Putting right a defect on the six-year-old A38 Dobwalls bypass will cost £10.6m – and will mean the dual carriageway is reduced to one lane in each direction for several months. Preparatory work is due to start later this month on what the Highways Agency describes as a 'safety scheme' aimed at reducing the number of lane closures on the route. Since the bypass was completed in 2008 at a cost of £53m, problems with surface water have developed leading to lane closures during cold weather due to the risk of ice forming. Investigations into the causes have been ongoing and as a result the agency will now be reconstructing just under a one-mile section. Project manager Stephen Coe said: 'It's not acceptable that we have to close off a lane each winter because of the build-up of water and ice, so we will reconstruct this section to rectify this. 'We are working with Cornwall Council and our contractors to minimise disruption. We aim to complete the scheme before the summer season.' During the reconstruction, the agency plans to identify the causes of the problem and install extra drainage. Site preparation work will begin on September 22 with construction work starting in October. During the main work, traffic will be put into a contraflow on one carriageway meaning single lane traffic in each direction.