Truvelo question

[moosepig]

Near where I work a stretch of road has been resurfaced. Along this stretch (30 limit) is a Truvelo. The sensors haven't been relaid in the new tarmac and the white stripes haven't been painted across the carriageway... am I correct in presuming that this camera is effectively dead, and that if it did go off the lack of stripes mean that no conviction could be secured on its evidence?

[mechsympathy]

AFAIK a Truvelo doesn't need corroborating stripes. And how do you know the sensors have been removed? They're normally visible because of the shiny bitumen strip where the road has been repaired. You wouldn't need this if the road was laid fresh over the sensors... Shirley?

[moosepig]

AIUI the Truvelo detects speed using piezo sensors in the road, then calculates when to photograph you so that your front wheels are over the white lines in the road (a series of narrow lines that stretch across the carriageway, not distance markers like with a gatso). For any evidence to be admissible, there has to be corroboration, in other words something that backs up the initial assessment of speed. In the case of a gatso it's the 2 photos at a timed interval; for a truvelo it's a single photo timed to show your wheels on the lines.

Like this in fact:


I don't know how deep the sensors are laid (anyone?), but as you rightly point out you can normally see the marks where the tarmac has been sealed over them. In the above picture you can see them just before and after the rear wheel of the car. This particular resurfacing involved scraping up the old tarmac first, which I would imagine ought to have dug up the sensors too, surely they can't be that deep or they'd lose accuracy?

So - even if the sensors are somehow still there, AIUI this camera can't be used to prosecute you as the white lines are missing. Because the location of the sensors is now unknown (if they're still there) surely no white lines can accurately be laid down anyway. Yet the camera is still there, and people are still jamming on the anchors and slowing down to 25 for it

Just looking for confirmation of my suspicions that this is effectively a dead camera.

Edited by moosepig on Thursday 15th March 15:17

[SS2.]

AIUI, any unmanned speed detection device requires primary evidence and a secondary, corroborating check. As you correctly pointed out, at a Truvelo installation this takes the form of 3 parallel lines painted on the road surface.

No timing lines = no corroboration of primary evidence = insufficient evidence to prosecute.

[munchintoz]

Hmmm..... Now wheres that old pot of bitumen paint?

[mechsympathy]

But how do 3 white lines demonstrate corroboration?

[V10Mike]

Because the camera takes a picture at the time predicted for the car to be over the white lines, based on the speed measurement. Hence car over white lines=speed corroborated.