SIDRA INTERSECTION can be used to model the effect of major road upstream signals on the capacity of minor movements at intersections controlled by Stop and Give-way (Yield) signs, as well as roundabouts. For this purpose, the extra bunching parameter is used in association with the bunched exponential model of opposing stream headways. In network analysis, the program calculates the extra bunching values automatically. The method is described in the SIDRA INTERSECTION user guide.
As extensions of the HCM Edition 6 and HCM 2010 roundabout capacity models in SIDRA INTERSECTION, the effect of upstream signals is also modelled when the HCM Edition 6 and HCM 2010 model options are used although the HCM models do not use a bunched distribution of circulating stream headways.