Design consistency refers to the conformance of a highways geometry with driver expectancy. Techniques to evaluate the consistency of a design documented within this report include speed-profile model, alignment indices, speed distribution measures, and driver workload. The use of operating speed as a consistency tool requires the ability to accurately predict speeds as a function of the roadway geometry. In this research project, several efforts were undertaken to predict operating speed for different conditions such as on horizontal, vertical, and combined curves; on tangent sections using alignment indices; on grades using the TWOPAS model; and prior to or after a horizontal curve. The findings from the different efforts were incorporated into a speed-profile model. Alignment indices are quantitative measures of the general character of a roadway segments alignment. These potential indicators may identify a geometric inconsistency when there is a large increase in the magnitude of the alignment indices for a successive roadway segment or feature or when a high rate of change occurs over some roadway length. Speed distribution measures investigated included variance, standard deviation, coefficient of variation, and coefficient of skewness. Driver workload is a measure of the information processing demands imposed by the roadway geometry on a driver.
Evaluation of Design Consistency Methods for Two-Lane Rural Highways, Executive Summary
2000
59 pages
Report
No indication
English
Evaluation of Design Consistency of Two-Lane Rural Highways
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