Speed profile prediction model of rural roads in flat terrain in Costa Rica

For some time, a commonly used engineering practice has been to evaluate the influence of the geometric design of roads on road safety by analyzing geometric design consistency. When evaluating geometric design consistency, it is necessary to know the operating speed profiles of the road to be analyzed. To this end, a variety of models of operating speed profiles are used, which are designed for the specific conditions of a particular region or country. For any analysis of highway geometric design, it is important to have information related to the horizontal and vertical layout of the project, as well as to the operating speed of vehicles. However, one limitation, which is often a source of error, is determining the operating speed of the vehicles. The aim of this paper is to develop models for predicting vehicle operating speed in Costa Rica by considering the characteristics of the road geometric design and of the existing vehicles. The procedure followed in the model included a series of steps, including from the analysis of the roads in the region to the development of models for predicting the speed profiles, as well as its validation. For the first time, different models are proposed for rural national routes in flat terrain in Costa Rica. The study demonstrates that the proposed equations provide for lower estimations errors, if compared to international models