Operating speed models for two-lane rural highways

Drivers adapt their driving to the conditions that they find. When the design corresponds to what a driver hopes to find, the route is consistent. This diminishes the likelihood of drivers making errors and carrying out uncertain manoeuvres. Most evaluations of highway geometric design consistency are based on the analysis of vehicles' speeds. This study reviewed the main models of operating speed prediction on two-lane rural highways. Models calibrated in several countries have been compared by means of their application to the study of nine highway sections located in different terrain types. Also, field measurements have been included in the comparison. The research results show the strengths and weaknesses of those models, their similarities, differences and the lack of suitability of some of them for mountainous highways. Based on them, specific recommendations about which models would be suitable for use are included. The speed profiles predicted by the Spanish model show, in general, higher values than most models calibrated in other countries.