This site uses cookies. For more information, please see our Privacy and Cookie Notice. If you don't agree to our use of cookies, please navigate away from this site now.

A77 Landslip Project to Begin

Published date : 15 Sep 2017

Scotland TranServ, on behalf of Transport Scotland will begin reinstatement works on the A77 Marchburn landslip north of Cairnryan.

In order to establish the working site and install supportive piling, it will be necessary to completely close this section of the A77 for the duration of the weekend beginning 8pm Friday 3rd until 6am Monday 6th November. 

The health and safety of our workers and the travelling public is of utmost importance to Scotland TranServ, and therefore the decision was taken to keep traffic in the centre of the road, safely distanced from both slopes.

Winter storms in November 2014 caused the failures on both sides of the A77 trunk road. This meant that the embankment supporting the carriageway was compromised, while the upslope embankment deposited debris directly onto the trunk road carriageway.

Temporary repairs were carried out in early 2015 to clear up the debris on the carriageway and backfill the upslope side with rockfill. However, no such short-term remediation was possible on the downslope side due to the size of the failure and the 40m (130 feet) high steep embankment between the road and Loch Ryan (see Fig 1 below). A careful geotechnical assessment of the area was required in order to determine a long-term solution to the issue.

Scotland TranServ is proposing to undertake works to fully reinstate the slopes beginning at the start of November 2017. We are currently in discussion with a number of utilities and other authorities in regard to the planning and management around these works.

Following the weekend closure to establish the working site, the existing traffic lights will be reinstated, providing our contractors with the required lane space from the flow of trunk road traffic to work as safely and efficiently as possible.

This is a large, complex project that we expect will take a number of months to complete. Our contractors therefore forecast that the traffic lights will be lifted, and the road fully reinstated early in 2018.

In order to maximise the traffic management during these works, we are proposing an additional resurfacing project for the A77 in this area. It is our intention to resurface 1km of the carriageway at Altimeg, approximately five miles south of Ballantrae.

Works will be carried out under the same weekend closure as is planned for our Cairnryan works.

You may have further questions on these intended projects, of which we hope we have answered the majority of your queries below

What caused the landslip?

Winter storms in November 2014 caused the failures on both sides of the A77 trunk road approximately two miles north of Cairnryan.  The embankment supporting the carriageway fell away, while the upslope embankment deposited debris directly onto the trunk road carriageway.

The health and safety of our workers and the travelling public is of utmost importance to Scotland TranServ, and therefore the decision was taken to keep traffic in the centre of the road, safely distanced from both slopes.

Why has this taken so long?

Temporary repairs were carried out in early 2015 to backfill the upslope side with rockfill.  However, no such short-term remediation was possible on the downslope side due to the size of the failure and the 40m (130 feet) high steep embankment between the road and Loch Ryan.  As well as being difficult to access, this meant that there is nothing at the bottom of the rockfill to hold it in place (see Fig 1).  A careful geotechnical assessment of the area was required in order to determine a long-term solution to the issue.

What is involved in repairing this slope?

The failed slope will be replaced with a retaining wall to support the carriageway.  The wall will be embedded into rock at the bottom, and pinned back with rock anchors at the top.  In order to establish the working site, it will be necessary to excavate to three metres below road level, then build back up upon completion of the wall.  During most of the works, one lane will remain open to traffic and this will be supported above the working site with temporary sheet piles.  Unfortunately, to install these temporary sheet piles, a total road closure will be required.  Upon completion of the works, the temporary sheet piles will be abandoned in place, rather than disrupt the travelling public again by closing the road to remove them.

Why is a road closure necessary?

The reinstatement works will require excavating the northbound lane to three metres below the existing road level. Supportive piling is required allow the southbound lane to remain open, as it is at present, during the remainder of the works.  Installing these supportive piles requires placing a large pilling rig in the southbound lane, where it can lift and manoeuvre the piles into position, and drive them home.  Therefore, it will be necessary to completely close this section of the A77 for the duration of a weekend.

Transport
Sign up for our newsletter
Connect
  • Facebook
  • Twitter
  • Email
Share

Please click the link below to register to vote in future UK and Scottish General elections.

The costs of this website have been met by Parliamentary resources.
Complaints about website content should be sent by
email to sp.info@parliament.scot

Contact
Name
Email
Phone
Message
To comply with data protection regulations (2018), we are unable to store and use your information unless you give us your permission. Please select Yes to allow this. View our data protection policy for details.
© 2018 Jeane Freeman MSP | All Rights Reserved