‘Keyhole surgery for roads’ cuts disruption

THEY are one of the biggest bugbears of modern life – roadworks that cause long ­delays, frustration and anger.

Scottish Gas engineers carrying out the innovative technique. Picture: Contributed

But now the misery for ­drivers is being eased with a revolutionary “keyhole surgery” technique that has dramatically speeded up repairs.

Work that previously took three days is being completed within a few hours by drilling a small hole in the road rather than a large trench.

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The novel approach is being pioneered in Glasgow but is expected to be in use across the country by the end of the year. Scotland’s official roadworks watchdog body has welcomed the move as significantly cutting the length of disruptive repairs.

The method has undergone a two-year trial by the distribution firm Scotland Gas Networks (SGN), which has successfully used the technique to fix gas leaks in underground pipes.

Such incidents, which account for 80 per cent of its repairs, are the most disruptive to traffic as they are unplanned but the company also hopes to use the technique for other work, such as replacing gas mains.

The keyhole method could also be used by water and electricity firms and by roads authorities to repair potholes.

It enables traffic delays to be further reduced by using manhole-like metal covers to plug excavated sites during longer repairs so roads can be re-opened overnight or when no work is taking place.

The repair technique, known as “core and vac”, involves a machine drilling a two-foot dia­meter circular “core” in the road surface, which is lifted out and put back after the work is completed. The hole is excavated by blasting air to break up the ground before it is sucked up by an industrial vacuum.

Workers at street level using special long-handled tools then drill into the pipe – which can be up to seven feet below the surface – and inject a sealant to stop gas escaping.

The excavated material is used to fill in the hole and the core is then fixed back in place with a bonding agent, which sets in under an hour.

Such circular holes have been found to be less prone to cracking after being resealed than traditional roadworks.

SGN described the traditional method, which takes several days, of digging a trench, repairing the fault and bringing in new material to fill the hole as “outdated, time-consuming and inefficient”. Innovation and new technology manager Gus McIntosh said: “The quicker we can get into roads, get out of roads and get them reinstated and the traffic moving again the better for everyone – and that’s exactly what core and vac delivers.”

The company hopes that now Glasgow Council has approved the technique for use, other local authorities across Scotland will follow suit before winter, when gas leak incidents normally increase due to the effect of cold weather and higher gas pressure in pipes because of greater demand.

The Scottish road works commissioner, appointed to improve roadworks, said she would like to see the technique used more widely.

Elspeth King said: “I regularly remind organisations about the importance of reducing the time taken to carry out works to keep disruption to a minimum.

“I want to encourage any new ways of working which can minimise disruption. One innovation which I am giving my support to is that of keyhole technology.

“Use of SGN’s core and vac technique can reduce the time taken for a repair from three to five days to five hours. This has a significant impact on reduced road congestion and inconvenience to other road users.

“I consider that this technique will have a significant impact on the time taken to carry out gas mains repairs and look forward to seeing its use increase in Scotland.”

Motoring groups gave the innovation a cautious welcome. Neil Greig, policy and research director of the Institute of Advanced Motorists, said: “This looks like an excellent example of technology being applied to reduce delays to drivers and improve the quality of reinstatements.

“The proof will only come in the long term, however, and to date the utility companies have a mixed record on the standard of their repairs, which often leads to big bills for councils to remedy their failures.

“In ideal conditions I see no reason why this should not work, but on our streets which are already littered with potholes, trenches and patches it may be a different story altogether.”

A spokesman for Scottish Water said: “If there is damage to a road caused by a burst water main, it is generally more widespread than is the case with other utilities who encounter problems under roads.

“However, we will look at this technology to see if we can find a suitable use for it in the future.”

Twitter: @AlastairDalton