Earlier this month, the Gloucestershire Warwickshire Railway met with its consulting engineers and the loss adjusters for our insurers, Travelers.  As a result, a final plan has been developed for the embankment repairs and work is about to start.

The project to rebuild the collapsed embankment, led by properties director Darren Fairley, has been divided into seven separate work packages appropriate to the movement and damage found, and improved site drainage. Click here for an diagram and explanation of the seven sections of work. The embankment will stabilised and rebuilt using a blend of design options between soil 'nailing' the less damaged sections of the embankment and securing them for the long term, and fully digging out and rebuilding where damage is most severe. 

Design of the work is almost complete.  The railway's consulting engineers, David Symonds Associates (the company that advised on the Severn Valley Railway's devastating slips and our previous repair to the Cheltenham Racecourse embankment) can now provide a reasonably accurate indication of costs.

Drainage work starts now

Explains Malcolm Temple, chairman of GWSR Plc: "I'm delighted that we have now negotiated access rights to the embankment with the owner of the adjoining land.  This will enable the heavy plant and equipment to be used as well as the materials to be used, to easily reach the site.

"In addition, tenders have been received for the new drainage system on the Cotswold side of the line, which will better intercept water coming off the hills than the original 1903 design which has shown with dramatic effect to be no longer adequate.  New drains on both sides of the line (Malvern side being incorporated with the main collapse repair), will direct the flow more efficiently to two existing GWR-built culverts.  We now believe BR struggled with this location, particularly just before closure of the railway. But since then, the problems have laid dormant - until now. 

"I'm glad to say that the winning tender for this work is lower than the original budget and the contract has been placed for this first stage of the work.  Contractors should starting this work by the end of the month.

"Tenders have also been received for the soil nailing*.  This is a modern technique that, as its name suggests, comprises huge 'nails' that reinforce the strength of the embankment.  The nails extend right into the underlying ground to secure the embankment slope by stopping further slippage and coming under tension as they slightly bend"

Analysis of the considerable amount of slag and locomotive ash that has been used for past repairs now appears not to be contaminated or toxic as first thought.  The ash, together with unstable soil, will be excavated and the railway has received tenders for this work.  The final contract sum will be negotiated as soon as the design work is finalised and that is expected to take place soon. 

Budget

In cost terms some real savings have been made from the original £1.1 million cost estimate, as Malcolm explains.  "This is partly because the ash fill doesn't appear to be contaminated which would have brought a significant additional cost for its safe disposal.  Although final detailed costings have yet to be concluded, we are confident that the total bill won't exceed £900,000. That's still an enormous sum, and it leaves at least £400,000 to be found over and above the expected insurance claim settlement.

"Although different contractors will be involved in the separate elements of the work, these have been taken together for cost purposes and I'm delighted to say that the Board has authorised the main work to start from 1 October, after the essential drainage work has finished.

"However, it is important to point out that funds must flow in now, to ensure that the once the work starts, it will continue through to completion.  If we run out of money, then the work will have to be suspended until the finance is available.  If the cash is available, the work is likely to be completed by May 2011 - and again, this is earlier than some estimates have suggested."

The railway is about to start a major £1 million fund-raising initiative.  But if the cost is less than estimated, why so much?

Malcolm explains: "One of the really attractive features of our railway is that we have several miles of embankment that are in some cases, very high.  This allows for some of the finest countryside views that you can see anywhere from a carriage window and it is a bonus for railway photographers too, as pictures in the railway press regularly show.

"The Board is very conscious that the collapse of the embankment at Gotherington is a call to action for some other locations.  Once the contractors have completed the drainage work at Gotherington, they will immediately focus on new drainage at Far Stanley.  Work during the 'close' season will also be carried out at the so-called 'Chicken Curve' on the Toddington side of Winchcombe station.  The work includes reduction of the depth and weight of ballast at this point."

Chicken Curve is a name given by railway volunteers because there was a chicken farm adjacent to the curve (the old chicken sheds are still there).  It's definitely not because of any thought of 'running the gauntlet' on any past track or embankment issues!

Adds Malcolm, "the additional emergency funds will allow us to ensure that the rest of our infrastructure is secure for future generations to enjoy."

Malcolm also points out that discussions are taking place with the insurers for compensation for lost income and other costs.  "Our passenger figures have held up well because of the huge appeal of the GWR175 event - but because of the embankment collapse our ordinary, day-to-day passenger traffic is about 25 per cent down compared with last year.  That coincides almost exactly with the usual takings at Cheltenham Racecourse station.  If this claim is successful, it should ensure that there is no impact on the profit & loss account from the collapse."

Forging north

Malcolm says that the aim has been to ensure that the embankment collapse at Gotherington doesn't affect the railway's overall expansion programme.  "I'm delighted to say that the temporary hold on the Laverton extension has been lifted by the Board.  The Permanent Way team has now been asked to proceed as quickly as they can towards completing this part of the project.  Most of the track is in place now and the team will press ahead with the final work, including ballasting and installation of a run-round loop.

"The plan is to have this work completed in time for next season with trains running to Laverton loop from March 2011."

* What is soil nailing? It is a technique developed in France in the 1970s and is now widely used throughout the world for civil engineering projects.  It has proven to be an extremely effective way of stabilising and increasing the shear strength of soil slopes such as cuttings, embankments and retaining walls.  Holes are drilled and slender threaded bars inserted, usually with expanding 'plugs' that lock the bar into the surrounding soil. The bore surrounding the rod is then grouted which prevents corrosion and a large nuts are used to secure the bars against large plates (or 'nail heads') on the slope surface which tie in to geotechnical reinforcing grids where appropriate to complete the repair.  These are easily confused with, but not the same as, anchors which are grouted up hard and tight and tie sections of rock etc. together where they have become unstable.