Civil and Environmental Engineering Commons^™

Gap Acceptance Parameters For Hcm 2010 Roundabout Capacity Model Applications In Italy, A. Gazzarri, Michael T. Martello, Antonio Pratelli, Reginald R. Souleyrette

Civil Engineering Faculty Publications

This paper deals with the field data observation and successive application of estimation procedures in order to estimate follow-up headway and critical headway at roundabouts. Average follow-up headway and average critical headway are two key parameters in the new roundabout capacity model presented in the 2010 edition of the Highway Capacity Manual (HCM). The HCM 2010 capacity model was developed as an exponential regression model with parameter estimates based on gap acceptance theory. Gap acceptance models are strongly affected by driver behaviour and local habits. Follow-up headways can be field measured, while critical headway cannot be obtained directly. The paper …