Full points upgrade

Compacting ballast on the railway with the HD 10C VV

Hamm compact rollers in railway construction

Ballast pre-compaction with the HD 10C VV tandem roller

HD CompactLine compact rollers are all-rounders, suitable for asphalt construction, earthworks and gardening and landscaping. What many people don't realize is: They can also be used to construct railways. That's why the internationally operational rail engineering group Rhomberg Sersa Rail Group, a full service provider for rail infrastructure, is making full use of the benefits of the HD 10C VV tandem roller from Hamm to, among other things, upgrade the points. Compacting the ballast is an integral part of the pre-compaction process. If a ballast bed is not cleanly compacted and homogenized, this can lead to costly processes further down the line.

Aarau | Switzerland

Compact tandem rollers can achieve optimum compacting results on ballast layers, frost protection layers and base courses, as well as water-bound road surfaces and asphalt layers. And, as demonstrated here by the Rhomberg Sersa Rail Group, they even find application in railway construction.

Ideally suited for railway construction

With over 200 models between 1.4 and 25 t, Hamm offers an extremely diverse range of rollers for virtually every application. The articulated compact rollers of the HD CompactLine are ideally suited to railway construction. This is partly down to their relatively low weight.

"The weight of a roller is a major consideration in railway construction," explains Jürgen Franzen, foreman for the Rhomberg Sersa Rail Group. "Even from around three metric tons upward, you can see clear differences in the tracks the roller leaves behind. However, the actual problem is hard to see with the naked eye – namely, the graining. This means there are certain fracture points in the ballast. However, the ballast stones need to have certain properties to stick together as required. Too much weight would impair this characteristic. Plus, the compact proportions of the HD 10C VV also make it particularly easy to load onto transport vehicles, so it's a great option for transporting around."

Every box has to be ticked:

Foreman Jürgen Franzen speaks to René Neujahr, sitting atop the Hamm HD 10C VV during the upgrade of the points in the standard gauge – the task of replacing the points also involves replacing ballast, renovating the substrate, and cleaning the ballast.

The condition of the ballast bed is critical:

The condition of the ballast bed upon which the rails are laid is one of the determining factors for the quality of the guideway. The ballast has a whole host of important jobs to fulfil, which require it to have very specific properties. The basic prerequisites: The ballast follows a clearly defined distribution of stone sizes and fulfils various geometric, physical and chemical requirements.

Foreman Jürgen Franzen speaks to René Neujahr, sitting atop the Hamm HD 10C VV

Full points upgrade in Aarau

The works to upgrade the points generally take place during normal operation of trains on the adjacent track. In Aarau, the reconstruction work will be carried out on a three-shift rotation, with a total of five shifts expected. The experienced foreman Jürgen Franzen from reconstruction team 2 explains: "What you see here is the W+, which cleans the ballast. Ballast cleaning involves lifting up the existing ballast material, mechanically cleaning it and then replacing it. Then we can reinstall the points with a crane."

While the W+ does its thing, the Hamm HD 10C VV is hard at work compacting the freshly deposited ballast. Each work step intertwines perfectly with the next and they build on each other. This is important because the rail traffic generally resumes operations immediately after the points are installed, since closures are calculated to an absolute minimum.

Once the ballast has been lifted up by the W+ system, cleaned and put back down, the points are upgraded.

Even while the W+ is doing its thing, the HD 10C VV is compacting the ballast. The tandem roller with two vibrating roller drums provides not only the initial compaction, but also a flat surface on which to subsequently lay the sleepers flat.

The deposited material provides, in principle, a degree of compactness. The ballast here already has a certain sticking quality. The roller compensates for this with compression and vibration. This way, the material fuses together better.

Once the ballast has been subject to initial compaction by the HD 10C VV, the mechanical surfacing stage of the points construction begins. Then, it is mechanically tamped to further the homogenize the ballast.

All in a day's work – upgrading points using the W+ and Hamm roller

Even while the W+ is doing its thing, the HD 10C VV is compacting the ballast.

The roller compensates for the ballast's sticking quality by means of compression and vibration.

Initial compaction of the ballast using the HD 10C VV

Rollers in railway construction – what the experts have to say

"Here on the railway, you can't simply set off with your roller without giving it any thought," explains René Neujahr. "If you did that, the concrete sleepers might crack later on. The HD 10C VV has everything I could possibly need to do my job properly. It's intuitive to operate. It has really impressive visibility and excellent driving and handling characteristics."

The HD 10C VV has everything I could possibly need to do my job properly. It's intuitive to operate. It has really impressive visibility and excellent driving and handling characteristics."

René Neujahr, operator for Rhomberg Sersa Rail Group

And Jürgen Franzen adds: "If there's a raised section in the centre beneath a sleeper, caused by an oversight in the compacting stage, that sleeper could crack. That is relatively easily remedied if it is a track sleeper. But the way the points are here in Aarau means we can't implicate any other points. So everything would grind to a halt. You can tamp it, but you would still need to remove the sleeper afterwards and properly refurbish it. Our Hamm roller helps ensure this doesn't happen."

"If there's a raised section in the centre beneath a sleeper, caused by an oversight in the compacting stage, that sleeper could crack. So everything would grind to a halt. Our Hamm roller helps ensure this doesn't happen."

Jürgen Franzen, foreman for Rhomberg Sersa Rail Group

Press/media kit

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