Posted 1 day ago

Are lorries immune to speed cameras?

As the title.
Are lorries immune to / don't speed cameras work on them?

For example, I drive along the M1 near Meadowhall, and there's a 50mph speed limit in place for about 9.5 miles whilst no-one works on some laybys.

I always stick to the signed 50mph limit yet every single lorry overtakes me, day or night, at 60mph? Same with highway maintenance vehicles.

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2nd May
Probably 56mph. General rule of thumb is 10%+2 until you start getting flashed/fined. So a 50mph limit would allow up to 57mph. Your speedo will generally under read too. So 50mph on speedo could be 47mph.

I cruise on a GPS indicated 54mph.
2nd May
Here is a list of the tolerance which varies from force area to force area in a particularly unhelpful way.
confused.com/car…ces
2nd May
An average car needs to have a speedo that can read up to 10% higher but no lower than the actual speed. So in most cases they're set high 'just in case'. Mine is very similar to Gj9382, a GPS 50 reads as 54mph on the speedo.

However lorry speedos have to be spot on, and recalibrated every couple of years. They will most likely be doing the actual 50mph.

(Edit: yes, as several people have commented I had it the wrong way round!) (edited)
2nd May
At 70mph on my GPS my speedo reads 73.
And as you allude to almost a side effect of what used to be called tachos is very accurate recording of speeds on lorries and even more so on buses in a way.
(I have professional experience of examination of such things).
2nd May
As others are suggesting, it’s a mixture of your car having an optimistic speedometer while the HGV has an accurate one. And potentially the HGV driver pushing it with an extra mph or two on top since they know that the speed cameras have a slight bit of tolerance on them.

In my car, I know that I have to do an indicated 76 to be doing a GPS confirmed 70. And I’m also told by others who own the same car that I could do an indicated 80 and still not get flashed by motorway speed cameras due to the tolerance.

In a 50mph zone with average speed cameras, I’d have to do an indicated 54-55 to keep up with the flow of traffic like the HGVs.
2nd May
I had the same problem while driving to Gatwick on a very early, VERY wet morning. DHL truck come from the inside to the 3rd lane (not allowed anyway) when I was doing 50 in the middle overtaking (or at least pacing) another truck on the inside. I would not have been bothered except that the lanes were very narow and he pulled into my lane straight away forcing me to pull up sharply.

Never seen this before, but it seems to be more comon than thought.
2nd May
IIRC HGVs have tachometers that record the speed and start/stop of the driver. It's unlikely that they would risk going over any speed limits as it would be recorded regardless of any speed cameras! (edited)
2nd May
I do 56 cruise control in the 50 zones and 67 in 60s, never received a ticket.
Your speedo already over readsby around 5% and you can go just over 10% over the speed limit before the cameras trigger
52 s ago
More of an issue is obnoxious lorry drivers tailgating through roadworks within millimetres of the car in front - dangerously leaving absolutely no stopping distance. I would love to see the police starting to issue fines for that kind of selfish wreckless behaviour.