Probably my most challenging but most rewarding project ever was replacing the tracks within a 3.5km long railway tunnel with a ballast-less track system, GETRAC and RHEDA. The GETRAC system consisted of large sleepers, anchored onto an asphalt pavement. The ballast in the picture isn’t required for the structural integrity of the track; it is used for noise reduction and safety reasons for future maintenance work and evacuations, providing a flat surface to walk on.
The GETRAC system was a world’s first installation at the time, manufactured and delivered by Railone. This project was the Tunnel Brandleite in Germany, delivered for the German Railway by contractor STRABAG in 2004.
As the rail construction manager, I was responsible for all train logistics and the track installation. The railway line was closed for the duration of the works, which took place 24 hours a day 7 days per week.
We utilised conventional asphalt pavers and had to achieve a higher tolerance (+/- 4mm) than in traditional roadworks. This was achieved by using several thinner layers.
The vertical alignment was later fine-tuned with packers placed between the sleeper and the rail. To achieve the assembled track’s horizontal alignment and verify the vertical conformance, we utilised a conventional Plasser Theurer Unimat 08/3S tamping machine to adjust the track before fixing it into position, obviously without actual tamping.
The sleeper was fixed to the asphalt pavement with a grouted dowel. To grout 2 x 3.5km of track as fast as possible, we utilised small track vehicles from Robel, carrying a power generator, grout mixer, water tank and lights.
The advantages of the GETRAC system are the reasonably simple installation in comparison to concrete-based track systems such as RHEDA and the lower cost. The asphalt pavement base is particularly suitable to sit on natural rock surfaces, often found within old railway tunnels.
The project scope also included the replacement of a turnout, utilising the RHEDA system. Unlike the GETRAC system, the final alignment could not be achieved by utilising conventional track construction equipment. Manual survey and adjustment were required prior to fixing the system into position with concrete.
This project resulted in several innovations. For example, we designed and manufactured a sleeper laying excavator attachment specifically for the GETRAC sleepers which STRABAG patented upon completion of the project. Our installation method also became the blueprint for other contractors and future projects. The Tunnel Brandleite project defined industry best practice at the time.
Ballast-less track systems weren’t very common in Australia due to the lack of a fast rail network, but they are utilised within tunnels and on light rail projects.
Whilst a higher cost initially, the ballast-less track systems are a very good option over a 30-year maintenance window.
If you would like to find out more about this track system, visit the Railone website: https://www.railone.com/products-solutions/long-distance-and-freight-transport/ballastless-track-systems/getracr
I am still very passionate about rail infrastructure, in particular innovative solutions that require thinking beyond the square.
