WHO, WHAT, WHY?
The Magazine answers...
When motorists brave snowy roads, chances are that the gritter lorries have got there first. So how do their drivers get to work?
It's been a busy night
Getting about when it snows requires more than gritty determination. When motorists start their journey on a snowy morning, they have to defrost locks and clear windows.
But if the white world is working to plan, someone else has already cleared the road ahead. It is not always the case - as anyone who has struggled in today, or failed to make it altogether, can testify.
On Thursday, drivers in some areas were warned not to travel unless absolutely necessary, and treacherous conditions disrupted journeys. Few motorists will have forgotten the sight of thousands of drivers stranded on ungritted roads after heavy snow fell in January 2003 - some were stuck on a frozen M11 between London and Cambridge for up to 20 hours.
The theory goes that those charged with gritting and clearing routes set forth first - so how do they get there?
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For the motorways and major A roads in England, they come from the Highways Agency. Elsewhere, the major routes fall to Traffic Wales, Transport Scotland and Roads Service in Northern Ireland. In local areas, the lesser A and B roads are left to local council contractors to cover.
The Highways Agency alone sends out 400 winter service vehicles, or gritters. With a giant blade fitted, 300 of these can be deployed as snowploughs. The agency also uses a handful of "snow blowers" - massive vacuum-like machines that suck up the snow and blow it elsewhere.
How many people called into work depends, of course, on the weather. And how much grit is used from the 5,000 tonne salt barns that dot the roadside is likewise adjusted, depending on the temperature. One spreader can take 11.25 tonnes over a maximum of 50 miles along a three-lane motorway.
Each vehicle has one operative, who drives and spreads grit. With one eye on local weather forecast updates, the secret is to call them in before the snow hits, says Iain Semple, of the Highways Agency. Drivers are at the depot before the snow starts and the agency's pre-mapped adverse weather routes are gritted in advance.
Three teams of workers cover 12-hour shifts. If the drivers can go home at the end, they do. But if more bad weather is forecast, they are called back in to the one of the 152 roadside depots and sleep and eat there.
Called in before Thursday's snows
Accommodation is basic - food and a bed, of sorts. "It's not like being a fireman. It's emergency bedding, put up on camp beds, as we only do this once or twice a year."
Overnight, Great Malvern in Worcestershire saw the deepest snow recorded in the UK in this bout of weather at 9cm (3.5in). Spare a thought for the county council's 28 drivers, out on peaks like British Camp in West Malvern in freezing conditions.
"At midnight last night all the drivers were on the highest points throughout Worcestershire, waiting for the snow to flurry," says spokeswoman Jackie Alderson.
When the lorries are empty, they head back to the depot to refill with fresh salt and fresh staff. But with temperatures set to stay low all day - -3C to just above zero - and forecast to drop tonight, their drivers will tonight be bedding down in the makeshift surroundings of the depot.