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Bonkers Blog March 2019

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17 March - Network Rail explain the Barnehurst landslip and TfL fails to say anything about their DLR map which includes Abbey Wood

The last hour of the Transport Users’ Sub-Committee meeting may not have been especially interesting but the first 45 minutes revealed quite a lot about last month’s land slip at Barnehurst which stopped all trains for a week. Both Network Rail and Southeastern were represented.

It was the fourth Barnehurst land slip in the past ten years and Network Rail had sent their Route Asset Manager for Geotechnical Drainage and Off Track Assets (Derek Butcher) to the meeting. He explained that he looked after “embankments and cuttings, drainage, trees and access points”.

I know that Chairman Val Clark tries to turn her ignorance of transport matters into a virtue but I thought that the need to explain the difference between a railway embankment and a cutting was somewhat extreme.
Committee The line through Barnehurst opened in 1895 and the Victorians built it on the cheap. They bought up as little land as possible and so the cuttings are much steeper sided than they should be; they slipped during construction and they have been inclined to do so when it rains ever since. The Barnehurst cutting is east of the station and one and a half miles long.

Because it is one of Network Rail’s worst land slip problems electronic monitors were installed following the previous land slip and February’s one made history by being the first to alert staff over the mobile phone network so that trains could be brought to a halt before hitting any obstruction. The alarms went off at about three thirty on the morning of Monday 11th February. The five o’clock train went through very slowly and the driver reported a tree down and a signalling cabinet had been pushed on to the track. The line was closed shortly afterwards, both tracks because of the need to bring in heavy engineering equipment.

Since February the number of sensors east of Barnehurst has been increased fourfold.

The problem arises because there is a layer of blue grey clay near the bottom of the cutting and water runs down to that level and a line of springs form at the clay level which softens and moves.

Successive slippages have been adjacent to each other and the theory is that retaining walls act as dams and displace the water to the next available spot. It is currently being investigated and a formal report will become available within the next couple of weeks.

Another 400 metres of cutting nearer to Barnehurst station has been identified as vulnerable and will be given attention within the next five years. The whole one and a half mile section cannot be dealt with any time soon for budgetary reasons. “It would cost £20 million. One sixth of the available budget on 1% of [cutting] assets.”

The Chairman said she “couldn’t understand why Network Rail did not want to do the whole bit in advance”. She isn’t very bright is she? However the Network Rail man was patient and explained the budget again and that the 50 metres that slipped in February caused a week of line closure, one and a half miles “would take a significant amount of time”.

Councillor Clark said residents blamed tree removal and Mr. Butcher said that trees represented a very difficult balancing act between safety, leaf fall, ground stabilisation and trees coming down during storms. Generally trees within seven metres of the track are cleared.

Councillor Stefano Borella (Labour, Slade Green & Northend) asked why the Bexleyheath line to London is the only one without the ability to turn around trains somewhere along the route. The Woolwich line has Plumstead and Slade Green and the Crayford loop has Sidcup, but there is nothing for the line from Barnehurst. I don’t think he expected to get a wholly satisfactory answer so presumably he is not too disappointed with the one he was given. However a promise was made to submit the question to a higher authority.

Stefano being something of a railway geek knew that problems with cuttings have sometimes been solved by construction of a tunnel. Unfortunately estimates are that it would cost more than fixing the cutting and might take the line out of use for even longer.

Councillor June Slaughter’s (Conservative, Sidcup) question elicited confirmation that the removal of trees and landslips are statistically linked in the obvious way, sometimes the connection is a quick one.

Councillor Melvin Seymour (Conservative, Crayford) was critical of the fact that there had been four landslips in ten years and only now had a specialist team of experts been commissioned to report on the problem. Mr. Butcher accepted that Network Rail could have been more proactive than they had been but their repaired sections, on which about £7 million had been spent on the engineering alone, had never failed. He accepted that the consequential disruption would have been costly too.

Those costs included passenger compensation and replacement bus services. Buses had provided a 30 minute interval service to Lewisham and were very little used, an average of fewer than 15 people on each one. Councillor Borella suggested it might have made more sense to run an express bus service to Abbey Wood. The Southeastern man welcomed the suggestion.

Councillor Clark thought that buses should have been run all the way into London. Clueless isn’t she?

Delay Repay compensation rates had been doubled for affected passengers.

The ongoing signalling problems in Lewisham are regarded as “top priority” and will have £85 million thrown at them over the Easter holiday weekend as all railway users (Woolwich and Bexleyheath lines) will find to their cost. There will be no trains for three days. Another £81 million will be spent in and around Hither Green next year. The total bill will be £300 million and, according to Councillor Clark, the disruption will continue for a year.

It was at this point that Cabinet Member Craske posed his faltering and rambling three minute err and umm ridden question. I was tempted to place an audio clip here to see if you will think what I have been thinking, but somehow or other Mr. Butcher was able to formulate a response revolving around his contingency plans.

Following the criticism of the station skipping leaf fall timetable introduced last Autumn, Southeastern announced that they would not skip adjacent stations in future.

The Agenda included proposals for an extension of the Docklands Light Railway but with no one from TfL bothering to put in an appearance there was no discussion on it. The map below indicates possible routes (the blue lines) to both Abbey Wood and Belvedere.

There are two options around the Beckton Depot connecting to Thamesmead Central, one of them via Thamesmead West. The route then runs down to Eastern Way with one possible alignment along Harrow Manorway to Abbey Wood with the alternative skirting Southmere Lake and thence to Abbey Wood via Yarnton Way and another along Yarnton Way into Belvedere.

No clue as to dates but if you have already left school you should probably not get your hopes up.
DLR
The map appears to show an Overground line from Barking too (Orange line) but it was not mentioned in either the Agenda or the meeting itself.

 

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