surface profile milling using the trimble 3d controller working on

By Jeff Winke

Trimble 3D Surface Profile Milling on Hamburg-to-Bremen

A1 Motorway project

German Roadwork Benefits from Technology

T he German Federal Government has made a strong commitment to improve its motorway

infrastructure. There are four pilot projects known as “A-Models” which forge innovative long-term partnerships between the public and private sectors.

Under the arrangement, private con-tractors provide and finance the costs to build, rehab, operate, and maintain

the motorway for a 30-year contract. In return, the private contractors receive a monthly share of the tolls collected on heavy-goods vehicles collected by government for that relative section of the motorway under the contract.

One such project is the widening of the heavily-used A1 Hamburg to Bremen Motorway, which requires an investment of approximately EUR

Surface profile milling using the Trimble 3D Controller working on the A1 Hamburg-Bremen Motorway to follow a detailed, digital plan.

Displayed with permission • Machine Control Magazine • Vol. 2 No. 2 • Copyright 2012 Spatial Media • www.machinecontrolonline.com

650 million ($868.6 million US) A consortium called A1 mobil was formed for the A1 Motorway project. A1 mobil is comprised of Bilfinger Berger Project Investments GmbH Inc., the British infrastructure developer and operator John Laing Infrastructure Ltd., and Johann Bunte Bauunternehmung GmbH & Co. KG Inc. & Ltd. Partnership. The Federal Republic of Germany, represented by the Federal State of Lower Saxony, is the developer for this project.

ARGE A1 Hamburg-Bremen, the contractor in charge of the widening from the current four lanes to six lanes

between the ‘Buchholzer Dreieck’ junction and the ‘Bremer Kreuz’ junction, began working on the project in August 2008. All work is expected to be completed by end of year 2012.

The 73-kilometer project has been divided into 26 work sections. Each section is approximately six kilometers. Adjacent sections will be widened at different intervals so that any given time there will be a construction-free section of motorway between the two sections simultaneously under construction. This is intended to avoid excessively long stretches of construction, thereby improving traffic safety.

The road plan specifications call for the new lanes to be constructed with a combination of asphalt and concrete surfaces. The top wear-and-tear surface of the highway is to be removed over the entire project to a four-centimeter depth. In addition, gradient optimization is to be carried out over the full section and the cross-section adapted to the regula-tory standardization with a camber of at least 2.5%. Sub-soil examination revealed that large parts of the existing roadbed substrate are still viable.

The question facing ARGE A1 was whether to remove the road entirely and rebuild it completely, or retain use

Sven Ungnade, ABS machine operator, sets up the Trimble SPS930 Universal Total Station.


those parts of the roadbed substrate that are still stable? In other words, is it economically and technically feasible to use the stable substrate?

“We decided to reuse existing mate-rial, in order to save on expensive new material and also to have less old mate-rial to remove and recycle. Of course, the time we’d save was also an important factor,” stated ARGE A1 substrate coordinator Achim Huebschmann.

The challenge: flexibly adapt the milling depth to the various existing substrate conditions and surface profile changes. This required a detailed milling plan. ARGE A1 surveyors re-surveyed the entire roadway, employ-ing three terrestrial points within a 10-metre grid of each point. The points surveyed were placed in CAD software and converted to a Microsoft Excel output. The output maps illustrate the milling depths of the entire highway in five-centimetre stages shown in colour shades or in a numerical table.

The issue then became how to ensure that the milling equipment accurately follows the milling plan. The traditional approach would be to paint the points onto the road surface at five-meter inter-vals. To do that, ARGE A1 would incur huge surveying costs, plus the potential for errors with this manual system.

ABS Asphalt Beton Service GmbH & Co. KG , the subcontractor for milling, offered a solution. “We knew that the advanced technology of an automatic 3D control system on our Wirtgen W2100 milling equipment could help us achieve the accuracy and results we needed,” says Wolfgang

ABS machine operator, Sven Ungnade checks the milling results.


Schmidt-Legahn, general manager at ABS. ”The design data on the drawing board is transferred directly to the on-board computer of the milling equipment, meaning the operator can complete the complex milling plan automatically, without resorting to tape measures, tracing pegs and highway markings.”

To test this new technology in opera-tion, Schmidt-Legahn decided to rent the equipment. The systems of three manufacturers were tested. Only the Trimble® GCS900 Grade Control System with the SPS930 Universal Total Station satisfied the demands for accuracy, speed, and local dealer support. With GCS900 on a milling machine, surfaces can be milled at variable depth and slope without stringlines. “Controlling the precise cutting depth of mill minimizes over-cutting, creates a smoother surface for paving and a higher smoothness index of the finished road,” Schmidt-Legahn says. “Productivity is increased by efficient milling already in the first pass without setup of references like stringlines.”

The components of the Trimble 3D Milling System are the SPS930 Universal Total Station, one MT900 active tracking target and one CB430 Control Box. The UTS automatically tracks the MT900 target fixed to the milling drum continuously measuring its nominal position and transmitting it to the Trimble CB430 Control Box mounted on the milling machine.

The CB430 Control Box uses the design data to calculate the necessary milling depth, and controls the hydrau-lics accordingly, so that the milling operation is performed automatically in accordance with the roadway-milling plan. No highway markings are needed. The milling equipment follows the

specified milling plan. The milling speed is 15 metres per minute. Daily milling volumes on the job averaged 5000- to 6500-square meters, at depths that range between four and 30 centimeters.

“The Trimble GCS900 Grade Control System was simple to use,” states Hans-Hermann Roblick, ABS construction site manager. “The milling equipment operates automatically, we just have to monitor the results which fall within a tolerance of +/- 5 millimeters.”

Roblick points out that the local Trimble distributor, Eilers & Droste, provided thorough training to the two machine operators, Mark Reinecke and Sven Ungnade, which helped to ensure success with the new system.

Ungnade checks the milling depth, “Right from the start, it was an error-free operation, which is confirmed daily because the milling results are checked by an independent surveyor.” Ungnade had also commented that he found it easy to set up the Trimble Universal

Total Station, without having a survey-ing background.

ARGE A1 and the sub-contractor ABS Asphalt Beton Service GmbH & Co. KG incare both agreed that surface profile milling using a Trimble 3D system has helped achieve the complex milling profile and accuracy required over the cross-section and longitudinal sections of the highway. Reported savings of approximately 7,000 tons of material per section of construction—with the average price of 50€ per ton of material—means that the investment costs for the Trimble technology has been recouped.

A project of this scale, carried out under difficult conditions, is truly one that benefited from the use of Trimble construction technology. MC

Jeff Winke is a business and construction writer based in Milwaukee, Wis., USA. He can be reached through www.jeffwinke.com.

Achim Huebschmann, the ARGE A1 substrate coordinator, explains the milling plan.


surface profile milling using the trimble 3d controller working on

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