The signs of roadworks frustration are clearly evident. One motorist, being “convoyed” through an ongoing surface-dressing programme near Pulverbatch, expresses his boredom by slaloming behind the convoy car like an F1 driver held up by a safety car.

It’s the middle of summer – the furthest point from the bleak midwinter’s best efforts to wreak havoc on Shropshire’s road surfaces – and the war on potholes continues apace.

“It is the season for road surface dressing,” says Gary Rogers, head of highways for Shropshire Council. “It’s a big tool in our box for preserving the county road network.

“Potholes are a big issue in winter and we repair these, but in the summer the surface dressing seals the road and stops water getting into the structure of the road, which protects it against potholes breaking out.”

Highways manager Gary Rogers, left, with Darren Jones, national surface treatment manager for Enterprise

By way of analogy, he adds: “It’s a bit like painting your fence with creosote.”

The window of opportunity for surface dressing – tar and chipping – is April to September.

Anyone driving along the county’s highway and byways right now will have seen a proliferation of triangular roadside signs that warn of skid risks and loose chippings, urging drivers to stick to 20mph.

They will know that up ahead stands a man with a stop-go sign, and that possibly a convoy car will ferry them at a snail’s pace through a “train” of bitumen sprayers and chipping spreaders.

Oh, the very inconvenience of it all! But not half as inconvenient as having roads littered with potholes or enduring the tribulations of having the road to work ripped up for a week.

Darren Jones, national surface treatment manager for Shropshire Council contractors Enterprise, says: “It is actually a very cost-effective way of maintaining a road. It costs £2 a square metre as opposed to £13 a square metre for resurfacing, and it is very effective in keeping the road sound.”

In Shropshire, this summer’s work covers about 1.2 million square metres of road, or about 240 kilometres of straight highway, at a rough cost of £2.2 million.

In Telford & Wrekin where a similar programme is ongoing, 200,000 square metres of road are being dressed, or the equivalent of 40 kilometres of road network, costing about £400,000.

“In the current economic climate, we need to do cost-effective work that does the job,” says Darren.

Gary adds: “Most people understand the importance of these works but some people do ask ‘Why are you putting surface dressing down when there’s nothing wrong with the road?’

“But what they don’t see are the tiny signs of surface deterioration that might break out into a pothole next winter. But if we do it now it won’t break out.

“You probably won’t get potholes for three or four years, but maybe up to 10 years.”

Phil Coulson, supervisor for the Shrewsbury surface dressing crew

The Shropshire Star reported this year on a campaign to bring pothole warning signs to roadsides most affected by the blight.

Gary reckons the money would be better spent on maintenance. “By surface dressing you are addressing the problems of potholes.

“We are aiming to repair the road and potholes using all the techniques available to us, not put up signs.

“I would rather put up temporary road signs, if I had to, rather than have pothole signs.”

As the Shrewsbury highways team drives its surface dressing train down through Hook-a-Gate and Pulverbatch and down towards Bishop’s Castle, it is surprising to see how quickly the dressing job gets done.

It is an incredibly well-oiled machine. A moment of apparent inertia while the crew waits for a sweeper to come and dust away loose debris is followed by a dozen or so high-visibility men swinging into action, driving the train south at a speed of about 7mph.

The technique also restores skidding resistance as well as sealing the road surface to prevent water ingress. Hot bitumen is sprayed onto the road and chippings are then applied and rolled in. The road is then swept to remove excessive chippings.

There is a reason, too, why motorists are asked to drive slowly through newly-dressed stretches of road. Twenty miles per hour is the ideal speed for passing cars to help embed the chippings, while at this speed no damage is done to either the fresh surface of the highway or to cars and passers-by.

But some motorists’ driving habits do leave something to be desired.

“There’s one car not doing 20mph,” says Darren, observing a 4×4 coming out of Pulverbatch doing at least double that.

“But this stretch has been done only this morning and you can see how it’s already embedding will – that’s 8,000 square metres done before lunch.”

Phil Coulson, maintenance crew supervisor on the job here, is also working as the convoy driver. Road dressing is a dangerous job enough without motorists hurtling past at uncontrolled speeds.

And the potential dangers sometimes go beyond the job in hand.

“Drivers get frustrated,” says Phil. “I’m the same if I’m going on holiday and I get stuck in a traffic jam.

“The lads do sometimes get a bit of grief from members of the public. Ninety-five per cent of people are fine but you do get the odd one or two who ask ‘why are you doing this’.

“If they have been waiting for six or seven minutes for the traffic to go, for instance, what they want to do as soon as you let them go is speed off, but it’s the worst thing they can do because this can ruin the dressing and you have got to do that bit again.”

By Ben Bentley