This is an idea to physically enforce a minimum speed in the fast lane of a motorway.

When the fast lane enters a bend in the road it starts banking up at an angle so that cars are required to keep above a certain speed to provide the necessary centripetal force to stop them from moving down to the next slowest lane. The required angle of incline would be worked out for each bend depending on the radius, and the chosen minimum speed.

Unfortunately this would only work on a road with bends. On straight roads, artificial bends would have to be put in place. (Or perhaps some sort of sticky treacle-like substance could be smeared over the road which allows fast moving cars to hydroplane (or treacloplane) while cars below the speed threshold get impeded by the viscosity).
-- stupop, May 29 2002

Road Safety Research Reports http://www.mrwa.wa....gher_open_speed.htm
see first line [stupop, May 29 2002, last modified Oct 21 2004]

You're right - the mass cancels out. Amended.
-- stupop, May 29 2002


And the weight of heavy traffic could flatten it, so you don't fall to your death when slowed down in traffic jams, perhaps?
-- pottedstu, May 29 2002


Maybe I'm wrong, but at least IN AUSTRALIA the fast lane doesn't entitle you to drive AS FAST AS YOU LIKE. Anyone in the so called "fast lane" should be doing a reasonable speed (up to the speed-limit) but it's the impatient ones who screw things up for everyone else. In Australia, most "fast lanes" as you call them are used only for passing, so if you ARE stuck behind someone, you just move around them.
-- thelumberjack, May 29 2002


Likewise in UK. The right-most lane (remember we drive on the left) of a three-or-more lane motorway is the overtaking lane. It is only for overtaking, and the 70mph limit still applies.
This is still a cool idea though, and useful for two lane roads. I'd like to see it on the Devon Expressway (A38 between Exeter and Plymouth).
-- angel, May 29 2002


[thelumberjack] I thought that in the Northern Territory IN AUSTRALIA there was no maximum speed limit on open roads, therefore allowing you to drive AS FAST AS YOU LIKE. I'll try & find a link.

It would require a change in the law to implement in other areas such as the UK, or other parts of Australia. Otherwise the minimum speed could be set 5-10 mph below the limit.
-- stupop, May 29 2002


Instead of a curve, make the fast lane do an overhead loop; the slow pokes would drop off at the top.
-- FarmerJohn, May 29 2002


There's a problem with inserting curves into currently-straight stretches. In fact, it's a problem even in already curvy roads that have both right and left curves (i.e., nearly all the roads that actually get you somewhere, except for "beltway" roads around cities). For it to work as described, the fast lane would have to be on the right for left curves and on the left for right curves. So the fast traffic would have to be constantly swapping lanes with the slow traffic, which I think would cause enough congestion to more than overcome the benefits.

I suppose this could be overcome by modifying the idea so that when the road curves one way slow cars in the fast lane drop into a slower lane, and when it curves the other way, they drop off the road altogether. But that doesn't solve the problem nearly as elegantly.
-- beauxeault, May 29 2002


Make that a ramp and gap in the road.

A conveyor belt could feed a compactor with the slow vehicles that fail to make the jump.
-- neelandan, May 29 2002


I've often wondered if it would be possible to build a road where, due to precise construction of banking turns, etc., steering would be all but unnecessary.
-- phoenix, May 29 2002


Just wanted to point out that EVERY lane, with the exception of the inside lane, is only for overtaking, not just the "fast lane."

Also would like to put forward the opinion that it is stupid to have three lanes with an identical speed limit. There's no point overtaking if there are three cars spread out doing 65, 67 and 69 mph.

If everyone bore these in mind, and were sensible, you could drive as fast as you like down most motorway/freeway, and be able to overtake with relative ease, before turning back to the inside lane.
-- yamahito, May 29 2002


beauxeault: The problem with curves in either direction could be solved like this: by having all curves starting in the *same* way, but looping round and under the road as appropriate. To take the UK as an example, all curves would go to the left. If you actually wanted to go left, it goes left through 90 degrees then straightens out. If you wanted to go right, the road curves left through 270 degrees, taking you in a 3/4 loop before straightening out.
-- Saveloy, May 29 2002


<killjoy>I wonder (without dragging out my physics books and my calculator) if the proposed added curves would lengthen the road to the point where it would take the same amount of time to get somewhere as if you drove a bit more slowly on a straight road.</killjoy>
-- half, May 29 2002


I like the treacle idea but maybe it should be highly corrosive if in contact for more than a few seconds otherwise you would get already slow-moving cars stuck in the fast lane blocking it completely.
-- The(n)iceman, Mar 24 2004



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