Wirtgen Group technologies in construction of the Transylvanian "Autostrada A3" motorway in Romania
A3 infrastructure project to link Bucharest with Hungary
The construction of the A3 – the Transylvanian motorway – was given the green light in 2004. Once completed, the A3 will link Bucharest with the Hungarian border over a stretch of 588 km, extending across Romania.
The route stretches from Bucharest via Ploieşti, Braşov, Sighişoara, Târgu Mureş, Cluj-Napoca, Zalau and Oradea to the Hungarian border, where it will ultimately connect to the Hungarian M4 motorway. Completion is scheduled for 2017.
Wirtgen Group technologies for the Bucharest - Ploieşti segment
Contracts for the 62-km section from Bucharest to Ploieşti were awarded in roughly equal shares to two different consortiums: Impressa Pizzarotti / Tirrena Scavi for the section from Bucharest to Moara Vlăsiei, and Spedition UMB /Pa&Co International / Euroconstruct’98/Com-Axa for the Moara Vlăsiei to Ploieşti section.
Spedition UMB is a member of the UMB Group owned by Dorinel Umbrarescu – known as Romania's "Asphalt King". As the general contractor, it opted for technological solutions from the Wirtgen Group for all construction phases, from the foundation and soil stabilization, paving and compacting of asphalt, all the way to constructing the adjoining concrete elements, such as gutters and curbs. All told, 35 machines from the Wirtgen Group were used for construction of the A3, as many as twenty of which were used on the final segment from the 48th to the 62nd kilometre.
Experience from Tirschenreuth for the foundation: HCQ and Hammtronic
Six Hamm Type 3520 vibratory compactors, each weighing 20 t, were used for the foundation. These compacted the soil in two groups of three machines operating in echelon. The compactors were equipped with HCQ compression meters. These check the degree of compaction during the work and directly indicate any corrections that may be necessary.
All compactors were also equipped with the Hammtronic microprocessor control system. This smart technology optimizes machine functions, ensuring economical use of consumables, optimum compaction results and maximum safety. Hammtronic monitors all engine and machine functions, in particular travel drive, vibration, oscillation and engine speed. This boosted productivity while simultaneously reducing fuel consumption by 30 to 40%.
And thanks to their VIO drums, some of the compactors were even able to switch from vibration to oscillation at the press of a button without stopping.
Reliability is crucial for soil stabilization
Soil stabilization was carried out in-situ by a machine set comprising an SW 16 TA binding agent spreader, Wirtgen WR 2500 S recycler and Hamm 3518 compactor with an operating weight of 18 t. In a first step, the SW 16 TA spreads the binding agent in the exact quantity and composition specified according to the soil samples.
Next, the Wirtgen WR 2500 S processes the soil with the binding agent to form a homogeneous load-bearing mixture, together with cement and water from the connected tanker. Mixing the binding agent into the soil reduces the soil's water content, improving its paving properties, compactibility and load-bearing capacity.
Depending on local conditions, the machine set can stabilize soil with the addition of 2 to 5% binding agent across a width of 2.5 m and down to a maximum depth of 50 cm at a speed of up to 25 m/min. Not only is the Wirtgen WR 2500 S equipped with a milling and mixing rotor with four milling speeds, but it can also switch between the up-cutting and down-cutting process without the need for conversion, allowing precise control of the final granulated material.
The processed soil was then pre-compacted in two or three passes and the final compaction stage subsequently completed by a Hamm 3518 vibratory compactor with oscillation and the HCQ system.
The solution for optimal asphalt paving: Vögele pavers with NIVELTRONIC Plus and Big-MultiPlex Ski
UMB Spedition used two Vögele pavers for the asphalt paving work: a Vögele Super 1900-2 with AB 600-2 TV screed with a pave width of 7.5 m, and a Vögele Super 2100-2 equipped with the same screed, but extended to a maximum pave width of 9 m.
The first asphalt layer was levelled with the aid of Vögele Niveltronic Plus. This automatic grade and slope control system allows the grade to be precisely controlled across the entire section by tracking a specific reference. This ensures that the specified grade is achieved with pin-point precision, regardless of the substrate level.
A Big-MultiPlex Ski was also used for the additional layers. Virtual scanning with three ultrasonic sensors meant that it was not necessary to set up stringlines. This eliminated both the need to constantly reposition stringlines and problems resulting from incorrect positioning choices.
Hamm compactors first choice for final compaction
Several Hamm GRW 15 rubber-wheeled rollers (operating weight 12 t, maximum weight 24 t) and DV 90 VV oscillation rollers with an operating weight of 9.6 t were employed for the final compaction stage (from a minimum value of 85% to a final value of 98%).
In addition to their standard equipment complement, the GRW 15s were also fitted with isothermal aprons and tyre heating to prevent bitumen from sticking to the machines.
A key feature of the DV 90 VV oscillation roller with the intelligent Hammtronic management system is the electronic control system that infinitely adjusts the speed and oscillation frequency to the surface being compacted. It also features a panoramic cabin in which the seat and control cockpit can be automatically rotated through 360°, ensuring that the operator can always sit facing the direction of travel.
The width of the surface compacted in one pass was increased from 1,680 mm to 2,990 mm by using two DV 90 VV driving in echelon.
SP 250 – A Wirtgen all-rounder for concrete paving
To create the adjoining concrete elements (canals, gutters, curbs), UMB Spedition used a proven all-rounder from the Wirtgen Group – a Wirtgen Type SP 250 slipform paver with a multifunctional configuration and flexible application possibilities for all job site needs. This slipform paver can be operated with four or alternatively three crawler tracks in both offset and inset modes, with numerous moulds in fixed or variable sizes.
For this application, UMB Spedition adjusted the configuration so that the SP 250 could lay down both the sand base course and the concrete in the specified profile. This resulted in a substantial increase in productivity and a high-quality canal profile.
In order to install gutters in the motorway's central reservation and at bridge ramps, UMB Spedition used a Wirtgen W 100 F wheeled milling machine with a milling width of 1 m and a front-loading conveyor that milled out a canal 300 mm deep and 1,000 mm wide. Completion of the gutters was then handled by the SP 250, which laid down a sand base course and concrete surface course.
Upon completion, a maximum speed of 100 km/h will be permitted on the new two-lane A3.