No Ordinary Asphalt Job
Two HD 12e tandem rollers impress on an incline
Works to expand the Rabenleite Upper Reservoir in Bavaria saw the deployment of two electrically driven tandem rollers from Hamm AG.
An extraordinary construction site placed unique demands on man and machine: During the project, the edge of the upper reservoir basin was extended to significantly increase the Rabenleite’s storage capacity. The construction work succeeded in increasing the volume of the basin from the existing 1.5 million cubic meters by around 6% to roughly 1.59 million cubic meters. The perimeter of the ring dam was at 1,600 m and was raised by 77 cm.
The upper reservoir, alongside two other reservoirs and three hydropower plants, forms part of the Pfreimd power plant group. As long ago as the 1950s and 1960s, reservoirs were first being built to generate and store energy and in turn stabilize the power network. Since 2009, the power plant group has been managed by ENGIE Deutschland and has been expanding ever since.
Machines of the Wirtgen Group working in perfect harmony. Particularly impressive are the two Hamm rollers, compacting with precision and reliability on the incline.
Electrical Machines Excel on Slopes
The steep slopes of the upper reservoir basin, angled at around 40%, asked a lot of the deployed machines. Diesel machines have to be extensively modified to deal with such inclines. Conventional diesel machines have to undergo extensive modifications to deal with such conditions, whereas the electrically driven HD 12e machines from Hamm represent a straightforward and efficient alternative. These models are ready to work on inclines with only minimal adjustments. “The electric rollers from Hamm are not limited regarding their maximum incline, and changes in incline – such as those caused by installations or ramps – pose no problem during compaction,” explains Christoph Berndt, Construction Supervisor of the Special Coverings Group at STRABAG GmbH.
Spotlight on Safety and Precision
For maximum safety, both machines were connected to steel cables and then secured to an excavator. As soon as one machine went down the slope, the other machine was automatically pulled upwards. As well as delivering on safety, both machines also provided precise and even compaction of the special asphalt.
“Even at maximum incline, the electric rollers from Hamm do not compromise on compaction power.”
Christoph Berndt, Construction Supervisor of the Special Coverings Group at STRABAG GmbH
Follow-up Projects in the Pipeline
Both Hamm rollers made a strong impression, not only through their high compaction power, but also through their reliability in the face of extreme conditions. They also offered a far quieter means of compaction and zero local emissions “The response from all the machine operators was invariably positive. The much lower noise level even allowed drivers to speak to each other while working. When working on the slope in particular, clear communication is important. Before now, all they could do to communicate was use hand signals. Given how loud diesel rollers are, direct communication was only ever possible when the compactors were side by side or when operators shouted at each other. The fact that even the excavator (serving purely as a holding mechanism in our case) only needed to apply minimal power was good news for everyone around the construction site, since the volume level was dramatically lower.”
In light of the positive feedback, both rollers are due to be deployed in a follow-up project the customer is running in Switzerland soon.
A unanimous verdict:
The deployment on the upper reservoir demonstrated that the electric tandem rollers not only provide powerful compaction, but actually represent an optimum solution in the face of particularly challenging conditions. Another benefit: “There is less lubricant and fewer operating materials in the machine than found in conventional diesel rollers. This significantly minimizes the risk of potential environmental pollution and the knock-on effects that can bring,” explains Christoph Bernd.
Reliable Support
The STRABAG construction lead also praises the excellent support they received from Hamm. “Our contact person was on site numerous times. If ever we had problems or questions about how to operate the machines, there was always someone we could speak to, who would get things sorted for us – and fast. For instance, the braking times/delay were adjusted – Hamm was able to connect the roller to the computer on site to quickly adjust this to meet the operators’ requirements.”
Construction Tenders in Europe
In some countries, specifications regarding emissions represent an integral element of construction tenders. The fewer emissions a construction company produces, the better they are regarded in the contract assignment process. With its electric rollers, Hamm ticks the right boxes for consideration when assigning contracts. The rollers with e-drives are now available in the DACH region, central Europe, Scandinavia, and North America. These compact models have the same compaction power as their sister models with combustion engines, yet they produce zero local emissions. The electric rollers are operated in exactly the same way as the other models in the HD CompactLine series. In the electrified variant, you can choose from eight different tandem rollers – four of which feature oscillation drums. This is where the already quiet oscillation meets the quiet electric drive. The result of this is low-noise compaction machines that produce zero local emissions and cause very few vibrations in the surrounding area. They are ideal for compacting in noise-sensitive and vibration-sensitive areas, such as near hospitals or historical buildings.
The benefits of electric rollers at a glance:
