Prediction of Design Hourly Volumes on Roads with a Dominantly Local Character of Traffic Flows

The analysis of design hourly volumes is one of the fundamental preconditions for the procedures of designing and evaluating road design solutions. In most cases, on road sections with a predominantly local character of traffic flows, there is an absence of automatic traffic counters, and determining the design hourly volumes is very difficult. In this regard, defining the design hour and developing a model for predicting design hourly volumes based on short-term traffic counts are the primary goals of this paper. Based on data from road sections with an automatic traffic counting system, the design hour is within the range of the 8th to the 16th hour of ordered hourly volumes. After further analysis, the 10th hour was adopted as the proposed value for determining design hourly volumes in local conditions. The prediction model is based on linear regression, i.e. modelling the relationships between the dependent variable, design hourly volume and independent variables, peak traffic volumes during design days. The model was tested for 10th and 30th hours in order to verify the model in local conditions as well as in accordance with the recommendations of the Highway Capacity Manual. The research results indicate that the average percentage deviation of the model-estimated design hourly volumes based on short-term traffic counts compared to the actual realised volumes ranges from 8% to 9%, depending on the analysed design hour.