Wirtgen Slipform Paver SP 25i with AutoPilot Field Rover
In the past, stringlines always had to be set up expensively and time-consumingly for the construction of concrete sections. These caused obstructions during installation and had to be removed again at the end of the project. Those days are now over because the AutoPilot from Wirtgen with Field Rover heralds a new era. The satellite-aided navigation system controls the steering and cross slope of the slipform paver fully automatically – without the effort of creating a digital terrain model.
Wirtgen AutoPilot Field Rover receives bauma Innovation Award 2013
Martin Datzert knows the possibilities of the system because, together with the Wirtgen GmbH developers team, he supervised construction sites at which the AutoPilot and Field Rover were in operation immediately before its market launch. The following two examples show that installation without stringlines works even under different basic conditions. These range from a three meter wide road surface for a cycle path to the concrete protection wall on a freeway.
3,500 meters of perfection without a stringline
In February 2013, VSB infra GmbH & Co. KG, Dortmund, became the first German company to buy an SP 25i with AutoPilot. Managing Director Kay Petersen and his team have thoroughly tested the new technology in advance, in the construction of a 3.5 kilometer long concrete protection wall on the A7 freeway near Bockenem among other projects. The 90 centimeter high wall with step profile was built parallel to the new road surface. VSB infra completely dispended with the use of stringlines.
Instead, construction manager Thorsten Kräutner recorded measuring points at intervals of 20 meters with the Field Rover a few days before beginning construction.
"The recorded data can be viewed on the Field Rover display and re-edited if necessary," the developer and survey engineer Matthias Fritz from Wirtgen GmbH adds. "When everything is perfect, you transfer the data from the Field Rover to the slipform paver by USB stick."
Enormous time saving
"The big advantage of this method is that there is no stringline to obstruct the team around the paver. The concrete mixers also have more room to maneuver. This makes the work much easier and quicker," says Dipl.-Ing. Petersen as he recalls his first experiences with the new system. But for him, other aspects are also relevant: "The time for setting the lines is saved. This is noticeable above all for radii, for example at roundabouts. The points are recorded with the Field Rover in no time at all – not like before where the surveying and setting of the lines took just as much time as the construction." The data recording is particularly fast when the concrete profile is to be built on existing road sides. The user can then record the data on site and transfer them to the paver within minutes.
Goodbye to trip hazards
Böhling Bauunternehmen GmbH in Friedeburg in Northern Germany used the system in Bosse at the southern perimeter of the Lüneburg Heath. Here, a three meter wide dyke path was constructed along the river Aller with various slopes, bends with slight elevations and long straights. One day before beginning construction, Wirtgen specialist Matthias Fritz together with Franck Alberts, foreman at Böhling, went along the track and recorded about 60 measuring points along the two kilometer long stretch with the Field Rover. "A certain preparation time is necessary even with the Field Rover but it is much quicker and less personnel-intensive than all the other available methods," Martin Datzert knows.
As soon as the data are transferred to the paver and the SP 25i is installing the concrete profile, it constantly compares the current position with the nominal data.
At a reference station set up at the side of the construction site the paver receives a DGPS signal which gives the position precisely with an accuracy of one centimeter. The paver control system generates the steering signals from the differences between the nominal and actual data. The driver no longer has to intervene.
On this principle the AutoPilot also took over the control of steering and cross slope on the construction site in Bosse – even in the bends. Machine operator Torsten Fabricius always had the position and the current parameters in view on the display but was able to concentrate totally on the coordination with the concrete mixer and his colleagues on the ground. They, on the other hand, appreciated being able to work without stringlines as did the drivers of the concrete mixers.
Sensors for height adjustment
While the AutoPilot steers, the height adjustment is controlled by an additional sensor. This may be an ultrasound sensor or a ski sensor, a laser receiver or a total station depending on the nature of the ground and the local topography. A laser sensor was used on the dyke path construction site. A different story on the freeway construction site: VSB infra scanned the new road surface with an ultrasound sensor – an ideal reference.
Convincing new paver generation
When testing the AutoPilot, VSB infra GmbH & Co. KG and Böhling Bauunternehmen GmbH were also able to judge the new SP 25i. Managing Director Egon Böhling especially praised the new, very accurate steering and the many sophisticated details. Managing Director Kay Petersen was thrilled with the convenient operation of the slipform paver, its high transport and maneuvering speed and the economical engine concept. These were just some of his reasons for deciding to buy a machine immediately after the tests. VSB infra is therefore the first company in Germany to use the AutoPilot and, as Petersen says, "the system convinced me one hundred percent."
With the purchase of the machine, Wirtgen trainers provided AutoPilot training for the entire construction team of VSB infra Kay Petersen knows why: "It is not just the construction managers, who will record the data with the Field Rover later, who need to be familiar with the system. The foremen and machine operators also have to know how the AutoPilot works and what it can do. When that is the case, we can exploit all the economical advantages and produce optimum quality."