Job Report Cold Milling. Top job in motorway rehabilitation Wirtgen milling machines on the A99

Transcription

1 Job Report Cold Milling Top job in motorway rehabilitation Wirtgen milling machines on the A99

2 Wirtgen cold milling: Top job in motorway rehabilitation Wirtgen high-performance milling machines on the A99 The approach lane towards the Austrian cities of Salzburg and Innsbruck the A99 motorway east of Munich underwent extensive rehabilitation over a length of 4.15 km just in time for the European Football Championship 2008 hosted by Austria and Switzerland. First of all, an impressive 70,000 m 2 of asphalt pavement and hydraulically bound base layer needed to be removed by milling in just 4 days. The most powerful cold milling machines available in the market the W 2200 and W 2100 high-performance machines from Wirtgen were called for to complete this highly demanding job reliably and on time. High-performance milling machines in non-stop operation First of all, the 26 cm thick asphalt package (i.e. just under 18,000 m 3 of asphalt material) needed to be removed over the entire stretch of the motorway. In addition, the specifications called for the removal of around 13,500 m 3 of hydraulically bound base layer. Around 30,000 m 2 of the base layer material needed to be removed at a depth of 15 to 20 cm, while the remaining area was to be milled at a depth of only 10 cm. Because of the consistently high prices of raw materials and oil, both the granulated asphalt material and the hydraulically bound base layer are valuable, recyclable construction materials. That was one of the reasons for milling and loading the various asphalt layers of different quality, as well as the hydraulically bound base layer in separate operations. Maintaining the exact milling depth and thus ensuring a clean separation of the different construction materials was no problem at all for the Wirtgen high-precision automatic levelling system. Removal of the around 18,000 m 3 of asphalt and 13,500 m 3 of hydraulically bound base layer needed to be completed in just under 100 hours. This led the contracting companies to use Wirtgen W 2200 and W 2100 high-performance cold milling machines for carrying out the job. 55 trucks were in operation around the clock during the four days and nights to ensure transport of the tremendous amounts of milled material from site.

3 Use high-performance milling machines economically High-performance milling machines are the most economical machines when it comes to milling large areas on motorways, airports or industrial estates, and where continuous and unhindered operation of the machines is ensured. Especially in countries where wages and fuel prices are high, using such high-performance machines is the more economical solution for construction volumes from as little as 1,500 m 3 upwards when removing the pavement at full depth, or from 40,000 m 2 upwards when removing the surface course. In such projects, the use of smaller milling machines can involve higher operating costs per m 3 of asphalt. Major reasons for the economic efficiency of high-performance milling machines include: High-performance milling machines from Wirtgen are particularly profitable in continuous operation when supported by an efficient logistics system. 24-hour operation dispenses with warm-up times, which are always required at the beginning of work until truck transport of the milled material is running smoothly. Instead, the milling operation goes on and on and on Reduced labour cost Like the smaller 2-m machine, a high-performance milling machine is operated by a crew of two. As the job is completed in less time, labour costs per m 3 of milled material are reduced. Higher milling performance at reduced diesel consumption Putting diesel consumption into relation with milling performance shows that the high-performance machines are economical in terms of fuel consumption. Analyses have shown that they consume less diesel per cubic metre of milled material than smaller cold milling machines. Less costs for wear parts High-performance milling machines need a significantly smaller number of point-attack cutting tools than mediumclass machines. This is due to higher advance speeds, which produce less abrasion at the point-attack tool per cubic metre of milled material. High engine power ensures high advance speeds at large milling widths, making the operation of the large machines, such as the W 2100 with 522 kw (710 PS) engine shown here, highly profitable. 2// 3

4 W 2200: The world s most powerful cold milling machine Site manager Ralf Böhm (left) from Stratebau GmbH made sure that the high-performance milling machines from Wirtgen worked under optimum boundary conditions: Good communication is needed between the many companies involved and the many different project sections. That s just as important for the project s success as machine technology. Using these machines enabled the project to be completed not only within a very narrow time frame but with maximum economic efficiency as well. Why? The high-performance milling machines from the market leader impress with an extremely favourable relation of costs to milling performance especially the W 2200, which is currently the most powerful cold milling machine in the world. Good organization of trucks provided, production rates of up to 200 m 3 per hour are the rule with this machine rather than the exception. Under optimum conditions, the machine has even been able to achieve milling outputs of more than 500 m 3 per hour. The powerful machine is a leader also in terms of environmental friendliness. High-quality components and an intelligent control system not only ensure high efficiency but also Working non-stop for nearly 100 hours: Several Wirtgen W 2200 high-performance milling machines gave impressive proof of their reliability on the large construction site of Munich s orbital motorway.

