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A23 Widening: A winter's tale

The A23 widening works between Handcross Hill and Warninglid aim to make the crucial London to Brighton road safer and more efficient by adding an extra lane on both sides of a perilous 3.8km stretch. The challenge that contractor Carillion has faced in bringing this project to life has been how to do this while remaining environmentally sensitive and minimise delays to the traffic and the project.

The project looked doomed almost before work had begun last year after heavy rainfall held up earthworks.

“Earthworks are key in the early stages,” says Carillion project manager John McNiffe. “Once you’re on stone you can do anything, but when you’re still in the muck and the mud it can be very difficult.”


Wider view: The work will add extra lanes at a key A23 pinch point

Instead of falling behind, the team embraced the challenge and brought in a number of innovative measures to keep the project on schedule. One was the use of complete machine automation to lay down concrete access roads. When building access roads for houses and businesses just off the A23, the team used a concrete paver which “exudes” fibre reinforced concrete from the back as it moves. The machine is operated by remote control and GPS to minimise the need for manual handling. While the concrete still needs joints, it has no need for reinforcement or a capping layer below the sub base.

“This was a decision that came from the bad weather,” says Mc- Niffe. “I don’t know of any other team that has used it before. We’re now looking at other possibilitiesfor automation, such as blacktopping.”

“We used a granular stone to allow ground work to continue through the winter”

John McNiffe, Carillion

Another innovative approach came in the construction of a parallel service road for local traffic to reduce the risk of accidents around businesses along the A23.

“We used a granular stone to allow ground work to continue through the winter,” said McNiffe. “It’s now ready for surfacing. We’re still hitting our key milestones.”

The next key event will be the opening of the Warninglid roundabout at the end of April. The roundabout itself still requires a final layer of blacktop, as well as signs, footpaths and other finishing touches. But once open it will improve access to the A23 and provide more flexibility contraflows , a crucial aspect of the project.

“The whole job is based around key traffic switches [contraflows],” explains McNiffe. “To make the job work we are using lots of switching and contraflows to minimise impact on traffic.”

Aside from minimising the effect on traffic, the project is already improving the safety of the road. The introduction of speed cameras has had a huge effect on driver behaviour, with the number of people prosecuted for speeding on the road dropping from 260 per week, when work started, to 185 last week.

“We’ve seen driver behaviour change totally since we arrived,” says Highways Agency project leader Chris Bacon.

Another crucial aspect of the project has been environmental impact. The A23 runs through picturesque countryside and the project involved cutting down ancient woodland owned by the National Trust.

“We’ve taken a field alongside the site as mitigation and moved the soil across,” says Carillion senior engineer Martin Dobby. Trees will be planted in the field to compensate for those lost to the road widening.

“We’ve also added two water treatment areas for run-off. And we paid a local landowner to maintain the improvements we are making after we finish.”

Environmental measures weren’t kept solely to soil, however; trees had to be removed in stages to avoid disturbing dormice. The animals live in the trees during the summer and hibernate in the stumps during the winter.

“We had to remove the trees while they slept, then wait until they woke up before we could come back and remove the stumps,” explains Dobby.

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