pressure sensors at lights ?

green123

a quote from another thread

"Should I have moved out half way (the area where those "pressure sensors" are for the lights) and waited... "

never heard of these pressure sensors before
any more info on them ?

cyclopath2001

If you look closely at the road surface before before the stop line, you'll see a a grid of lines of tar which I think is where the sensor is buried.

They're designed to change the signal to green when cars are stopped at a traffic signal but to keep the signal on red, indefinitely, when only cyclists are waiting.

It's important that cars stop just before the stop line so that the car's weight rests on the sensor. Unfortunately, some motorists prefer to drive past the stop line and wait, blocking the pedestrian crossing. This leaves no weight on the sensor. This can cause a lot of delay.

TwoShedsJackson

cyclopath2001 wrote: »

They're designed to change the signal to green when cars are stopped at a traffic signal but to keep the signal on red, indefinitely, when only cyclists are waiting.

A cyclist waiting at a red light?? ahahahahhahahahahaaa etc.

But seriously, supposing there were more than three cyclists who actually paid attention to red lights and pedestrian crossings etc. seems a bit unfair to keep them on red indefinitely?

Blanchguy

Those lines are actually an induction loop which detects the metal in your car. A bike may be too small to trigger them - try stopping your bike along one side of the loop with your wheel at the corner - that's where the loop is most sensitive.

MrPudding

Blanchguy wrote: »

Those lines are actually an induction loop which detects the metal in your car. A bike may be too small to trigger them - try stopping your bike along one side of the loop with your wheel at the corner - that's where the loop is most sensitive.

Motorbikes have the same problem and as we normally stop at red lights it can be very frustrating.

I have been wondering if the induction loops for Truvelo speed detectors are sensitive enough to detect motorbikes....

MrP

Blanchguy

Probably not - but afaik they aren't used for enforcement - just statitistical and informational purposes.... If you really wanted I could probably find out!

Cookie_Monster

They are a clever piece of kit i think, yet in my area at least 2 or 3 have been revomed recently if favour of timed lights as people are unable to stop at the line correctly to activate them

MrPudding

Blanchguy wrote: »

Probably not - but afaik they aren't used for enforcement - just statitistical and informational purposes.... If you really wanted I could probably find out!

In the UK there are a type of speed camera that uses induction loops, the Truvelo. They are not for statistics they are proper speed cameras.

MrP

daymobrew

Blanchguy wrote: »

Those lines are actually an induction loop which detects the metal in your car. A bike may be too small to trigger them - try stopping your bike along one side of the loop with your wheel at the corner - that's where the loop is most sensitive.

When I lived in California and the lights weren't detecting my bike the traffic engineer suggested I tilt the bike so that it was almost on the horizontal, to have as much metal near the loop.

These days I will move across the white stop like to allow a car behind me come to a stop over the loop. I can seem them approaching in my handlebar mirror and have moved before they get to the line. Some need encouraging to move over the loop.

At a junction in Cabra there is a 'camera' on top of the lights. It seems to detect me quite well and the lights are quite responsive. I come from Dowth Ave side, turning left onto Fassaugh Ave.

alias no.9

There should have been an information campaign launched when there were introduced. Most drivers can figure it out pretty easily but there's some very dim drivers out there. The biggest problem is for filter lights, turning right in particular. The first driver usually needs to move onto the junction before the sensor recognises their presence.

You sometimes get a driver at the front of the queue who's oblivious to this, five cycles of the traffic light sequence without the filter light coming on and then the driver in front makes a reckless manouver and races accross the junction in front of traffic coming from another direction as the lights change.

The next car proceeds to drive onto the junction, activates the sensor and hey presto, the entire queue gets to progress.

alias no.9

As for cyclists, maybe there should be a road position that they can take up, with a more sensitive loop that can be marked or made common to all junctions.

TigerTim

There's one on my way to work in Tralee which is just set beyond the white line - maybe the white line was repainted at some stage!. If you wait behind the white line, the lights never change. You have to stop just astride the line & its OK. Most people seem to know but its very frustrating if a driver sits back from the white line & I'm stuck behind him. Must get on to the Council.

T.

APM

TigerTim wrote: »

There's one on my way to work in Tralee which is just set beyond the white line - maybe the white line was repainted at some stage!. If you wait behind the white line, the lights never change. You have to stop just astride the line & its OK. Most people seem to know but its very frustrating if a driver sits back from the white line & I'm stuck behind him. Must get on to the Council.

T.

this is the exact same problem which is many places in dublin, one which comes to mind is turning off the kilbarrack road onto the coast road. Cars persitantly sit behind the white line which is painted before the sensors. Have sat in a line of traffic for upwards of 4mins in the evening waiting before the first car eventually cops on. Of course beeping etc just seems rude because the light is red.

macnab

Blanchguy wrote: »

Those lines are actually an induction loop which detects the metal in your car.

Now it all makes sense. For years I thought they were triggered by weight. I wonder would a magnet on the underside of the bike do any good??

Esel

There's one at the exit barrier in work. Used to use a flattened tin can to trigger it to lift the barrier when I had no swipe card!

Also, love to see the twats who drive past the line before stopping having to wait at the red light.

Wishbone Ash

The sensors at the entrance to car parks seem to work on volume/mass rather than weight. For example, if you walk up to the barrier it will not issue a ticket but if you walk up with a large piece of chip board etc. it will issue one.

(This is presumably to prevent people from obtaining a new ticket to reduce their parking costs).

I.S.T.

Wishbone Ash wrote: »

The sensors at the entrance to car parks seem to work on volume/mass rather than weight. For example, if you walk up to the barrier it will not issue a ticket but if you walk up with a large piece of chip board etc. it will issue one.

(This is presumably to prevent people from obtaining a new ticket to reduce their parking costs).

How do you know this?! Do you regularly walk up to barriers with large pieces of chip board?!!

lostinsuperfunk

I don't think those embedded sensors are a great idea. As discussed above, they don't work for bikes or motorbikes and I remember one occasion when I was a learner and stopped about 1 m short of a red light when, after a wait of a few minutes, one of the drivers behind me had to get out and walk up to my car and tap on the window to inform me that the lights were sensor-triggered and I needed to move forward!
Surely some kind of sign wouldn't go amiss at junctions like these? I'd like to think that I'm not particularly dim, but I never realised that there were sensors under the road.

Esel

IrishSpeedTraps wrote: »

How do you know this?! Do you regularly walk up to barriers with large pieces of chip board?!!

Large pieces of clipboard if you ask me!

lostinsuperfunk wrote: »

I never realised that there were sensors under the road.

Don't worry, you are not alone. You know now though.

For bikes/motorbikes, as said above, go to the corner of the grid (it's outlined by thin tar lines). Where the junction has the red surface for bikes, it's usually behind this. There is often a (probably) decommissioned older grid in front, don't go for this one.

Personally, I put on my tin foil hat. You never know! :eek:

Wishbone Ash

IrishSpeedTraps wrote: »

How do you know this?! Do you regularly walk up to barriers with large pieces of chip board?!!

:D PM sent!

Biro

Some traffic light ones are pressure sensitive too. Many a drunken night walking home with mates we'd wait till there was no car coming, then dig the heel into the sensor and watch the light go orange then red, and the joining one go green. It would happen straight away cause there was no traffic detected on the main road. Wouldn't happen if there was a car on the main road.