Prediction models for space mean speed on urban roads

The research investigates the relationship between driving behavior and characteristics of the road environment in urban area. This study allows the identification of factors which influence driving speed. The purpose is to develop mathematical models which link driving behavior with infrastructure geometric characteristics. The parameter used to describe driving behavior is space mean speed. This is very important because it considers speed of vehicles traveling a given segment of roadway during a specified period of time and it is calculated using the average travel time and the length for the roadway segment. This speed is used to understand driving behavior in normal traffic flow and in daylight conditions. The data are collected on urban road tangents. These roads have the common characteristic to be single or dual carriageways with two lanes for each direction with a speed limit of 50 km/h. With a multiple linear regression, two models are developed and validated to predict speed. Statistically significant variables include traffic characteristics (flow, number of vehicles entering and leaving traffic stream) and geometric design attributes (lanes width, type of median, tangent length and type of left-lateral obstacle). This study can be useful to both traffic manager and road designers because developed models could implement design guidelines, especially regarding road tangents.