Road Closure A378

Diversion routes; blue route >7.5t and/or >4.5m height. Click to enlarge

Closure site detail. Click to enlarge

Planned Resurfacing Works A378

Next month Somerset County Council and its highway service provider, Milestone, will be looking to carry out resurfacing works along the A378, known locally as One Mile Hill. Here is what Somerset West and Taunton (SWaT) Area Highways Office has told us.

A378 One Mile Hill Langport Road.

For several years SWaT Area Highways Office has carried out drainage improvements on this hill, as over time the below ground drainage system had become fractured and displaced causing water to flow through the sub structure leading to cracking and ground movement. The last drainage scheme was carried out in 2019 and movement seems to have slowed. So now the intention is to replace the damaged road surface with a new surface, whilst incorporating a geo-textile membrane within the layers of the carriageway to slow or prevent further movements of the sub-structure. Also during the scheme design it was considered the A378 carriageway within the South Somerset area was showing signs of deterioration, although not related to drainage, and the Asset Management team made the practical suggestion of continuing our scheme into South Somerset Area.

Timing of Works

8th – 12th August Daytime – Temporary traffic lights to carry out minor prep works along this section of carriageway, current belief is this should take only 2 – 3 days.

15th – 26th August 7:30 – 18:00 – Daytime closure to allow resurfacing of this carriageway and the installation of geo-textile membrane material. For several weeks discussions have been held with Street Works, Milestone, Asset Management, Area Highways Office and Comms about the suitability of a night time/evening closure, which would normally be the default, versus a daytime closure. However, for the following reasons it was decided to carry out the works in the daytime.

• Road edge through the wooded section of One Mile Hill drops off and there is a risk to workforce falling off the edge at night.
• Specialist engineering reason, rolling out and laying of Geo-textile membrane can be done at night, however daytime application is more favourable to ensure a quality finish.
• Potential clash of night time closure with National Highways on planned works on A303 and A38 Toneway.
• Daytime closure provides a shift of approximately 10.5 hours, evening shift provides approximately 5 hours, therefore doubling the duration of the scheme. With the daytime closure there is the potential to finish quicker.

For the two drainage schemes carried out in 2018/19 & 2019/20 a 24hr closures had to be implemented due to open cut trenches and whilst there was impact it was at a manageable level, hence all these schemes have been carried out in the school holidays.

NB In previous A378 road closures the potential for a high volume of traffic to use a narrow back lane off the A378 known as Rock Hill that emerges back onto the A378 at the top of One Mile Hill was noted. With the road closure on the 15th – 26th August this lane will be closed off as well for the purpose of traffic management and to save the residents seeing this route being used as an unofficial diversion route.

For more information on the diversion routes in place click here

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