Design Guidelines for Truck Lanes on Mexican Two-Lane Roads

Abstract

The results of a research project undertaken by the Mexican Transport Institute and the Freight Transportation and Distribution Systems Department of the Autonomous University of Querétaro for generating design recommendations in adding lanes for trucks on Mexican two-lane, two-way roads are presented. Implementation of additional lanes traditionally has been considered among the most efficient low-cost improvements on specific grades (longer than 800 m and steeper than 3 percent). This paper discusses the problem of improving traffic operations on composite grades (a series of consecutive grades with different gradients) that are located in rolling or mountainous terrain by implementing added lanes in both directions. This can be done in a series of appropriate subsegments. Basically, these subsegments are in places that lack the necessary passing sight distance. The longest traffic platoons usually occur in these places.