5 result in an excellent energy balance. The Wirtgen formula reads: maximum milling power at minimum diesel consumption. This was demonstrated impressively yet again on the Bavarian motorway: On average, the cold milling machines consumed just 0.9 litres of diesel per cubic metre of milled material, making the high performers leaders in terms of economy. Economical operation by optimizing the milling depth On the A99, site manager Ralf Böhm from Stratebau GmbH and his milling crews demonstrated how to use the Wirtgen flagships in the best possible and therefore most profitable way. To complete milling of the huge area in record time, the 26 cm thick asphalt package was removed in two separate passes. Even though this approach involved reversing of the machines, which was very time-consuming, the overall vol- Shift change at 8 pm. Briefing takes place while the W 2100 is waiting for a truck. Logistics a key efficiency driver Even the most powerful cold milling machines cannot work economically when logistics are lacking. With insufficient truck capacity, the proportion of unproductive waiting times increases, and profitability decreases accordingly. The four large milling machines on the A99 kept as many as 55 trucks busy for 4 days and 4 nights. The tremendous performance capacity of these powerful machines needs to be considered as early as the planning stage. They load a 4-axle truck in significantly less than 3 minutes. In addition, they have a very high percentage of uptime even water can be refilled during the milling operation. The hydraulically bound base layer removed on Munich s large construction site was used again right away: Most of the material was used to produce the subgrade level for a mobile concrete mixing plant, and the remainder was stockpiled and introduced into the bottom-layer concrete later. Filling up with water during milling helped the milling crew on the A99 to avoid waiting times and ensured tremendous production rates. 4// 5

6 ume performance achieved per working hour was significantly higher because the asphalt was removed at a milling speed of 10 m/min. After that, the large machines tackled the hydraulically bound base layer at a working width of 2.20 m. It was removed at a milling depth of 20 cm and an impressive advance speed of 15 m/min, equalling a theoretical volume performance of around 400 m 3 per hour. The machine s large milling speed is also the key to profitability. Nightshift included The narrow time frame required the cold milling machines to work around the clock. No problem at all for the crews of two, as bright spotlights on the Wirtgen cold milling machines permit full visibility of the machines surroundings and critical areas even at night. Backlit control panels and Level Pro displays ensure ease of operation at the same time. Top service technicians on site fast Reliable machines are of tremendous importance. In case of an emergency, however, reliable service is no less important. The pros from Wirtgen Augsburg took care of the construction site on the A99 motorway. With its extensive network of service technicians in Bavaria and Baden-Wurttemberg, the Wirtgen Group s subsidiary in southern Germany guarantees that service personnel, armed with tools and spare parts, can be on site within the shortest possible time regardless of the time of day or night. The machines on the A99 motorway were attended to by our service technician based in Rott am Inn, not even 40 km away from the construction site. Close proximity helps us to ensure short response times, for we know that our customers are working under tremendous pressure of time, says Ulrich Städele, service manager at Wirtgen Augsburg. Bright spotlights at the upper end of the discharge conveyor ensure optimum illumination of the flow of milled material and of the truck s loading edge.

7 Met the budget, adhered to deadline And sure enough after four days and four nights, the asphalt and hydraulically bound base layer had been milled off entirely, enabling the milling crews to lash down the highperformance milling machines on their low-loaders according to schedule. We have demonstrated on this project that a professional crew, superior machine technology, good planning and efficient site logistics enable large construction projects to be executed with maximum efficiency, says site manager Böhm satisfied, summarizing the operation while Wirtgen soil stabilizers are driven onto the construction site: They are getting ready for recycling the hydraulically bound base layer A clear operating concept enables machine operators to remain focused on their work even over 12-hour shifts during the evening or night hours. Most powerful cold milling machine in the world: The Wirtgen W 2200 high-performance milling machine is best-in-class, offering a maximum milling performance of over 500 m 3 /h. 6// 7

