Grit/salt lowest effective temp

[Ade B]

Having traversed the M1 & A50 twice in the last 24 hours, lowest temperature I saw was -12. From a quick google -10 is roughly the lowest effective temperature for grit to be effective. Certainly seemed plenty of grip at the time although a catastrophic slide was in the back of my mind every time I touched the brakes...

Anyone any thoughts?

Ade

 

[Spinal]

The freezing point of salt saturated water (i.e. the point where no more salt will dissolve) is -21.1C; so I reckon that unless there are additives, that's the point where salt will stop working.

The grit on the other hand, will still increase friction and provide some grip.

M.

 

[davidjpowell]

I saw -18 this morning. Roads were fine when gritted, but otherwise were a tad hairy in places...

 

[JOB-BLACK-RAT]

-18

Cripes and I though it was cold at -2!

 

[219]

- 9.5 when I went out at 2pm this afternoon with the sun shining in a cloudless sky !

 

[Satch]

You can see from the graphs that salt stops being effective as a practical measure at about -10C (15F in old money) because at that temperature it takes so damn long to do the job and is less effective in terms of the quantity of ice it will melt. At -18C (0F) it takes ages to do bugger all.

So when really cold need to use Calcium Chloride in the mix but that is more expensive and unless kept in airtight conditions absorbs moisture from air and turns into a lumpy sticky mess.

So in Alpine or Nordic conditions might try to add traction by putting grit down on tricky stretches (that also helps to break up ice pack as vehicles drive over the surface) but otherwise many places simply do not bother to try and clear down to to the road surface, so use of correct tyres with studs maybe.

If you look at the Nokian site you will see that do ranges of "Nordic" and "Central European" winter tyres to deal with hard packed snow and snow/slush/melty stuff respectively for that very reason

 

[DITTRICH]

-18 ? Try -32 that's the worst I endured in Moscow. Or going to the outdoor privy at sergeevka hunting lodge, Primorski krai, Russia in -26 . Or -20 and 100kph wind in Vostochny. I'll get my coat...
...and long johns, jumpers, coat and furry russian shapka.

 

[Spinal]

-18 ? Try -32 that's the worst I endured in Moscow. Or going to the outdoor privy at sergeevka hunting lodge, Primorski krai, Russia in -26 . Or -20 and 100kph wind in Vostochny. I'll get my coat...
...and long johns, jumpers, coat and furry russian shapka.

Or some Vodka... that'll warm the cockles without any of that girly stuff

 

[lancebond]

-18 ? Try -32 that's the worst I endured in Moscow.

if it had been in newcastle the lasses STILL wouldn't wear anything!

 

[flango]

As Grit is a bit of a loose term the real material spread on the roads is Rock Salt which is usually a by product of Potash Mining and the majority of UK stock are supplied from Cleveland Potash in the North East.

Rock salt is effective to -10 but in reality taking the time factor into account it is only really effective down to about -6

Most Nordic countries do not use any form of salt the main reason being it attracts the reindeer down onto the roads to lick the salt and then they cause more accidents than the snow it's self. You often see big salt blocks the size of barrels at the side of the roads in Scandinavia for that very reason so the deer can lick them and not venture onto the road.

Calcium Chloride solution is used heavily in the mining industry on internal haul roads and yes it works but boy you should see how it rots the chassis of those caterpillar trucks.

It's a difficult one to get right best option IMHO is plough the roads and fit winter tyres for the conditions.