Holding back the flood!

As you will be aware, 2012 was the second wettest year on record for the UK as a whole and, in England alone, it was the wettest year ever recorded. So it’s been a good year for the ducks, but for many people, including railway engineers, it has been a nightmare – especially in the south west. The last couple of months have been particularly challenging.

To find out more, the rail engineer spoke with Steve Hawkins, infrastructure maintenance delivery manager for Network Rail. Steve is based in Plymouth and, with a supporting workforce of over 300, he is responsible for the ‘Safety of The Line’ in Cornwall, Devon and parts of Somerset. Speaking early in January, he recalled how his team had coped with the challenges created by the monsoon rains that fell over the Christmas period.

Saturated ground

Rain had been falling consistently throughout the year, and Steve explained that they had already had to deal with a number of local flooding problems. However, by November 2012, the ground was saturated and the Met Office was issuing severe flood warnings on a regular basis throughout the area.

One of the locations that Network Rail was very concerned about was Cowley Bridge junction which is on the approach to Exeter from Taunton. The river Exe runs alongside the railway and passes under the branch line to Barnstable. When the river floods, water covers the fields either side of the junction leaving the railway formation stranded in the middle, surrounded by water. A large culvert, approximately 2 x 3 metres in section, normally carries excess water away from the site but, on 22 November, the volume of water in the river was so great that it lapped over the tracks, destabilised the formation and washed away the track ballast.

This is a location that is very vulnerable to flooding, and there was a similar incident about twelve years ago when ballast was washed away. However, this time the volume of water was far greater and not only did the water submerge the junction but it then proceeded down the tracks in the direction of Exeter station, flooding a relay room and fourteen trackside location cabinets, causing significant damage to the signalling equipment therein.

Assistant signalling engineer David Gill helped bring together a highly skilled team of more than thirty engineers from within Network Rail, McGinley and Signal Construction. This team worked round the clock testing circuits, replacing damaged S&T equipment and replacing about two miles of cables. According to Steve, it was a heroic effort from the signalling team and their permanent way colleagues whose work to restore the track by importing new ballast, stabilising the formation and realigning and consolidating the track ensured that the route was reopened three days later. The signalling, however, would take another two weeks.

Welcome hospitality

Alongside the junction is the Cowley Bridge Inn which was also flooded – not for the first time. The landlord cannot get the pub insured, but he was able to provide hot food, a roaring fire and shelter from the rain. Wellies were needed, even inside the pub, but the landlord’s good natured, friendly 24-hour service was invaluable and made all the difference over both the first challenging three days and the weeks to come.

Four days after the line was reopened in November, with the rain still coming down, Cowley Bridge flooded again. The track was once more washed out and all the signalling systems, which were still being worked on, were all under water again, as were the Looe, Newquay, Barnstaple and Heathfield lines. It was back to square one.

With the help of Infrastructure Projects and various contractors, the tracks were repaired again. The line at Cowley Bridge reopened after three days but with no signalling – this would take another three weeks of 24-hour working with the assistance of maintenance and project staff from across the country. During this period, the Network Rail operations team and the train and freight operators also had a challenging time, running a service without any signalling.

The hope was that Mother Nature would be kind and give everyone a chance to dry out and recover from this experience. No chance! There was a record to break and the year was coming to an end. Meteorological forecasts were ominous, rain continued to fall and, four weeks after the line was reopened, new flood warnings were issued. There was a great risk that all the good work would be wasted which clearly would be unacceptable given the additional disruption that this would cause. Something had to be done to ensure that the signalling equipment would be protected, but what should that be?

Great idea!

Steve suggested to his team that they should sacrifice the track and remove a section of it before the flood water arrived at Cowley Bridge to save the signalling systems. This was unchartered territory and Steve explained that it was time to consider and evaluate any and all ideas that were being proposed. During this process, assistant track maintenance engineer Craig Hocking proposed erecting a dam across the track between the junction and the signalling relay room instead of removing a section of track.

Craig suggested that the dam could be a flexible structure filled with water. After searching on the internet to see whether there was such a service available, the team came across a company which specialises in finding solutions to water-based problems. Additional good news was that they had three tubular cofferdams, similar to the ones envisaged by Craig, available in their warehouse in the Midlands. They were dispatched to site immediately.

So far so good, but the Met office changed the flooding prediction time. It was now only about ten hours before the floods were expected. The team needed pumps to fill the cofferdams with water but, as one might expect, all such available pumps had been hired out. More quick thinking was needed, this time from signalling telecom maintenance engineer John Tancock who suggested that they contact the fire brigade.

This they did and, by midnight with three hours to go, there were four tenders, a lighting tender, a control unit and 20 willing firemen on site pumping water into the cofferdams which had now arrived. Two of the dams were ready and in place, 80 metres from the relay room, by 02:45. Before long, the dams were holding back a metre head of water. Twenty four hours later, the third dam was ready and positioned as back up behind the front two, in case one failed. Sure enough, one did – so the last line of defence worked and saved the day.

It is the first time that this type of protection has been used and Steve is now developing a business case to purchase the appropriate equipment in case there is another attempt to break the rainfall record in the future. This is very likely given the forecasts from the Met Office about possible future rainfall patterns and intensity.

Not to be outdone

Dealing with all this flooding was probably enough to keep any sane railway engineer busy over a Christmas holiday, but in this case it was not the whole story. The cliffs behind the sea wall at Teignmouth were clearly determined not to be outdone by Cowley Bridge and, on 27 November, there was a landslip with 1000 tonnes of material cascading down the cliff toward the main line railway. Fortunately, it fell in the cess and behind the fence that runs parallel with the tracks.

The fencing did its job of catching the landslip but it was badly damaged in the process. Only six hours after the start of the flooding at Cowley Bridge in December, another 1000 tonnes of rock and rubble came down, this time completely wiping out about twenty metres of fence and spilling onto the tracks.

Network Rail’s hard-pressed maintenance team employed the services of the regional contractor Dyer and Butler to clear the track and remove the debris from site. The line was closed for twelve hours after which it reopened with a 20 mph speed restriction that, at the time of writing, is still in place.

Other lines in the area were similarly affected. Twenty six washouts were recorded on the Looe Branch in Cornwall, all of which have now been repaired. The situation was similar on the Barnstable Branch which experienced twenty two washouts between Eggersford and Barnstable. Some were quite significant and the line was not reopened until early January 2013.

Overview

On Boxing Day, Steve managed to acquire the services of one of Network Rail’s two helicopters to survey the main routes, check the condition of the fence lines and gain an overview of the lie of the land. Where water was evident, he could estimate the likelihood of it affecting the railway in the future. Throughout this challenging period, Network Rail worked closely with the TOCs and FOCs. The Met Office continually provided forecasts and weather warnings which Steve and his team followed diligently. Everyone worked together and different teams combined and performed effectively. There where no accidents and everyone arrived home safe every day.

Some engineering lateral thinking proved invaluable and Steve ensured that ideas from the team were listened to, valued and evaluated.

At the end of the day, the dam at Cowley Bridge worked which was a satisfying outcome for a team of dedicated railway engineers who had experienced an interesting Christmas, although not one they would like to repeat.

Here’s to a dry 2013!

  • Bob Watt, ex-Glasgow Control

    As an Operations Controller (retired) who had plenty opportunity to be thankful for the work of the Engineering functions throughout difficult – unrelenting – spells, it is good to read of such ongoing dedication – well done to all!

  • Pc

    Thank you for your kind comments Bob, Hope you are enjoying your retirement but still enjoying rail engineer magaazine

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