Tanners Hill Flydown – Part 2

In Part 1 of this series we saw how and why the Tanners Hill Flydown came into existence. We also reported on the apparent need to double it in advance of enhanced Thameslink services, and the desire to do the work before major Thameslink construction at London Bridge commenced, during which fewer platforms would be in use at London Bridge.

In July 2011 Balfour Beatty was awarded the contract to carry out the work. Work at the site started in earnest during Easter 2012, which included replacing the existing track on the flydown and installing the necessary extra point on the up Nunhead line. This will enable a connection to the future up line on the flydown.

Christmas is a time for Engineering Work

With a major project like this there was a limit to how much work could be done in advance of the main work. Even so the advance work was reported as being enormously disruptive for the residents. The only realistic time to do the main work was between Christmas and the New Year, as this was the only time South Eastern services can cope with all commuter traffic through this area only being able to use two tracks. This resulted in a preferred completion date of May 2013, when Thameslink work would start to affect London Bridge.

There was an awful lot of project planning to be done. Applications to Lewisham council included an incredible level of detail of the works involved and what steps would be carried out to minimise noise. This included the hydraulic bursting of a bridge abutment to be demolished, rather than the traditional noisy “pecking” of the structure with a jackhammer. For this purpose holes had been drilled into the structure the previous Easter.

Clearly the residents had concerns. The website mentioned gives more details.

Lewisham Council were heavily involved as their approval was needed. In reality though, all they could do was oversee and ensure that Network Rail had done everything reasonable that they could do to minimise disruption and complied with all the statutory procedures. Inevitably the work would involve a lot of noise due to the amount of concrete breaking required and one can understand the frustration of the residents in being subjected to this over Christmas.

Advance Works

Although the real work started in earnest just before Christmas 2012 quite a lot of advanced work was carried out. The following photos show the work done which had to be done during the limited possessions available.

This picture shows the base for the new abutment behind the signal. Once in place the metal span can be supported and the remainder of the bridge demolished.

The steel support is now in place.

The sides of the bridge now need to be strengthened at the point where they are above the steel support.

It is now clear exactly where the second track will go

The Christmas Blockade

By Christmas Day a new temporary point had been installed leading to an extremely short temporary siding which improved rail access to the bridge span due to be demolished. The next few days saw the existing masonry span demolished and the abutments removed. The bulk of this work was in fact done with a jackhammer and was very noisy. Although the level of noise dropped dramatically as one went further from the site, it could be heard within quite a large residential area.

On Boxing Day everything was ready for demolition to start

By the 28th December the concrete abutments had still not been completely demolished and removed, and it looked like work was well behind schedule. Breaking concrete is an engineer’s nightmare when on a tight schedule as it can give unexpected problems. When installing the famous “umbrella” at Oxford Circus, for example, during construction of the Victoria line the most difficult and problematic part of this complex job turned out to be removing the cobblestones, which were set in very hard concrete and were completely resistant to pneumatic drills.

Finally the abutments are removed and there is room for a second track

It appears from a reader’s comment on Part 1 of this article that there was indeed a problem and as a result the mobile crane that was on site for many days (no doubt at great expense) was of very limited, if any, use. The setback would have almost certainly have been due to the unexpected hardness of the concrete and must have had a considerable impact on length of time residents were subject to extreme noise levels, which would have undoubtedly have been higher than predicted.

It is believed that this temporary footbridge always was part of the plan, but it was also part of the plan that below it would be the extended bridge but awaiting utilities and resurfacing work.

The extension to the bridge. We will have to wait and see when this will be installed.

There are lots more (over 200) pictures available in Unravelled’s St Johns set in the LR Photo Pool, for those who are interested in seeing more. There are also a few “propaganda pictures” taken by the residents including this mildly amusing one.

The future

One would hope the setback with this aspect of the Thameslink Programme can be recovered from quite quickly so that it does not impact on later work. It is a very small part of the Thameslink Programme and it is not immediately clear from the works documents whether it is a critical part or not. We will look into this and any consequential revised timescales. In the future we look forward to reporting on the bigger works involving the Bermondsey Diveunder and of course the massive changes at London Bridge. On top of that we will of course do articles on the historical background so that one can understand why we are where we are.

Written by Pedantic of Purley