At the heart of the tracks

5 March 2018 10:24

Under the motto of ‘Better and more’, NS and ProRail are working together intensively to raise the railway system and public transport in the Netherlands to a higher level. For example, on the Amsterdam - Utrecht line, trains are running every ten minutes. And by 2028, you should be able to catch intercity or sprinter trains every ten minutes on all the busy lines. This should put an end to the use of timetables.

Stability & innovation
To enable this, we are studying whether these busy lines or the railway tracks are up to handling this extra volume of trains. The line between Utrecht and 's Hertogenbosch is one of the lines where ProRail has commissioned BAM Infra Nederland to conduct a stability study to demonstrate this. This is a great job which was made possible by the creative collaboration between BAM Infraconsult, BAM Infra Rail and BAM Infra Energie & Water, and which has enabled us to develop an interesting innovation!

Since 1868
The railway line between Utrecht and 's Hertogenbosch, also referred to in Dutch as Lijn H or Staatslijn H, was opened on 1 November 1868. It crosses the three major rivers, the Lek, Waal and Maas, and for several years it was the only connecting link between these two parts of the Dutch railway network as they were otherwise separated by these rivers. Since this line is still largely in its original state, although some bridges have been replaced and parts of the tracks have been changed, relocated and doubled, a study to assess how this railway line would respond to increased train traffic definitely makes sense!

Soil testing
BAM Infraconsult collects the necessary field data as input for the Movares stability calculations. We collect soil samples by geotechnical drilling and then study the samples in the laboratory to establish the natural properties of the soil. We also probe the soil by driving our measuring equipment into the soil in order to establish its hardness and composition. And we conduct a height measurement to determine the cross-section of the railway track. Data from these studies is very important in order to determine the stability of the track and the soil under it.

Short periods in the night
Working on the tracks is complex and is accompanied by strict safety requirements. The short time available, the limited space and the safety regulations force us to constantly innovate and thus ensure that our efforts achieve a maximum effect.

Michel Bosboom (Soil Investigation project leader with BAM Infraconsult): ‘For the soil investigation of the Utrecht - 's Hertogenbosch railway track, this means that we carry this out in short train-free periods of no more than 4 hours at the longest, so as to minimize any disruption for passengers. An extra complication is that we have to probe the soil to great depths in between the rails, instead of in the available space between the tracks or in the track inspection path. The greater depths required around the track make this especially hard to do using existing traditional means.’

Road/rail crane
Michel: ‘We hired BAM Infra Rail to help us find a solution to this problem. The came up with a design for a successful probing frame based on existing rail equipment. They secured the probing unit to a road/rail crane combined with a ballast frame to provide extra weight.’

The Materieeldienst of BAM Infra Energie & Water in Nieuwleusen then further developed this basic design into a working solution. Together with BAM Infraconsult and the safety personnel of BAM Infra Nederland, they also carried out an RI&E risk assessment and a Task Risk Analysis. This has resulted in two safe, CE-marked equipment sets that comply with the European directives. This has been a great example of working together and bundling expertise!

At the heart of the tracks
The challenge of ‘how to probe to greater depths between the rails?’ was not the only problem we encountered. We remedied this together. For example, cutting through the thick, rock hard, solidified layer of ballast with our measuring equipment with our measuring equipment, and quickly restoring it to its original state after probing, is difficult. The solution: a flight auger. We use this to introduce a steel pipe into the ballast layer. After removing the ballast, we then apply the measuring equipment through the pipe. And once we've finished probing, we remove the measuring equipment, fill the steel pipe with ballast, and remove the pipe again. A piece of cake!

We are ready for it
The new track probing units will be operational in December. The results so far have fully met our expectations. We will finish the field investigation by early March and Movares can then start doing the stability calculations. We expect that we will be investigating 'at the heart of the tracks' much more often in the near future. We are ready for it!