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Maryland were probably most forward on this and were able to show me a number of modern roundabouts that appeared to be working well. Some of these were at freeway interchanges which usually represent excellent locations, providing easy U-turning facilities for lost drivers and for policing and servicing the freeways. There is a need to standardise signing of modern roundabouts, in particular the sign to direct traffic to go counter-clockwise around the circle; I would recommend the sign nearest equivalent to the UK turn right sign (UK dia 606) (white arrow on blue circle) and not the worded "ONE WAY". We examined some sites locally for prospective retrofit to mini-roundabout and there is a very suitable site in Brookeville a T-intersection currently with STOP on two of the three approaches. We looked at some lightly trafficked intersections in Baltimore currently being controlled by 2-way and 4-way STOPs and traffic circles; I have to conclude that this form of intersection control works in the environment concerned but I would be worried about mixing this form of intersection control with mini/small modern roundabouts in the same area on account of possible confusion. A clearer form of signing to distinguish between the two forms of intersection will become necessary as mini-roundabouts are introduced.
At Vermont I was shown a small roundabout in Montpellier (sorry - no picture, it was dark) which appeared to be operating well despite some very strange signing. I understand that there was much controversy about its installation leading to the peculiar signing arrangement, but the scheme works well. There is a large truck apron on this site ensuring that speeds of light vehicles are well controlled. After the seminar I was escorted to the studios of Channel 17 for a television interview on the potential for the use of roundabouts to improve communities; (more serious concentration after a long seminar and the first TV interview I have done). I was later escorted around parts of Burlington where mini-roundabouts are being given serious consideration as part of regeneration, and we looked at ways of slowing down the traffic through Hinesburg as part of developing the village and creating interest in it rather than have traffic pass through without noticing the place often at excessive speed. Michigan is preparing for roundabouts and actively considering them at a number of locations. We had a chance to see a few of their prospective sites before the seminar and there are several opportunities associated with redevelopment. Dimondale village in particular are now looking at two sites which would appear to be suitable, one is a classic square intersection with wide approaches and relatively small corner radii, the other is a left hand splay T-intersection with surprisingly well balanced traffic movements. This scheme has now been installed and is working well. A part of Lansing on the riverside walk being developed is another area with great potential.
Dimondale mini-roundabout - the
first in the western hemisphere! We also looked at a number of sites in the MSU campus; they have two roundabouts conforming very closely to the European design but they need yield lines and some hatching; there is an opportunity for a superb double roundabout at the Spartacus statue; and there are other intersections which pretend to be roundabouts but are not but desperately need reshaping into roundabouts. Brief Summary My special thanks to Tony Redington (Vermont) , Ed Waddell (Michigan, now Ourston Roundabouts) and Tom Hicks (Maryland) for arranging and coordinating the event. As always I seem to learn more from delivering my seminars because of the wide range of experience that others bring. In particular the careful design and size of the truck aprons has clarified a serious issue of design in the UK for mini-roundabouts at crossroads and that is the inadequate size of our current mini-roundabout central islands. At 4m these are rarely sufficient to give anything like adequate deflection for crossing streams.
Also, at the sites I saw, the Americans are not making the mistakes we have made (and continue to make) over crossfalls on the circulatory roadway - their roundabouts are not sunk partly out of sight as we do in the UK - this is pleasing. There is a need for some standardisation on signing and lining (no standard yield line yet). America has a vast backlog of "unbuilt" potential modern roundabouts; Ed reckons about 25,000 would just about catch up with (western) Europe. There are huge casualty savings possible and I look forward to further visits to the USA if this would be helpful in accelerating the roundabouts' installation process and help to clear the fog of scepticism and mistrust. That further visit came in May 2008, after a number of visits by our American friends to the UK to try to catch up on where were. This was the national roundabout conference sponsored by the Transport Research Board. It was preceded by a roundabout workshop sponsored by Ourston Roundabout Engineering. Links to other pages: Clive Sawers - October 2008 |
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