Do Roundabouts Reduce Traffic Volume?
Do Roundabouts Reduce Traffic Volume?
(OP)
Hello All,
A developer is putting in a collector road that will run roughly parallel to an unimproved arterial but will cut about one-half mile off a commuter route. The adjacent neighborhood where the collector will connect is concerned about cut-through traffic using this new route.
The developer has proposed using three large roundabouts spaced evenly over the one-mile segment of new road. The developer is arguing that these three roundabouts will discourage any cut-through traffic from using this new road.
Does anyone know of any research related to the deterrent effect of roundabouts on through traffic? There seems to be evidence that roundabouts cut accident rates at busy intersections but very little has been written about the effects of roundabouts on traffic volume.
Thanks,
Woody Carr
Chesterfield County Virginia
A developer is putting in a collector road that will run roughly parallel to an unimproved arterial but will cut about one-half mile off a commuter route. The adjacent neighborhood where the collector will connect is concerned about cut-through traffic using this new route.
The developer has proposed using three large roundabouts spaced evenly over the one-mile segment of new road. The developer is arguing that these three roundabouts will discourage any cut-through traffic from using this new road.
Does anyone know of any research related to the deterrent effect of roundabouts on through traffic? There seems to be evidence that roundabouts cut accident rates at busy intersections but very little has been written about the effects of roundabouts on traffic volume.
Thanks,
Woody Carr
Chesterfield County Virginia





RE: Do Roundabouts Reduce Traffic Volume?
The roundabouts may have some "traffic calming" effect, though.
How large is large? Research has shown that safety decreases as the roundabout's diameter increases. It shouldn't be larger than it has to be to handle the traffic that will use it.
RE: Do Roundabouts Reduce Traffic Volume?
Regards,
Dragon
RE: Do Roundabouts Reduce Traffic Volume?
Woody
RE: Do Roundabouts Reduce Traffic Volume?
RE: Do Roundabouts Reduce Traffic Volume?
I don't understand ontwerp's question. If you are asking why people stop so far into an intersection, I would imagine it's to be in the best position to get through it when the light changes. Or to minimize the amount of time lost while stopping at a sign. People largely look at traffic controls as a major inconvenience.
Tom
RE: Do Roundabouts Reduce Traffic Volume?
RE: Do Roundabouts Reduce Traffic Volume?
RE: Do Roundabouts Reduce Traffic Volume?
Perhaps I'm being picky about semantics, but speed BUMPS should not be used on public roadways. Courts of law have ruled against the use of speed bumps on the basis of their physical charactersitics and potential for damage to vehicles driving reasonably and prudently. Speed HUMPS are a ligitimate device.
RE: Do Roundabouts Reduce Traffic Volume?
"The best traffic deterant for cut through traffic is speed bumps or speed humps. People ignore stop and yield signs, but there is no way around a speed hump. They also help keep speeds down."
Apparently your parents are not equipping their children with four wheel drive trucks as they are in our area.
The shoulder, ditch, and adjoining yards are all fair game for bypassing the speed bumps.
RE: Do Roundabouts Reduce Traffic Volume?
Other measures such as breaking up long tangents, narrowing intersection approaches, curvilinear design, can be built in if the development is not yet finalized.
RE: Do Roundabouts Reduce Traffic Volume?
priority junction (give way)
signalised junction (traffic lights)
roundabout
signalised roundabout
However there are grey areas between the uses depending upon the size and geomtery.
The upshot is will delay on the atrerial route be greater than the signalised route, if it isnt you will expect a shift to people using the new areterial route. It is purely a function of delay. You will need to run the calcs. We use Arcady produced by the TRL in the UK, to analyse delay and ratio of flow to capacity.