Magic Roundabout

http://www.strum.co.uk/wessex/brunpic.htm

Allegedly, this sort of thing is officially called an OlympicRoundabout?.

AAAAAAGGGGGGGHHHHHHHHHHH!!!!!!! How does anyone survive that during morning commutes? -- PeteHardie

To quote from http://www.swindonweb.com/life/lifemagi0.htm

And magic it certainly is. Though it may confuse or amuse new visitors and baffle American tourists, the average Swindonian finds that his or her passage through one of the town's busiest junctions is actually quite fluid, even at peak times. Twenty-five years on, the Magic Roundabout still works, despite ever-increasing volumes of traffic.

That one is easy. Try the monster in Hemel Hempstead - 6 mini roundabouts, and NO middle island - you can turn right if you dare!

Oh no, EpiCycles!

What's the point of the counterclockwise circle on the inside? No one should have to go in both directions around a roundabout -- that just increases the chance of collisions at each of the mini-roundabouts, as well as your chances of getting lost and missing your exit! Eliminate the inner circle and epicycles (YAGNI), have all four lanes of traffic go clockwise (DTSTTCPW), and each car will have to merge into rotary traffic only once and exit only once (OAOO), which is simpler and far more predictable. Even though some people might now have to go 4/5 of a rotation to get to their exit, instead of just 1/5, but if anyone complains about that they're driving in the wrong country.

On a simple roundabout weight of traffic on a busy route can keep traffic from a less busy route joining the roundabout. This arrangement stops that happening.

Cool. I can see how that can help if most of the traffic is going counterclockwise, say, SW to E - then cars can still enter the inner circle from the SE because of the mini-roundabout at the entrance there. But what if most of the traffic is going clockwise, e.g. NE to SE - how do cars enter from the E when all the traffic is blocking them from entering even the mini-roundabout?

If there was a lot of traffic going from NE to SE traffic that would be so, however NE to NW and NE to SW traffic would take the inner circle so that would make life easier for traffic entering from the east.

- The basic idea of the Hemel roundabout is to ignore the central roundabout and treat each mini-roundabout around its periphery as a singular entity. Therefore, the issues of traffic blocking cars from entering very rarely arises. In fact, the biggest issue with Hemel's Magic Roundabout would be the cars coming down Midland Hill and making a u-turn around a single mini-roundabout, as this catches out the unwary looking for a gap to their right.

Next question: what's that mini-roundabout on the western edge all about? It appears to have only two segments connected to it!

It used to connect to a road which passed underneath the old BP HQ (since demolished). Recently the road has been reopened for buses only. --DanRos?