTO, 2001.) and PIARC Road Safety Manual (2003.) is done. These calculation methods were applied at an at-grade intersection in City of Rijeka, where necessary calculation parameters (vehicle speed, friction coefficient) were collected at the site. This intersection is distinctive for greater amount of traffic accidents due to lack of maneuvering and stopping sight distance. The conducted analysis of different sight distance calculation methods shows that inspected calculation methods differ for calculation parameters and consequently given sight distance values. The sight distances obtained with suggested calculations from Croatian standard are in all cases less conservative than the sight distances calculated with other, more detailed methods. This is why a revision of current Croatian regulations concerning sight distance is suggested.

sight distance ; at-grade intersection ; calculation models

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