Arrival Turning Flows
Average Daily Traffic
User Guide > Entry Capacity
The current version of Rodel incorporates two capacity options: Geometric and HCM (6 or 10).
HCM uses the Capacity Equations from the Highways Capacity Manual.
The geometric Rodel Capacity Algorithms are an extension of Kimber’s equations that model US conditions.
The enhanced geometric capacity model has been developed to model North American roundabouts; for example, single lane roundabouts with very wide single lane entries (to accommodate large trucks) that are wider than the receiving section of the circulating road. (Entries wider than the circulating road are not permitted in the UK.)
The geometric capacity model has also been applied to situations where the number of opposing circulating streams differs from the number of entry streams. The effect on entry capacity is modest with low circulating flows but increases as circulating flows increase. (This was not in the original model as UK Roundabout Guides required that the number of circulating lanes were not less than the number of entry lanes, which is now no longer the situation, so the model has been updated.)
Several Capacity Modifiers have been added to the enhanced model:
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