Guidelines for selecting roadway cross-sections in developing urban/suburban areas

This research attempted to develop guidelines for selecting appropriate cross-sections for arterial highways in developing urban and/or suburban areas. The two major features of cross-section considered in this research were the non-traversable median in the form of a raised or a depressed (grass) median, and the traversable median in the form of a two-way left-turn lane (TWLTL). Models for predicting accident rates and delay were identified from previous research for use in the selection process. Engineers of different State DOTs were contacted for their opinion on the topic. Real-life case studies were prepared to see how practicing engineers deal with them. A comparison of the results of the models and the views of the engineers was carried out. The results of all analyses revealed certain inconsistencies as well as some interesting patterns. It was concluded that accurate guidelines were difficult to formulate based on accident and delay criteria only. Land use was identified as a significant parameter in determining the choice of a cross-section. A stepwise procedure was developed to assist highway engineers in making a choice between a median and a TWLTL.