Monday, 28 September 2009


So there I was, heading up the M5. It was 6:30 pm and getting dark. 300, 400metres ahead was an HGV. Not content with the rear lights the manufacturers of the truck had fitted some hero, I assume the driver, had fitted a few extra lights. Across the top at the back there were 10 red lights, down each side were 15 extra lights. That's 15 on each side. 40 extra lights in all. It stood out, the fact that I could pick it out on a crowded motorway 3 or 4 hundred metres away shows how bright this thing was. Maybe someone drove in to the back of this guys truck one day and said, "Sorry mate. Just didn't see you."

When I caught up with him I noticed there were even more lights along the side of the truck, paranoia in a big way. Finally I got past him and he flashed his lights to say it was safe to move back into the left lane. Bright? Well yes. The possibility the Gloucester had just been destroyed by a thermonuclear device crossed my mind for a moment.

There may be a HGV driver out there who can answer a question. Nothing to do with lights but overtaking. Please can you tell me which HGV driving school teaches it's pupils to slow down when overtaking. There was one today, first HGV doing 50mph, second HGV doing 58mph, me doing 60mph. second HGV pulls out and I slow down to 58. Then 2nd HGV slows to 50.01 mph as it goes past the 1st HGV. Are the drivers having a conversation or what? There must be a logical reason but what it is is beyond me.

Disclaimer: This HGV is not the one with all the lights, nor does it slow down and have a conversation with the HGV it is overtaking. Not as far as I know anyway.

It's just the first photo of an HGV I came across in my library.


Anonymous said...

Slow down due to slipstream and then bow wave effect. The truck doing 58 is probably only capable of doing 56 until he gets into the slipstream of the guy in front. Do you notice any reduction in speed when he pulls out?

Then when the overtaker get almost level with the slower truck he hits the bow wave. It may not be visible, but it is there. Overtaking truck may not have sufficient power available to maintain speed when breaking through the bow wave.

See if you (or your autopilot) need to depress the gas pedal when you get to the same position.

Lord Hutton said...

I was about to say what Anonymous said. It's the slipstreaming. Just a pity they always try it on hills.

Jon said...

I've noticed that many, many people in cars slow down to pass. I don't think slipstreaming has anything to do with it.