Interesting: Does the US design of roundabouts not use traffic flow analysis at the entries and exits of the roundabouts to obtain required geometry values.
The UK design relies on these widths to reduce or increase the flow of vehicles through a roundabout and thus safety.
Design elements such as tapers and widening at the entries and exits are fixed by calculations made in software which evaluates the traffic flows from each leg and then gives the required geometry constraints, entry/exit curve radius, flare lengths and tapering widths.
If not I want to design roundabouts in the US : )
Mike Evans
Civil3D 2022 English
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