Truvelo road markings

[Windlepoons]

http://maps.google.co.uk/?ie=UTF8&ll=51.183567...

It seems this camera doesnt use the normal road markings, how does it measure distance traveled?

[snoopstah]

It and every other Truvelo in the country (but that doesn't mean the road painting crews don't get enthusiastic occasionally and randomly paint some extra lines).

It uses induction loops and triggers the camera when the car wheels are directly on them -- unlike Gatsos which use radar and could be confused by multiple vehicles etc. That's why (as I understand it) they don't need to verify your speed by taking a double photograph.

[vit4]

Similar topic, but there's a gatso near mine. The road's just been resurfaced, and the markings are not yet painted. Would this mean it couldn't get the speed correct?

[Mr Will]

IIRC the three induction loops are the faint black lines, then the camera calculates your speed and takes a picture when it thinks you will be on the middle of the three white lines. The other two white lines are the outer tolerances, if you are outside these then it has calculated your speed wrong and you are safe.

[Puddenchucker]

vit4 said:

Similar topic, but there's a gatso near mine. The road's just been resurfaced, and the markings are not yet painted. Would this mean it couldn't get the speed correct?

Nope.

Edit to add:
Home Office Archive

Edited by Puddenchucker on Monday 24th May 22:34

[Boosted LS1]

^ Yes. As you pass over the induction loops it obtains your speed, primary evidence. Then it takes the photograph when it assumes your wheel will be within the 3 white lines based upon your speed. This is the secondary corroboration iirc. Gatso markings are just done to confuse imo.

ETA, the inductive loops only apply to the nearside lane. You don't have to drive over them if the offside lanes clear. I 'overtake' a truvelo sometimes on a road near me.

Edited by Boosted LS1 on Monday 24th May 22:00

[mudster]

Truvelos actually use piezo electric sensors in the carriageway rather than induction loops. These work on pressure of the wheel rather than sensing a metallic object (as an induction loop would). Placing pressure on a piezo sensor causes a voltage across the sensor.