COMPARISON OF PROCEDURES TO ESTIMATE CRITICAL HEADWAYS AT ROUNDABOUTS

The capacity analysis of roundabouts in Portugal is mostly done using the UK regression method. Due to its empirical and non-explanatory nature, this method has some limitations, particularly for studying innovative layouts, which has recently motivated research in Portugal into the use of capacity methods based on gap-acceptance theory. This paper describes the results of a related project: the estimation of critical headways and follow-up times at Portuguese roundabouts. For this study, gap-acceptance data were collected at six roundabouts, in two cities, and used to estimate the parameters at each entry, for the left and right entry lanes independently. Several estimation methods were used (Siegloch, Raff, Wu, Maximum Likelihood and Logit). The results have revealed important specificities of the methods that have significant effects on the results and therefore on the capacity estimate exercises. The comparison of the estimates with reference values from several countries indicates significant differences, suggesting the existence of relevant driving style differences, which implies that locally calibrated, country-specific, parameters are required for capacity calculations.

[1]  Ola Hagring,et al.  ESTIMATION OF CRITICAL GAPS IN TWO MAJOR STREAMS , 1998 .

[2]  Hesham Rakha,et al.  Empirical Analysis of Effects of Wait Time and Rain Intensity on Driver Left-Turn Gap Acceptance Behavior , 2010 .

[3]  W Siegloch,et al.  DIE LEISTUNGSERMITTLUNG AN KNOTENPUNKTEN OHNE LICHTSIGNALSTEUERUNG , 1973 .

[4]  R L Pretty,et al.  OVERTAKING ON TWO-LANE RURAL ROADS , 1968 .

[5]  George F. List,et al.  Roundabouts in the United States , 2007 .

[6]  Wayne Kittelson,et al.  IMPLEMENTING THE MAXIMUM LIKELIHOOD METHODOLOGY TO MEASURE DRIVER'S CRITICAL GAP , 1997 .

[7]  R M Kimber,et al.  THE TRAFFIC CAPACITY OF ROUNDABOUTS , 1980 .

[8]  Nagui M. Rouphail,et al.  Comparison of Capacity Models for Two-Lane Roundabouts , 2003 .

[9]  Gary A. Davis,et al.  Field Study of Gap Acceptance by Left-Turning Drivers , 2004 .

[10]  Lambertus Gerrit Hendrik Fortuijn,et al.  Turbo Roundabouts , 2009 .

[11]  A Weinert,et al.  ESTIMATION OF CRITICAL GAPS AND FOLLOW-UP TIMES AT RURAL UNSIGNALIZED INTERSECTIONS IN GERMANY , 2000 .

[12]  Werner Brilon,et al.  USEFUL ESTIMATION PROCEDURES FOR CRITIAL GAPS. , 1997 .

[13]  Tomaž Tolazzi.  THE CONTRIBUTION TO THE PROCEDURE OF CAPACITY DETERMINATION AT UNSIGNALIZED PRIORITY-CONTROLLED INTERSECTIONS , 2004 .

[14]  Abishai Polus,et al.  Evaluation of the Waiting-Time effect on Critical Gaps at Roundabouts by a Logit Model , 2005, European Journal of Transport and Infrastructure Research.

[15]  Rod Troutbeck.  EVALUATING THE PERFORMANCE OF A ROUNDABOUT , 1989 .

[16]  A. Polus,et al.  Critical Gap as a Function of Waiting Time in Determining Roundabout Capacity , 2003 .

[17]  R. Tapio Luttinen.  Capacity and level of service at Finnish unsignalized intersections : S12 Solutions to improve main roads : S12 Pääteiden parantamisratkaisut , 2004 .

[18]  Tomaž Tollazzi,et al.  New Type of Roundabout: Roundabout with “Depressed” Lanes for Right Turning – “Flower Roundabout” , 2011 .

[19]  Pelin Çalişkanelli,et al.  Comparison of different capacity models for traffic circles , 2009 .

[20]  R T Luttinen,et al.  Capacity and level of service of Finnish signalised intersections , 2002 .

[21]  Ola Hagring.  A further generalization of Tanner’s formula , 1998 .

[22]  Ning Wu,et al.  Equilibrium of Probabilities for Estimating Distribution Function of Critical Gaps at Unsignalized Intersections , 2012 .

[23]  Álvaro Seco,et al.  Estimating the Parameters of Cowan’s M3 Headway Distribution for Roundabout Capacity Analyses , 2012 .

[24]  Ana Bastos Silva,et al.  Estimation of Critical Headways at Unsignalized Intersections: A Microscopic Approach , 2012 .

[25]  Rahmi Akçelik,et al.  A review of gap-acceptance capacity models , 2007 .

[26]  António Luís Pimentel Vasconcelos,et al.  Capacity of normal and turbo-roundabouts: comparative analysis , 2014 .

[27]  Mustafa Özuysal,et al.  Applicability of Various Capacity Models for Single-Lane Roundabouts in Izmir, Turkey , 2007 .