Keeping the line dry and running fast

Next month will see the reopening of the rail link between Warsaw and Radom, work that began in September 2015. Nearly six years to modernise a 100km-long line that took just 20 months to build in the mid 1930s. There will be a separate post soon to celebrate the reopening, but today I'd like to focus on just one aspect of this investment - the drainage.

The modernised line offers significant improvements in journey time. Looking at an old timetable from before the work started, the fastest time between W-wa Śródmieście and Chynów was 1 hour and 1 minute; from next month it will be down to 41 minutes to cover the 43km. This means trains will be averaging 60 km/h including station stops, hitting maximum speeds of 100km/h. There is potential to improve that much further in future. However, this can only happen if the tracks remain as smooth as when they were laid; the biggest threat to that is erosion by rainwater.

Climate change brings with it a new meteorological certainty: uncertainty. Severe weather events - in particular droughts or floods - will become more common and less predictable. The railway engineers and designers who planned the modernisation did so taking into account the likelihood of flash floods and droughts. Intense downpours can suddenly dump vast torrents of water into trackside ditches, which, if not properly managed, will over time carve away the underpinnings of embankments and wash away cuttings. If these come interspersed with dry periods, hard-baked topsoil that doesn't soak up rainwater leaves the land more vulnerable to sudden surges of water. 

Erosion will result in the track becoming bumpy and uneven, leading, as has been the case, to ever greater speed restrictions. In the years before the modernisation, it took longer to get from Warsaw to Radom than it did before the war by steam train, with speed restricted on much of the line to 60km/h (38mph).

Any upgrade to the Radom line had to be done in tandem with drainage work. And this had to be done in the context of the lands on either side of the line. Beyond W-wa Okęcie and excepting Piaseczno, it's mainly rural land or forest all the way until the line reaches the northern outskirts of Radom. Here in Chynów, its mainly orchards. The railway could not keep itself dry by merely diverting floodwaters into neighbouring agricultural lands. Joined-up planning was needed; the results are expensive. Culverts and ditches cross orchards that empty into trackside ditches, water pumped along to prevent lakes from forming locally; retention ponds built where necessary. None of this flood-prevention infrastructure was present on this line before its modernisation. [Worth taking a look at the Corpus Christi flood of 2010 to see how much damage heavy rain can cause if there's no proper drainage in place.]

Around one-third of all the work on the line has been to do with keeping rainwater from eroding the foundations of the embankments and from washing away the cuttings. New culverts have been dug under the line, pumping stations built at suitable intervals, and drainage ditches cut alongside the line, some buried in pipes, others covered with concrete slabs. Getting the balance right between leaving grassy earth (needs plentiful and expensive maintenance!) and huge concrete gullies (expensive, bad for the local ecosystem!) is difficult.

Below: looking along the line towards Chynów station (just over the brow of the hill). Note the pumping station on the horizon, and the underground channel running alongside the track at the foot of the embankment. It exits by the concrete culvert which allows water on either side of the embankment to find its level.

Below: on the other side of the road running parallel to the tracks, another drainage ditch for collecting water from the orchards and feeding into the same culvert. Note the pumping station, top right. These orchards have been very prone to flooding; after heavy rain the sound of diesel pumping engines syphoning water away could be heard from my działka at the top of the road (to the left). Now, hopefully, the orchards have become self-draining.

Similar pictures can be taken up and down the line all the way from Warsaw to Radom. The work is not over yet. In Jeziorki the east side of the track is now having its drainage ditch fitted with 'U'-shaped concrete inserts to prevent erosion, topped off with concrete slabs to prevent debris blocking the flow of water (below).

It was 91 years between the line's construction and its first major modernisation (excepting of course the post-war reconstruction). I hope that the current works just approaching their end will be good for at least half that time, and that trains will be able to run along the new tracks ever faster, cutting journey time and encouraging more people to abandon their cars in favour of trains.

This time five years ago:
Politics - the importance of fact.

This time six years ago:
Rural Mazovian toponyms

This time seven years ago:
Carrying the weight on both shoulders

This time eight years ago:
Railway history - the big picture

This time ten years ago:
A new lick of paint form W-wa Powiśle

This time 11 years ago:
The ingredients of success