question about the road....
 

right...

as u approach the traffic lights u have these wierd rectangular shapes cut out in the ground that are lined by tar

what are those for?

Re: question about the road....
 

Strain Gauges. They sense the weight of a car at a set of traffic lights waiting whilst they are on red.

I pass through the lights on Dill Hall at the junction with Hyndburn Road every day. Before 7am, the light switching is controlled by the strain gauges recognising a car waiting to pass through the junction. After 7am, when the flow of traffic increases, the automatic switching sequence is put into play. If this sequence fails during the day, it is chaos.

Re: question about the road....
 

I didn't realise that there was actually a technical name for them, but I knew what their function was - they have them all over the place.

Know I know what they are called I can surprise my friends and amaze my enemies...! ;)

Re: question about the road....
 

Strain gauges are used in many engineering applications. Most noticeably in weigh-bridges. Here endeth the lesson... for now.

Re: question about the road....
 

It looks like there are some in that dead end bit of St James St - what would be their function there?

Re: question about the road....
 

It wasn't always a dead end. I remember when there was traffic lights there.

I was talking to a guy at a motorcycle rally a couple of years ago who worked on the private road over in Yorkshire that connects two motorways(Can't remember which one it was exactly). Basically he was telling me that the company who own the road charge the DOT for the number of vehicles that travel along it. He was saying that the induction stuff they use is getting close to telling what type of car has passed due to its magnetic signature. Quite scary really.

Re: question about the road....
 

mmm very scary. From a conversation I had earlier today I can see how they can be of use in an accident situation too when a driver may insist they haven't done something (and then reversed) because they road would "know" that they had.

Re: question about the road....
 

I thought rather than strain guages sparks, these sensors detected the change in their hysteresis caused by the metal work of the car in a similar way to a metal detector?

Re: question about the road....
 

Try this for an explanation
http://auto.howstuffworks.com/question234.htm