8 Increasing productivity by optimizing the milling operation 26 cm of asphalt needed to be milled off on the A99. The W 2200 and W 2100 machines completed the job in two passes of 12 cm and 14 cm each, even though the Wirtgen high-performance machines can easily mill up to 32 cm and 35 cm deep respectively. Site manager Ralf Böhm explains the decision: The layer thickness of the asphalt package as such is not a challenge at all for the powerful machines. But large milling depths result in considerably reduced advance speeds, increased friction at the cutting tools, and thus fairly high wear and tear. Working in two passes and milling off the surface course and binder course first offers the advantage that the pavement comes off much more easily at the seam between the binder and base course layers, thus offering much less resistance to the cutting tools. In addition to that, the mixing plants prefer to receive granulated asphalt separated according to quality. Optimizing the milling depth results in reduced cutting tool wear and tear, which also means less time needed for tool replacement and more uptime for the milling operation. Profitable high-performance milling machines: The W 2200 is repositioned extremely quickly despite its impressive size and operating weight. The secret is in the machine s precise all-wheel steering, clear-cut operator s platform and user-friendly operating concept.

9 And what s equally important: The large milling machines from Wirtgen achieve their maximum milling power at milling depths of between 8 and 15 cm. Due to their powerful engines, this course of action enables us to make headway really fast. All things considered, we will have completed the job more quickly and will save diesel and cutting tools despite the need for repositioning more often and a higher total mileage. Reaching the goal in three steps: The surface of the hydraulically bound base layer can be seen in the foreground, while half of the asphalt pavement has been milled off in the central carriageway section, and in the background, the asphalt package is as yet untouched. Path of the tool in mm per cut Theoretical milling volume (bulk material) in m 3 /h Milling depth 50 mm Tool path in mm per cut Theoretical milling volume in m 3 /h Milling depth 150 mm Milling depth in mm The milling depth selected has an immediate effect on the milling performance and on the wear of tools and toolholders. At a milling depth of 100 to 150 mm, Wirtgen large milling machines achieve the highest volume output of milled material at the lowest costs of wear and tear. Milling depth 300 mm The milling profiles of the cutting tools and therefore the chip sizes of the milled material vary significantly at different milling depths. When the specified milling depth exceeds 200 mm, it can indeed be worthwhile to mill in several machine passes. 8// 9

10 Carriageway closure and tight schedule minimize traffic disruptions Used by around 110,000 vehicles per day, the A99 motorway leading from Munich towards Salzburg is one of the most heavily trafficked roads in all of Germany. Between the junction at Hohenbrunn and the München- Süd intersection, the 3-lane and 4-lane asphalt carriageway was finished, as a representative of the Hohenbrunn motorway maintenance depot put it. To keep the duration of traffic disruptions caused by the rehabilitation of the 4.15 km long section as short as possible, the motorway authority for southern Bavaria decided to close the entire carriageway to traffic. The time schedule was correspondingly ambitious: The upper pavement layers were removed, the frost blanket was recycled, and an asphalt base layer and concrete surface course were placed in just two months. A huge program with tight deadlines that posed a challenge to all of the various project sections. Incidentally, powerful machines from the Wirtgen Group were part of the team also in the remaining project phases: In addition to the milling machines, soil stabilizers from Wirtgen, asphalt pavers from Vögele and rollers from Hamm were in operation on the project as well. Full closure of the carriageway gave cold milling machines and trucks the room they needed for milling and manoeuvring and for unimpeded transport of the milled material from site.

11 Coming out for the final round: After three days of non-stop operation, the large milling machines begin removing the hydraulically bound base layer at a depth of 20 cm. 671 kw (913 PS) enable the W 2200 to complete the job quickly at 15 metres per minute or 200 m 3 of milled material per hour. 10 // 11

12 Illustrations are non-binding and may include customized fittings. Subject to technical changes. Performance data depend on operational conditions. No EN-08/08 by Wirtgen GmbH Printed in Germany Wirtgen GmbH Reinhard-Wirtgen-Strasse Windhagen Germany Phone: +49 (0) / Fax: +49 (0) / Internet: info@wirtgen.com