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Why Europe’s Largest Ports Believes in mmGPS From Topcon
The Port of Marseille-Fos in South France is only second to its Normandy based counterpart Le Havre and is attempting to double its container handling capacity, which in 2010 exceeded one million units! The port has given the site extension the name 2XL. For five months, teams from Eurovia Mediterranean (Vinci Group) worked hard to level the 400,000 m² work site, and the construction of the new pavement has just been completed. “When the teams first arrived on site, the terrain was far from level… The entire site showed quite large differences in structure,” explains Frédéric Matrat, supervisor at Eurovia Mediterranean, “to implement the 125,000 m³ of compacted concrete road, a thickness between 20 and 38 cm, and the mix of 6 cm thick, we had to shave and reshape some areas with 40,000 m³ of untreated gravels to stick to the substrate.” To do so, officials from Eurovia Mediterranean opted for machine control technology which is amongst the most advanced on the market today… Topcon's Millimetre GPS (mmGPS) system. “As we were dealing with large masses and had to work on a large area (width of 800 m), the 3D machine control system, with the laser corrected height data, has very quickly established itself to us,” Frederick Matrat advised. Therefore a 2100 Wirtgen planer, two Volvo G930 motor graders and a Caterpillar 120 M were equipped with mmGPS.
GNSS – GPS and GLONASS
Developed by Topcon around 2004, mmGPS is gradually resonating among the French labourers. “Even if it leads to changes in some habits, our system is more than most customers in the maturing market,” says Yves Herrada, division manager at Topcon Positioning France. At Fos-sur-Mer, Topcon technology has been favoured by Eurovia for its ease of use. As explained by Thierry Roux, regional manager for Aix-en-Provence: “Combining a laser transmitter with the GNSS system enables multiple machines to work at once, as well as allowing similar equipped surveyors to carry out tasks in the same working area, all receiving the same accuracy level to less than one centimetre. This solution allowed us to free ourselves from the traditional way of working, with each machine or surveyor using a dedicated total station. With this Topcon system, all equipment in the working area are on the same basis, without loss of signal”.
“In total, we had one GNSS base unit for the entire site, and four mmGPS lasers to cover 1.5 km length”. Roux continued “These lasers were easily installed by site personnel - the foreman or machine operators. Machines went from one laser to another without any communication interruption allowing infinite adjustment with an optimised daily output. The technical advantages of the system developed by the Japanese group are numerous”.
Among them is the LazerZone technology, which is the real heart of the mmGPS system. Unlike the traditional plane of a laser, it emits over a radius of more than 300 m, a beam at 360° to an elevation of 10 m. “We installed the laser at a height of 1.6 m on top of a solid concrete block that was designed specifically for the site to serve mmGPS,” says the manager. Another plus was that the Topcon system benefits from using both the Amerian GPS satellite and Russian GLONASS satellite systems making it incredibly efficient. “This system certainly brings a realistic alternative for traditional 3D control,” says Thierry Roux.
To control the different stages of the project, surveyors equipped with pole based mmGPS equipment measured work done by machinery to an accuracy of less than one centimetre. After using the system for five months, the system has brought delighted votes from the site crews. “While we were asked a tolerance of ± 2 cm, we actually obtained ± 1 cm on guided walks,” explains Frederick Matrat. He continues “Out of 500 core sampling tests, only two showed a sub-thickness… the laboratory was amazed!” The fantastic results obtained on site by Eurovia Mediterranean, has also lead the company to use the same process on other major projects in the region, for instance the Grand Stade Nice, A50.
The construction of this 2XL project also illustrates a new strategy for Topcon France; now working with a number of major accounts. Taking advantage of an internal reorganization, the French subsidiary of the Topcon Europe Positioning is now working with many large groups in the construction business. “Our aim is to be a strong partner for our customers who can rely on our expanding experience in the execution of important projects such as this”, says Gael Basseville, responsible Topcon machine control in France, “More than just products, we bring our expertise and methodological assistance to implement the right system at the right place”.
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