Those wires across the road...

Zascar

Possibly a stupid question - but can anyone tell me more about those wires you see sometimes across the road - two lose rubbery type. I assume they are for counting traffic, but how exactly do they work and what do they do with the data?

eeguy

Pneumatic road tubes.

The tubes change in pressure as a vehicle passes over.
Heavier vehicles = higher change

They're deployed in pairs to measure direction of travel and possibly speed.

Jimbob1977

Zascar wrote: »

Possibly a stupid question - but can anyone tell me more about those wires you see sometimes across the road - two lose rubbery type. I assume they are for counting traffic, but how exactly do they work and what do they do with the data?

Yes, they are for counting traffic. Every record will be divided by two (as a car has front wheels and back wheels)

I'd expect the wires are fitted to a sensor box that relays the information back to the council or NRA.

The data would show trends, ie this road is very busy from 7am to 9am and traffic volumes have spiked by 30% year on year.

Then the planners might think about road widening or new roundabouts, traffic lights, etc. Or a relief road to take the pressure off

sKeith

They are good for skidding on. You need to jam on at the right moment for it to work. You need a car without ABS for this to work.

prinzeugen

Traffic counters. Been around for years. On the older versions there was a a counter you could watch (bit like the counter on a cassette player) that would go up as each vehicle passed.

As kids we used to jump on the lines to see who could get the numbers to go up the fastest.

L1011

Bill Gates first entry in to software was writing analysis gear for those - the early versions recorded the air changes on paper tape, "Traf-O-Data" could read the tape and give you the figures. Oh what horrors that released on the world!

The permanent ones use magnetic induction, those are the wires *in* the road.

prinzeugen

L1011 wrote: »

Bill Gates first entry in to software was writing analysis gear for those - the early versions recorded the air changes on paper tape, "Traf-O-Data" could read the tape and give you the figures. Oh what horrors that released on the world!

The permanent ones use magnetic induction, those are the wires *in* the road.

Slightly off topic but there are few magnetic induction loops on the roads even for traffic lights.

Most use the same system as the old traffic counters. I once did 1000's of miles a week as a courier and know you had to run along the tar line not sit in the box.

The lights won't change otherwise.

Most new build roads use magnetic but the majority are still pressure based.

How old the road surface is and the age of the grey box is a clue.

Often had to tell a Taxi at 2am to sit on the tar line having never got a green after 3 sequences.

L1011

Plenty of taxis seem to position themselves such that it doesn't detect them when it's quiet...

Capt'n Midnight

prinzeugen wrote: »

Traffic counters. Been around for years. On the older versions there was a a counter you could watch (bit like the counter on a cassette player) that would go up as each vehicle passed.

I was told that on older versions the puff of air would blow some sand into a container and that's how they'd work out how many cars passed.

HonalD

Capt'n Midnight wrote: »

I was told that on older versions the puff of air would blow some sand into a container and that's how they'd work out how many cars passed.

Where did you hear that Captain?

HonalD

prinzeugen wrote: »

Slightly off topic but there are few magnetic induction loops on the roads even for traffic lights.

Most use the same system as the old traffic counters. I once did 1000's of miles a week as a courier and know you had to run along the tar line not sit in the box.

The lights won't change otherwise.

Most new build roads use magnetic but the majority are still pressure based.

How old the road surface is and the age of the grey box is a clue.

Often had to tell a Taxi at 2am to sit on the tar line having never got a green after 3 sequences.

I'm afraid this isn't true. The majority 99% of loops cut into roads in Ireland are inductive loops. Sometimes, the sensitivity of a loop may not pick up different classes of vehicles but the loop detectors can be reconfigured once a problem is identified.

Cyclists often complained that they couldn't trigger the lights but this was usually that the induction limits were not set low enough to identify when a light framed bike crossed them. Fibre framed bikes are obviously an object that won't be picked up easily.....but sure it's only a red light...................;)

prinzeugen

HonalD wrote: »

I'm afraid this isn't true. The majority 99% of loops cut into roads in Ireland are inductive loops. Sometimes, the sensitivity of a loop may not pick up different classes of vehicles but the loop detectors can be reconfigured once a problem is identified.

Cyclists often complained that they couldn't trigger the lights but this was usually that the induction limits were not set low enough to identify when a light framed bike crossed them. Fibre framed bikes are obviously an object that won't be picked up easily.....but sure it's only a red light...................;)

Rathgar Ave.. That is all! BS!

Try it out. I cycle to work and can change the lights at the Harold's Cross junction by running up the tar. Do it daily. Or it may be you have the road positioning all wrong?

Keep left!

HonalD

prinzeugen wrote: »

Rathgar Ave.. That is all! BS!

Try it out. I cycle to work and can change the lights at the Harold's Cross junction by running up the tar. Do it daily. Or it may be you have the road positioning all wrong?

Keep left!

Sorry but you'll have to explain that a bit more please (what's BS?)

If you are saying that you find that by cycling along the edge of the loop shape in the carriageway that you can activate the signals then yes, I'm not surprised that this works as you are giving the loop every opportunity to detect the bike. If you only traverse the loop then, depending on the sensitivity, the bike may not be detected. Am I right?

But as I stated before, your comment that there are " few magnetic induction loops" is inaccurate.

veryangryman

Could people manipulate the data easily on these?

I mean just jump on them 1000s of times to make it look like the area requires a super highway bypass of it?

josip

veryangryman wrote: »

Could people manipulate the data easily on these?

I mean just jump on them 1000s of times to make it look like the area requires a super highway bypass of it?

You'd have to be a very angry man to do this day in day out at similar times for multiple years.
I would assume that any outliers in the data are discarded.

Dardania

L1011 wrote: »

Plenty of taxis seem to position themselves such that it doesn't detect them when it's quiet...

noticed that too... more dwell time, so greater chance of being hailed when empty? Or, if a fare in the car, longer time to charge them?

L1011

Dardania wrote: »

noticed that too... more dwell time, so greater chance of being hailed when empty? Or, if a fare in the car, longer time to charge them?

Longer time to charge the mug of a customer is all that makes sense. Meter goes to time under a specific speed