FalloutJack said:
[Does Europe have any cloverleaf roadways? You know, like this?
We do have a few, but it's the roundabout thing in reverse I think. They just don't work with us and our mindset, or how our highways work, for some reason. Also, apparently, although they're very efficient of space and engineering requirements (only needs one simple earth-bank-and-flat-span bridge), they're a traffic, navigation and safety nightmare. You get tremendous slowdown and potential for trouble as drivers entering one bit of road have to weave around those coming off of it 100 yards later, and the tight curves and potentially bad cambering don't do trucks any favours. And, of course, regardless of where you're going, you have to turn right (or left, in UK)... and if it's the really simple, cheap version, to go ACTUAL right you have to go around three leaves of the clover...
I think continental europe may have a few, but I can only think of two, maybe three in Britain. One is on a general-class (but divided) highway about thirty miles south of me, in the provincial town of Redditch, where I've gone around a full four-leaf 1440-degree tour (ending up going the same way) just for the novelty of it after noticing it on the map whilst route planning. Another is on a meeting of a couple of motorways where the amount of turning traffic is quite low, but still needed to be cheaply provided for in all directions in a very limited space.
Instead we tend to either go for interrupted-flow solutions (long on/off ramps leading to/from a flyover/underpass with either a big roundabout, or plain ol' crossroads with or without lights), or more fancy shapes like trumpets, or a pair of little islands + diamond-split sliproads + a single bridge (the "dumbell"), or all manner of crazy free-flowing solutions that look like the brainchildren of a basketweaver on meth. It sorta works, though it's surely more pricey.
(One way to tell if a junction is a cheap, old skool, easily engineered design: does it appear on the M6 Toll? I think that might actually have a cloverleaf somewhere on it. It's certainly got an overdose of Trumpets, which are the next cheapest/dangerous/confusing thing but get rid of the traffic-weave issue. Ironic, given how much of a ghost town that road is)