This study considers the problem of estimating the reduction of roundabout entry capacity caused by pedestrian zebra crossings. An empirical procedure is developed on the basis of field observations collected at an urban four-leg roundabout located in Padova (Italy). The disturbance caused by pedestrians to approaching traffic is measured using crosswalk occupancy times, rather than pedestrian volumes like in previous studies. The proposed method leads to the determination of a capacity reduction index, which can be applied in operational analyses to obtain realistic estimates of roundabout entry capacities taking into account the impact of pedestrian crossings. Also, the possible effect of introducing pedestrian-actuated signal control on zebra crossings is evaluated, using simulation, with reference to alternative pedestrian volume and signal timing scenarios.
