Network Rail was this week facing further work to fix damaged signalling, track and electrified rail following a mudslide in south London last week, despite already carrying out a major clean-up operation.
The rail operator and owner said there would be “ongoing consequences” from the mudslide that hit tracks between East Croydon and South Croydon stations, one of which was the potential need to replace all five tracks affected.
The slip was triggered when a 305mm diameter Thames Water cast iron water main, 150m away from the tracks and buried 4.5m below ground, burst and flooded the ground, destabilising the slope.
Train services were halted within two hours of water being seen by a train driver on the morning of Monday 1 August, causing massive disruption to rail services out of London and to Gatwick airport (see timeline, right).
Network Rail ordered operators First Capital Connect, Southern and Gatwick Express to initially stop running trains on the three slow tracks that were most affected alongside the cutting, and all services were stopped by 11.30am as the mud reached the furthermost tracks.
Work around the clock
Around 70 maintenance workers and 10 civil engineers worked around the clock to reinstate the line. Excavators removed around 2,500t of mud and sand from the tracks to open two of the five lines by that evening.
Further work continued to bring two more lines back into operation by Wednesday 3 August while one line remained closed as NCE went to press.
“There has been damage to the signalling and the electrification and the quality of the track has been affected but that’s for maintenance to manage”
Network Rail programme manager Simon Brazier
Site workers also had to carry out re-profiling of the slope to stabilise the damage, reducing the Thanet sand slope from a 60° angle from the horizontal to 45°.
Network Rail is now assessing the full repair and its costs. Programme manager Simon Brazier said he was unsure how much the clear-up would cost although a spokesman said the infrastructure bill would run to “several million pounds”.
“It’s very likely we will have to re-lay the tracks,” Brazier said. “Silt has blocked the track drain and contaminated the ballast.
“There are ongoing consequences as we will need future occupation of the five tracks. There has been damage to the signalling and the electrification and the quality of the track has been affected but that’s for maintenance to manage.”
Brazier said it was fortunate that no trains were hit by the slip.
However, around 80,000 commuters were caught up in the chaos and connections were cut to Gatwick airport causing travellers to miss flights.
Thames Water engineers battled to replace the burst section of pipe on the evening of Tuesday 2 August, after working through Monday night.
Workers cut out a section of the burst pipe and replaced it with a new section of ductile steel pipe.
Thames Water estimated that 700,000l of water escaped from the pipe before the supply to the main was shut off on Monday afternoon.
An investigation is now ongoing into the potential causes of the burst incident. Thames Water said this investigation will also examine whether the rest of the main could be at risk of a similar burst − but a spokesman said there is currently “no indication of an increased risk”.
Network Rail ‘to seek compensation’
Thames Water added that the 15,000 customers served by the main had not suffered any service disruptions.
The company said it predicts potential flooding and impacts from any mains bursting close to other key assets, and that a leakage assessment is undertaken for this main on a yearly basis.
“This helps us to monitor the pipes and improvement programmes to best manage the risk within the network,” said a spokesman. Maintenance work on mains is prioritised by the results of these leakage assessments, and the main’s burst history.
The firm said that no problems had been reported on this section of main over the past two years.
Network Rail this week confirmed that it will seek compensation for the “seven figure sum” of costs that it incurred as a result of the landslip.
A spokesman said: “The damages caused here were not our fault, but due to the delays in services we have had to compensate the train companies.
“We are therefore seeking compensation from Thames Water for a failure of its infrastructure.”
A spokesman for the Association of Train Operating Companies said operators would have been compensated for delays by Network Rail as part of their Track Access Agreements.
“Schedule 8 of the agreement says that every four weeks operators receive money for delays, thus they will automatically receive compensation,” the spokesman said.
Network Rail had previously sought compensation from Thames Water in 2003, after a similar incident in which a water main burst and damaged track at Canonbury station in north London.
Industry body Water UK legal advisor David Strang said the finer details of this week’s case were unclear, but noted that a water company whose burst pipe causes loss or damage is likely to be financially liable under Section 209 of the Water Industry Act 1991.
“You would be liable to pay compensation on whatever it costs to remedy the problem,” Strang said. “There are a number of exceptions but they are quite limited.” It is unclear whether any of the exceptions apply to Thames Water in this case.
It is up to individual water companies to decide how to manage pipes that lie close to other infrastructure, Strang said.
A spokesman for water regulator Ofwat said water companies are asked to identify areas of high risk in their network in their five-yearly risk management plans, but the regulator would not penalise companies for indivdual bursts.
The Water Industry Act 1991 is “a big incentive for them to manage the risk appropriately,” he said.