Works until July 2011

During  recent weeks the reconstruction works on the Denklingen bridge have proceeded well - thanks to the hard work of many volunteers, who have already invested more than 500 hours of work. Also, thanks to the restless planning team and last but not least thanks to the more than 100 donors who have already contributed €12,694. Our sincere thank goes to each of them!

The positive feedback of the monument protection agents of the District Council of Cologne re-assured and motivated us in our activities. During on-site inspections they had the opportunity to get a picture of the works and to give specialist advice..

Currently the bridge offers a surprising sight: The concrete span has been excavated and from  above it looks as though one was standing on the vault of a church’s ceiling. One half of the work is nearly done. Now we can start sealing the concrete and thereby protecting it. Then we have to re-instate everything in the reverse order. But one step after the other:

The most significant original decision was to split the reconstruction of the bridge into two halves:
In 2010/2011 the concrete part will be reconstructed and in 2011/2012 the temporary steel bridge that had been fitted after WW II will also be reconstructed.

But how to access the concrete that has to be sealed? After an intense planning phase the works began on 23rd.November 2010 with the cutting, lifting and storing of 30m (roughly 33yd.) of track. This was done by the company "Hering Gleis- und Ingenieurbau". We recommend you to have a look at the photo gallery - this is not an everyday sight. After this step there was no track anymore - just a thick layer of ballast was before us.

Within four days the same company excavated approximately 180 cubic metres (233 cubic yards) of stone from the bridge and transported it to Waldbröl. What the bucket excavator couldn't get hold of in the depth of the span ends had to be removed manually - half a lorry load, in the end. Then there was no gravel anymore inside the bridge, but a layer of bricks - 3,000 altogether. These bricks in conjunction with a thin layer of fine sand served the purpose of protecting  the sealing below. But as we had to expose the concrete all the bricks had to be removed manually and be piled up tidily so as to be able to recycle as many of them as possible. Broken bricks will be replaced with reclaimed old bricks from demolished houses. Now there were no longer any bricks before us, but just a layer of decayed sealing material and in many places the bare concrete.

And now the core problem became obvious: Below the bricks we found big water cavities. The drainage pipes had obviously got choked decades ago and so the water stood inside the bridge. Therefore we had to establish new drainage openings by drilling core holes. The experts predicted a thickness of the walls of 70 cm (2 ft. 3 ins.), but the drill did not break-through until 1.4 m (4 ft. 7 ins.) - and the water shot out immediately.

In the course of many expert meetings the decision was made about the most suitable sealing method. For the application of the sealing material we faced the problem that none of the present sealing materials could be used in conjunction with the old tar layer. In order not to risk the new sealing layer being eaten away by the old tar every tiny bit of tar had to be removed in painstaking detail works. Also for this stage our colleagues developed a fair amount of creativity to solve the problems.

The new sealing material has to meet a lot of requirements: The concrete must be protected against moisture for many decades. The sealing itself has to resist the weight of the infill above or even be protected against the infill. And because of the restricted accessibility of the area the material had to be easy to handle. It turned out that the best method required a smooth base. So after the tar has been removed a cement render is going to be applied. Subsequently the area will be sealed and the infill will be returned. Photos of these works can be found in our bridge photo gallery.

At the same time another area of work arose: The stone slabs of the trackside walkway on top of the bridge turned out to be in a worse shape than expected and urgently need to be improved. So here as well: Analysing the situation, consulting the experts, examining possible in-house efforts, making decisions - and starting. Now the stone slabs are being turned over onto temporary framework, the underside is dressed and then they are turned  back to their original position and fixed.

Future prospects

The first work site is followed by the second one. By our own work input, as well as by strict expense control we did not exceed the budget. The outsourcing of the works on the steel bridge imposes significantly more bureaucracy, but promises financial savings. However: Without further donations we cannot reconstruct the steel part. Therefore we would be very glad if you would continue to give financial support for this project and also advertise it among your colleagues and friends. Only the reconstruction can make the bridge and also the upper Wiehltalbahn fully traffic-bearing again and fit for the future.