Speeding Fines

[Graeme]

Speeding on bridges

I recently received a fine for speeding (82 km/h) on a very long, wide bridge near where I live. The speed limit there is 60km/h but everyone does 80 - 90 across that bridge (no excuse).

Folk are now telling me that I should contest the fine because speed determination by tripod-mounted camera equipment (probably on the approach to the bridge) is not valid because a bridge is a “moving structure”. I must say that I have noticed that there is discernable vibration on a bridge when a heavy vehicle goes past.

I am not terribly fussed about this, regarding the occasional speeding fine (R400) as part of the cost of running a motor car, like toll roads and punctures.
But as a matter of interest could I ask, Duncan and Eugene (Engineering and Law), and any others; do you have an opinion on this? Would the vibration on a bridge be sufficient to invalidate the speed determination, or is this more in the nature of an urban legend?

[Dave A]

I seem to recall there was a jurisdiction issue around bridges, but that could easily be another urban legend.

The other point that rings a bell was that the measuring device could not be mounted on a bridge - due to that same vibration issue you mentioned.

(Definitely not legal advice - just stuff I've heard along the way).

[duncan drennan]

The movement of the bridge must influence the measurement somehow, but I can't even guess to what extent (I imagine unnoticeable, but I could be wrong). There must be some sort of manual which says that speed measurements are only allowed under such and such conditions, and logs must be kept and so on. Not sure where to get a copy of that though...

[Eugene]

When I was employed by the Department of Justice as prosecutor (many moons ago) I can recall a circular from the Attorney General (nowadays the Director of Public Prosecutions) that they were not allowed to affix the tripod on a bridge or even the window of the patrol car which quite often happened. If they hace changed the ruling, I don't know, but will try and find out and let you know.

[Eugene]

I found this interesting piece of info regarding the general conditions for prosecution with regard to speed measurements:

http://www.speedtraps.co.za/docs/Guidelines_regarding_laser_speed_measurement.pdf

[Graeme]

Eugene - thanks for your trouble. Do you know who issued the document?

Kind regards, Graeme.

[Eugene]

No idea - I see it is marked anonymous, but it bears a familiar resemblence to the prosecutor notes I have.... suppose they are not meant to be public knowledge.

[Brainwaves]

While you are on the topic, did you notice on the highways there are an 80km board on account of road works near almost all of the cameras, and no road works for days? But when you get your ticket you apparently drove 100km on an 80km speed zone.... On the highway?!!!!

[Dave A]

About the best way to get tail-ended on a freeway is to drive at 80kmph on those sections.

Scary.