Gritting lorries

[marctwo]

Driving back lastnight turning off the M1 onto the M25. On the sliproad I encounter a gritting truck doing 40-50. The slip road is 2 lanes and he is in the inside lane. Dilemma. Do I pass the truck as quickly as possible to minimise the time exposed to the grit shower, or do I crawl past as slowly as possible to reduce the speed differential? I opted for the former but it really hurt to hear all those stones crashing against the car. Could not face looking at it when I got home so don't know what the damage is like.



>> Edited by marctwo on Monday 30th January 12:13

[Parrot of Doom]

Drive past it faster, it reduces the exposure and minimises the speed differential.

[minimax]

I had this problem last night too on the M1 slip road on to the M25...but since i'm in a company car I didn't give it a second thought and floored it on to the M25

[marctwo]

Parrot of Doom said:

Drive past it faster, it reduces the exposure and minimises the speed differential.

How can it do both???

[Parrot of Doom]

Laws of motion.

[TonyHetherington]

eh?!

surely you want to maximise the speed differential; i.e, you want to be doing a hell of a lot more speed than the gritter lorry? (which is what would happen if you sped up?!)

[Flat in Fifth]

Nah you wait until the next junction, see if the gritter is going up the slip road, if so all is well.

If not take exit slip and ..... test your vehicle capabilities up the off slip, round the island and back down the on slip.

Tis an interesting challenge when the gritter is doing about 50.

[NickD]

TonyHetherington said:

eh?! surely you want to maximise the speed differential; i.e, you want to be doing a hell of a lot more speed than the gritter lorry? (which is what would happen if you sped up?!)

Surely not.

Surely you want to drive as slowly past the gritter as you stomach so that the the grit is hitting the car with less relative speed than if you sped past the gritter.

[monkeyhanger]

If it's a motorway and reasonably quiet, i zip off up a slip-road and re-join in front of the gritter on the other side

[marctwo]

monkeyhanger said:

If it's a motorway and reasonably quiet, i zip off up a slip-road and re-join in front of the gritter on the other side

Good plan, apart from the fact I was ON a sliproad when it happened!

[rob.e]

Flat in Fifth said:

Nah you wait until the next junction, see if the gritter is going up the slip road, if so all is well. If not take exit slip and ..... test your vehicle capabilities up the off slip, round the island and back down the on slip. Tis an interesting challenge when the gritter is doing about 50.

So, you're advocating driving as fast as you can around a (potentially) ungritted roundabout in icy conditions..

[Parrot of Doom]

TonyHetherington said:

eh?! surely you want to maximise the speed differential; i.e, you want to be doing a hell of a lot more speed than the gritter lorry? (which is what would happen if you sped up?!)

No. If you did that, you risk more damage to your car.

When the grit drops out the back of the lorry, its not doing 0mph. Its not doing -50mph. Its doing roughly the same speed as the lorry.

Therefore if you drive past the lorry as fast as practical, you both minimise the exposure to the grit in time, and you also lower the speed at which the grit hits your car.

Look at it this way - if the gritter is coming the other way, how fast is the grit moving? It doesn't fly away from you now does it?

[dazren]

You hold back and overtake the gritter, with maxixmum distance when on the M25.

DAZ

[Flat in Fifth]

rob.e said:

Flat in Fifth said: Nah you wait until the next junction, see if the gritter is going up the slip road, if so all is well. If not take exit slip and ..... test your vehicle capabilities up the off slip, round the island and back down the on slip. Tis an interesting challenge when the gritter is doing about 50. So, you're advocating driving as fast as you can around a (potentially) ungritted roundabout in icy conditions..

No but to do it with best possible progress consistent with the ACTUAL conditions.