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Island floods

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Just off the south coast of England is one of the more unusual parts of the UK rail network. The Island Line is an electrified route running down the east side of the Isle of Wight. It runs up a pier, to the terminus at Ryde Pier Head station where it connects with ferries to the mainland. The other terminus, 8.1/2 [use half fraction] miles away, is at Shanklin.

As well as the pier, there are other novelties. The line is electrified with a third rail at 630V DC. The track in the tunnel under Ryde was raised in 1966 to help prevent flooding, and as a result the headroom is now so low that standard trains cannot run through it. The solution was to use redundant London Underground tube stock. The current Class 483 trains were originally 1938 tube stock making them, at 75 years old, the oldest trains currently in network passenger service anywhere in the UK.

Assessing the damage

As part of its franchise agreement, South West Trains runs the Island Line and also maintains it. The workforce includes a small infrastructure team and also, interestingly, the signallers who operate the Island Line signal box located at Ryde St Johns Road. However, when major track remedial work is needed, assistance has to be brought in.

So when flooding in the Ryde area over Christmas caused damage to the line, a meeting was arranged between South West Trains’ head of fleet production and contractor Keltbray Rail and a line inspection was carried out on the 27 December to assess the damage.

This revealed that there were 20 sites over a three mile section where the track ballast (shingle) had either been completely washed away or moved by the flooding. Some of the sites between Ryde Esplanade and Ryde St Johns Road were not too severe and it was a case of just moving the shingle and placing additional ballast. However, from Ryde St Johns Road to Smallbrook and beyond there was extensive damage. This included washouts where the track ballast was completely washedBallast is replaced under tracks near to Smallbrook Junction [online] away, sleepers were also missing.

At Smallbrook station there was a 20-metre section where there was simply no ballast at all – it had all been scoured down to a depth of about one metre.

Planning started on Monday 30 December. Due to the location, this included getting in plant, staff and supplies – made doubly difficult as it was still the Christmas and New Year holidays. However, arrangements were put in place and some 600 tonnes of ballast was delivered by ferry over the weekend, allowing engineers to begin repair work on Monday.

Working from both ends

Work started on Monday 6 January with two separate gangs – one working from Ryde Esplanade towards Smallbrook, and the other working from Sandown towards Smallbrook.

Ryde tunnel itself had been flooded so, while Keltbray cleared debris and undertook brickwork repairs to the Up line portal, specialist engineers from S&T Cover undertook a complete renewal of the signalling lineside cables through the tunnel, including the installation of two new location cases. As well as the cables, twenty track circuit impedance bonds were upgraded and nine track circuits were set up and tested.

All of the replacement equipment had to be brought onto the island as well as the staff to complete the signalling work. Once on the island, full integration and liaison was undertaken with Keltbray and Island Line Trains to complete the work within the demanding timescales, despite the continuing bad weather.

Meanwhile, new ballast was hauled to the washout sites where shingle was cleared and topped up with fresh ballast. This was compacted, a few sleepers were replaced, and then the track tamped using an RRV attachment.

The track at Smallbrook station required substantial work and repairs were also needed to the platform. 90 Grundomat piles were inserted to stabilise the ground. These are a form of mini-pile in which steel tubular piles are welded together, installed, and then infilled with concrete and reinforcement bar. This work was undertaken to improve the stability of the bank that borders the track at this location.

New flood relief drains were installed, and ballast boards fitted to help keep them clear. New fencing was erected on both sides of the track which was realigned after the ballast had been laid and compacted.

The opportunity was taken, as this work was being carried out, to strengthen the infrastructure so that it could more easily withstand any future bad weather.

All the while, the teams were aiming to complete by 20 January. This date had been set bearing in mind the number of affected sites and the logistical difficulties of having to bring everything onto the island. As it happened, everything went well. Both Keltbray and S&T Cover finished their work early, and the line reopened early on 18 January for testing with the normal train service resuming on Sunday 19 January.

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