For very low-volume applications, TWSC and AWSC are easier and less expensive to implement. Since roundabout operation is not periodic, it is not possible to coordinate the operation of roundabouts on an arterial route to provide smooth progression for arterial flows. Roundabouts offer the least positive form of control. Each vehicle entering the intersection must yield to all traffic that has already entered. Therefore, roundabouts are not the solution to all traffic problems at all locations.
Careful study is required to identify the most appropriate control method at any given location.
No such warrants or requirements exist for roundabouts.