German company uses lase rbased machine control solution for the construction of a football field near Munich.
SchÀftlarn-Ebenhausen is located 16 miles south of Munich, Germany, in the beautiful Isar valley. It is one of the emerging communities in the prospering area around the Bavarian capital.
SchÀftlarn e.V. 1921, the local Sports Club is a modern facility, which can only perform successfully by offering a certain degree of quality. The Club thus decided to have an official football training ground built adjacent to the main playing field. A CAT dozer equipped with the automatic Trimble BladePro® Machine Control System was used to build the football field. The renowned Baumann engineering office, based in Hausheim, was entrusted with the project planning. The field has a gradient of 0.6% and 0.7%. A trickle-irrigated weep-hole subbase allows for better drainage. No compromises were made regarding the quality of the reinforced layers and the quality of the rolled turf, which was provided by the Schwab company based in Waidhofen, near Ingolstadt. Soil compaction was a major concern, as the standard-size B-field needs to be playable at all times and to dry off quickly after showers. The trucks delivered the construction material on a predetermined access way, in order to avoid soil compaction during construction.
Holzer Civil Engineering, a company located in the neighbouring village of Degerndorf, was awarded the construction of the 94 x 62 m football field, a Beach Volleyball ground and a skate park. The family business, now run by Peter and Othmar Holzer, was founded in 1960 and has now approximately 75 employees and an annual turnover of about 9 million Euro. Their brother Konrad Holzer is the company’s construction supervisor.
Apart from earthworks, road construction and pipe works the company’s service portfolio also comprises, exterior construction, garden and landscape design and pavement works for clients from the greater Munich area to Garmisch-Partenkirchen and from Ammersee
to Rosenheim. A container service and a building material business complement the company’s comprehensive offerings.
The new playing field was built with reinforced soil, which means that the building materials – topsoil, cohesive soil, non cohesive material (clay and gravel) – were reintegrated in the sub-base layer to the best possible extent. About 7,800 cubic meters (2 acres) of soil had to be moved for the project. The contract was awarded on April 8, 2003 and construction began on April 16, 2003. First the humus layers, which had a variable depth, were removed. Afterwards, the sub-base was filled and the modelling of the terrain with the available construction material began.
A CAT 053 Caterpillar dozer with manual Trimble laser control and broad chains was used to keep soil compaction to a minimum. Bad weather tightens tough schedule The modelled terrain blends well with the hilly countryside around Munich – one of the specialties of dozer operator Walter Zwick. The dozer operator started working for the Holzer company in 1968. He has been operating dozers for 35 years and modelled a lot of sophisticated landscapes and terrains. Walter Zwick experience that in the construction business not everything always goes according to plan.
During the project the earthworks were often interrupted by bad weather periods, including massive hail leading construction supervisor Konrad Holzer to be concerned that he would be unable to complete the work in time for the delivery of 5,800 square metres of rolled turf, ordered to arrive on site on May 26 to be installed by the Club members. But to Konrad’s surprise, fine grading of the reinforced soil and installation of the three different layers of humus, sand filter layer and turf sub-base were done by 23 May in 7 working days; ready just in time for the arrival of the turf.
Smooth finish – layer after layer
For these fine grading jobs a D4H dozer was equipped on site with the BladePro machine control system from Trimble, including two laser receivers and a cross-slope sensor at the blade. The machine featured a flexible 6-way blade and low ground pressure tracks to minimize soil compaction. A rear-mounted ripper additionally compensated for any soil compression. In combination with a traditional rotating laser transmitter, the machine control system guarantees automatic blade control with each pass.
Easy Soil Distribution
The company was able to use some existing equipment for the project, such as the 1145 dual slope laser transmitter from Spectra Precision (now part of Trimble). Setting up the laser transmitter went like clockwork, as the workers were familiar with the instrument. Sometimes experienced machine operators have problems switching from manual systems to automated machine control. Sixty-year-old Walter Zwick, however, had absolutely no problems with the system after a short training period.
Walter Zwick commented, ”The automated system is easy on your eyes, as you don’t have to permanently control the design elevation. Above all, I can now concentrate on distributing the material. Even small volumes – which are difficult to move manually with the blade – can be positioned more easily with each pass using the laser-based control. The orientation of the dozer does not have to be monitored. I can quickly level out any bumps or leftovers.
“Compared to the manual control, I can finish the surface approximately twice as fast with this system”.
”The smoothness of the surface and the precise installation of the individual layers are essential for sports grounds construction. The laser beam provides an exact reference and allows for spotting any settlements right from the start, which can be levelled out subsequently with each pass. Also, we are no longer dependent on the weather conditions as much as we used to. Rough patches in the humus layer, which occur especially after showers, can be levelled out very easily. If a finished surface is damaged by hail, Walter Zwick just does a few more passes and eliminates any dents. During fine grading, we achieve an accuracy of ±1 cm (0.4 inches).”
His brother Othmar Holzer, the company’s managing director, is happy with the new system,
”We construction industry we are rarely able to manage precisely with the material quantity calculated. Usually we need 5 to 10% more material. However, this time due to the precise installation of the various sub-base layers, we exactly met the tightly calculated volume of 960 tons. Each additional ton costs about 30 Euro, so the system pays off quickly. With the Trimble BladePro system we neither have to position any stakes nor do we have to do manual grade checks and as far as site survey is concerned, we save the costs for one or two skilled construction workers. After the construction of 3 to 4 football fields, the system will pay for itself.”
The construction of the football field was completed on schedule on May 23, 2003. The layers were precisely installed with the correct depth. After the construction works were completed, the rolled turf was installed on May 26-28 by the SchÀftlarn Sports Club members.
Project data:
Earthworks for:
• 94 m x 62 m football field
• beach volleyball ground
• skate park
Time: April 16 – May 28, 2003
Total cost: ca. 370,000 Euro
Material moved: 7,800 m3
Reinforced soil: Topsoil, cohesive soil, non-cohesive material (clay and gravel)
Earthworks schedule:
April 16 to May 14:
Topsoil removal, sub-base and terrain modelling (banks) using a CAT053 dozer with manual laser control.
May 15 to May 23:
Fine grading of reinforced soil and installation of 3 different material layers:
• Humus: 5 cm (2”)
• Sandfilter layer: 5 cm (2”)
• Lawn sub-base: 10 cm (4”)
using CAT D4H dozer with tiltangle blade (6-way-blade) and broad chains. Controlled by BladePro automatic dual laser control system including
blade slope sensor.
May 26 to 28
Installation of rolled turf by Club members
Benefits of BladePro System:
• Fine grading accuracy: < 1cm (0.4”)
• Grader accuracy achieved with dozer
• Material volume met exactly as calculated.