Thursday, February 25, 2010

Making a bad junction worse

In a conversation with a friend of mine in the UK this week, I was reminded of an issue which plagues the road system over there - traffic lights on roundabouts. Roundabouts (traffic circles to the Americans) are a very clever intersection design that prevents traffic clogs by allowing the traffic to keep flowing (remember my series of driving mantra - traffic is like a flowing river?). Except that in too many cases now, local councils have littered roundabouts with traffic lights. This negates the whole purpose of the roundabout in the first place, and actually makes the whole junction far worse than it would be just to have traffic lights. Why? Because traffic backs up on the roundabout - stopped by the lights - which blocks the entire junction for those trying to get on or off. Worse - when the lights controlling the flow of traffic on to the roundabout are synchronised with those controlling the flow of traffic off, all it does is result in a constantly moving blockage. Nobody ever gets the chance to get on at the non-light-controlled entries because the roundabout is permanently blocked. This in turn results in huge tailbacks and traffic jams on all the roads leading up to the junction. I remember one on my daily commute when I used to live in England. It was in Bracknell at the end of the A329(M). It was a bloody nightmare because it was always blocked. Even on the motorbike it was hard to thread my way through the traffic. Councils need to learn that they need either traffic lights, or a roundabout, not both.

1 comment:

pjvenda said...

hah, so true. What about roundabouts that have been "cut through" (for being priority routes, I guess) or others in which not all accesses are controlled by traffic lights?

[Like this one: http://maps.google.co.uk/maps?f=q&source=s_q&hl=en&geocode=&q=headington+roundabout&sll=53.800651,-4.064941&sspn=21.192481,39.506836&ie=UTF8&hq=&hnear=Headington+Roundabout,+Oxford+OX3+9,+United+Kingdom&ll=51.76274,-1.196373&spn=0.005399,0.009645&t=h&z=17]