Replacing a railway culvert in a polder
16 July 2020
As Work Planner, Bas van Dam (26) is closely involved in the Waddinxveen Railway Culvert Renovation project. It is his first large project since he started working at Strukton Infratechnieken eighteen months ago. Not your average everyday job. Quite the contrary.
Near Waddinxveen, between the Gouda and Zoetermeer-Oost railway stations, the tracks cross a small waterway. The railway bridge – ProRail refers to it as a railway culvert – dates from the 1800’s and is therefore due for replacement. Strukton Infratechnieken, where I have been working since I completed my Industrial Engineering and Management studies eighteen months ago, was awarded a contract to install a new railway culvert. The actual implementation work will require two downtimes: twice one weekend.
It may sound like a simple job, but it’s anything but that
What is difficult about this job is that adjacent to the culvert there is an underpass for cars. This means that we must do everything we can to ensure the underpass does not shift when we remove the railway culvert. ProRail suggested we install a sheet pile wall, but that will take too much time. We therefore suggested a different, unique method: to constantly prop the culvert. We will be using struts to push the walls on both sides away from each other, including during demolition, so that the entire structure continues to be under tension. This way we prevent the full weight of the underpass to sag towards the railway culvert.
During the first downtime period we drilled foundation piles at the four corners of the railway culvert. The piles are also located between the two tracks. A subsidence-proof plate will be mounted on top of them. This is a kind of concrete floor that connects the underpass and the railway culvert together as it were. During the second train-free weekend we will do the rest of the work: Strukton Rail will remove the tracks and the ballast for us; we will demolish the existing culvert, place longitudinal girders on the already constructed footings and position the culvert elements between the longitudinal girders. In addition, under contract with ProRail and in cooperation with Gasunie we will be replacing an old gas pipeline passing below the tracks.
If everything goes well, after the second train-free weekend most of the work will be complete and all that is then left will be some finishing work, such as reinstalling the fencing around the railway tracks and demobilising the construction site.
“On paper everything looks right, but of course in actual practice things are always somewhat tense”
Everything looks right on paper
It may sound like a simple job, but it’s anything but that. First, there is the time pressure, as usual for any railway work. There is a great deal of work to do in a short period of time. The second train-free weekend starts on Friday evening at 01:00 a.m. and the railway has to be back in operation on Monday at 05:00 a.m.
And another issue: the lifting crane. The culvert elements are too heavy – they weigh up to 60 tonnes – to lift with an ordinary mobile crane. This is why we will be using a 750-tonne crane. We will create a temporary dam in the water on which the crane will be placed. Naturally, all of this has been calculated in advance and on paper everything looks right, but of course in actual practice things are always somewhat tense.
Handling the peripheral activities
I am the Work Planner for this project. This means that for me the focus is on the preparatory activities. Together with the Construction Supervisor I develop the work plans, look after part of the procurement and apply for permits. The latter is quite the job, because we are dealing with many parties, including ProRail, the municipality, Gasunie and the water company. In terms of any inconvenience to the local community, things are relatively straightforward: there is only one house near the railway and somewhat further up there are a few companies, but other than that there’s only the polder.
Fortunately, I not only sit in my office, but try to get outside as much as possible. Together with the Project Manager I deal with all peripheral activities during the downtime so that the construction crew can focus on doing the work. This means communicating with ProRail’s environment service and inspectors, performing inspections for subsequent reporting, consulting with ProRail about progress, that sort of thing.
I’ll be happy when everything goes well on the second weekend of implementation and the trains will be able to drive again on Monday morning. Better still, this will take a major burden off my shoulders. This is my first major project since I completed my studies and was hired by Strukton Infratechnieken. So it’s exciting, but also difficult. Especially the really in-depth technical discussions are sometimes difficult for me to follow. And here I am not even talking about the many railway abbreviations and jargon. There is enough of that to fill an entire dictionary. Fortunately, my colleagues are always prepared to explain things to me. While this may be a cliché, it is really true: I have learned more in my eighteen months with Strukton than I have learned during my four years of study.
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Several colleagues share their daily practice