Vehicle operating speeds in southwestern Colombia: An important database for the future implementation of optimization models for geometric design of roads in mountain topography

The essential objective of a road is framed in allowing the circulation of vehicles from a point of origin to a destination, being essential to fulfil completely this function, consider aspects such as: functionality, safety, economy, comfort, environmental integration and harmony or aesthetics. For this effect, a geometric design based on consistency must be achieved, which arranges the elements of the road and their geometric characteristics, helping to minimize adverse effects on the driver's expectations, perceiving homogeneity on the route, without abrupt variation in the level of attention necessary and thus be able to adapt to the changing geometric conditions of the road. In order to assess the consistency in the geometric design, different criteria and methodologies strongly related to the level of accident rates have been developed, which in turn are based on the analysis of the evolutions of the operating speeds. By virtue of the above, speed is therefore of vital importance to carry out any type of evaluation or analysis of traffic, since it is an important indicator of the quality of the service offered to users, because of it is function of the physical characteristics of the road and its environment. Among the main characteristics of vehicular traffic that can be studied from speed data, we have: the intensity of circulation, vehicle speeds and travel time, origin and destination of trips, vehicular accidents, among others. The purpose of this document is to present a database of speed obtained on a road located in the Pasto (Nariño department) in southwestern Colombia. The analysed road sector has a total length of 27.5 km and is developed in a predominantly mountainous topography. The data collected corresponds to the geometric characteristics of the road, as well as the design, traffic and operating speeds of each element throughout the sector. The data series corresponds to 312 elements of the geometric design, which are located continuously along sector. The design and road speed for each element, was determined from the geometric characteristics of the road; meanwhile, the operating speed was determined using spot speed data, which was obtained from field measurements with the Bushnell Radar Gun. For the determination of the Operating Speed in each element of the layout and for each class of vehicle considered (cars, buses and two-axle trucks), in each direction of movement, a minimum sample size of 64 Spot Speed data was used. The speed dataset is of great importance, because it provides traffic and transport engineering with relevant information for investigations such as: analysis of traffic accidents, establishment of design elements, traffic operation plans, regulation and control, zones with speed problems, study of traffic flows and finally, the assignment of design speeds for similar and future projects.