By Elspeth Baecke, Structures Engineer, Railtrack Southern Zone.
Talk held on 7th March 1997
We are pleased to be able to publish here the text of Ms Baecke’s talk delivered on 7th March 1997 in the London Underground Ltd. Head Office at 55 Broadway. The talk had been liberally illustrated with overhead diagrams and slides, but I think you will still find the text interesting.
Until the age of 18 I had little contact with engineers and probably had even less understanding of their work. Bridges were of no interest to me and I hardly noticed that I was passing over or under them. But then I joined the Railway and everything changed.
The next few years found me becoming more and more hooked on bridges and now after 20 years I have around 8000 of them to look after.
I started life on the Railway as a tracer in the bridge drawing office, a post I obtained more because my father, also a railwayman, used to have lunch with the boss, than due to my drafting abilities. In those days girls weren’t taught technical drawing! After a while I started to take notice of the things that I was tracing -
And so in April 1994 I came to Railtrack. I am not going to speak too much about Railtrack and privatisation mainly because I find myself out of my depth -
Structures Engineers’ Role:
So what exactly does a Structures Engineer at Railtrack do?
Before I joined Railtrack I wasn’t quite so far up the managerial ladder so I used to be were involved with preparing schemes and contracts for repair works and then getting out on site on weekend possessions to give technical advice and watch that everything was done correctly. Now I seem to be forever in meetings or on the phone in the office: But that aside, my role really is a caretaker type role and I need to ensure that systems are in place to monitor the condition of the Zone’s structures and to have repairs and renewals done when necessary. This in reality means that I have a small army of bridge examiners working on contract to Railtrack who inspect all the structures on a set frequency and send condition reports to me. My assistant and I then wade through all this paper (we’ve had around 10,000 reports this year) and decide on any action required. This all has to be logged onto a database and the reports signed off and filed away. The theory is that we then get contracts each year to carry out the repairs but this in itself is a major task and so far we have relied heavily on our former colleagues at BR to organise it for us. Of course BRIS are Railtrack’s maintenance contractor for track, signalling, electricals and so on but structures are not included in the overall Infrastructure Maintenance Contract. So we have to place a separate contract for every job we need -
What has hit me most is the enormity of the task especially as South Zone is pretty unique. We have, as everyone knows, the Channel Tunnel traffic which has had a huge impact on the way we do things, but apart from that we have thousands of brick arches coming out of London, an extremely interesting but problematic area with extensive sea defences between Folkestone and Dover, 5 large Thames river bridges and a well-
Now all this may mean very little to you so I’m going to go on now to talk about a few particular problems and projects.
Starting with something nothing to do with bridges:
So I’m going to start with something which actually has nothing to do with bridges!
Because, although I mostly get involved with bridges, I also look after tunnels, sea defences, retaining walls, signal gantries and anything else that could be deemed a ‘Structure’.
So this is the stretch between Folkestone and Dover known as Folkestone Warren. At one end is Abbotscliffe Tunnels and the other is Martello. I’m sure many of you know much more about the history of this area, but I’m learning rapidly. The warren is a particular headache all the time and nature firmly rules the area. This is certainly nothing new and major slips have occurred here since 1877, the worst probably the one in 1915 when the whole line and cliffs moved some several yards towards the sea. In 1948 new drainage tunnels or headings were constructed to drain the high cliffs and since that time the area has been fairly stable apart from minor problems such as never ending holes which need filling up. The area is monitored frequently and we now intend to install a special system to alert the signal box directly if anything untoward happens.
At the other end of Abbotscliffe Tunnel which is over a mile long, the line passes the Channel Tunnel landfill site and onto Shakespeare Tunnel. The chalk in Shakespeare Cliff apparently was not so sound as Abbots Cliff and so the Engineer Sir William Cubitt took the precaution of driving two single line tunnels and constructing the arches in Gothic shape, so as to lessen the pressure on the crown. The distinctive shape of the bores makes this one of the most striking tunnel entrances anywhere on Britain’s Railways.
Past here the line was built on timber-
As I mentioned before, the running of trains for Channel Tunnel has had a huge impact on South Zone. Approximately 44 bridges over the railway had to be reconstructed to give increased clearances and several underbridges (bridges which carry the railway) were reconstructed to give increased capacity.
Two of these were the River Beult bridges at Headcorn reconstruction in 1994, at a cost of 3 million, which were old wheeltimber structures, life-
The local P.Way had to change rails between trains in those days (there was no such thing as possession) and they did not allow for an express train, which ran according to the channel tides. Charles Dickens never fully recovered from the experience and died on the fifth anniversary of the accident.
On to Bridges:
So now were onto bridges of which we have many types and sizes.
You nay recall this bridge in amongst the previous slides -
During the work another project started alongside when it became necessary to remove the redundant adjacent river bridge to enable the building of the Express Newspapers building at the South end. At that time there was a lot of speculation as to how the girders would be removed but I was nevertheless taken aback by one phone call I received. A foreign gentleman wanted to know what safety procedures would be needed if he wanted to lift the girders right over the top of my bridge and down onto barges in the river. Bearing in mind that my bridge is 25 metres wide I thought he was joking. I really thought he was a colleague winding me up but in the end that was exactly what the contractor did -
I’m sure some of you will have experienced the problems associated with bridge bashes. I have been involved with writing and actioning a strategy to help reduce the number of incidents on the Zone. We have earmarked the top 10 of 50 and will concentrate on those first.
When a bridge is hit Railtrack Control are usually the first to hear and the trains are stopped. A Field Manager, who is trained to be competent to assess if the structure has been badly damaged, then inspects the bridge. If it is not, ho can open the line at 5 mph but it cannot be reopened at line speed until a bridge examiner or engineer has inspected it and approved. If it is very bad I would be called out -
Another time my pager went off with the message that a bridge had fallen down from a bash so I decided I’d better go. The lorry looked pretty sad but the bridge was still intact fortunately-
Anyway, what we are pursuing with bridge bashing, is better advanced signing, infrared basins to warn drivers they are too high, better warning paint schemes.
Actually, I was sitting on the train last week drafting my notes for tonight and just as I was writing about bashing, the guard announced that we were being diverted due to a lorry hitting a bridge (Gun Lane I thought.’) -
These days I can’t get away from bridges and even on holiday in Scotland last year I ended up doing an impromptu inspection. The farmer at my Bed and Breakfast said he was worried about the little bridge down the road and, if he lent me his car, would I go and have a look. There was fortunately nothing wrong with it.
I guess I really feel quite privileged to have such an interesting job and I feel very strange about preserving our old structures whilst maintaining a safe railway for trains to run on.
Were only a year into the new organisation but the future for bridges looks good.