First Austrian PPP road project uses GPS

Equipment from Trimble is being used in the construction of the southern segment of the A5 Northern Motorway, north of Vienna, where the S1 and S2 motorways ('Ypsilon') branches are being built.

The first Austrian Private Public Partnership (PPP) road project, consists of 51,5 km of road, comprising four separate road sections, the A5 South, S1 West, S1 East and the S2. The roads, which connect to form a Y-shape, are the main commuter corridors between Schrick and Vienna.

A total of 9 million m³ of earth has to be moved, 390000 tonnes of asphalt laid and 1,6 million m³ of concrete and 87000 tonnes of reinforced concrete will be used.

The Bonaventura Straßenerrichtungs GmbH (a Hochtief-ALPINE-Egis Consortium) was awarded the contract for the planning, financing, construction and operation of the first section of the A5 autobahn.

Trimble is providing its GPS systems for design, grading and checking purposes.

Trimble's SPS780 receivers and TSC2 data collectors were used to measure a surface model of the entire project and interrogate it prior to grading. This helped avoid potential design problems and enabled site workers to look for best routes and solutions to environmentally challenging areas.

Michael Pretzler, who heads up the surveying and machine control operations for the consortium, estimated that five survey teams and 200000 stakes will be required for the whole project. However, he said without using the GPS technology the number of surveyors needed would have been doubled. The final design files are transferred to the machines equipped with grade control systems, thereby reducing the need for construction staking.

The survey teams continuously check and verify finished grade and material thickness in real-time. They can provide in-field checking and reporting and confirmation of the end of the project in a few months time.

A total of eight excavators, nine dozers and 14 graders have the Trimble grade control systems on board. Significant reductions in staff and materials and improved safety and accuracy are expected on the section of road, where nearly 200 pieces of equipment and around 1000 staff are employed.

GPS grade control systems are fitted to excavators and dozers. GPS antennas are mounted on the back of the excavator or on the dozer blade to identify the position of the machine and blade/bucket, and to put the design surfaces, grades and alignments inside the cab, at the fingertips of the driver.

This allows the operator to perform bulk earthworks and mass excavation quickly in a stakeless environment. With the GCS900 grade control system for excavators the machine operator can build noise protection walls or embankments without strings, stakes and plans.

Final and precise grading work is carried out using the GCS900 grade control system with the SPS930 Universal total station, as this combination provides millimetre level accuracy, according to Trimble.

The UTS robotic total station tracks the target mounted on the blade of the machine and continuously measures the target's position to transmit the data to the in-cab computer. This then determines the desired elevation and slope for that position.

The contracting agency, Autobahnen und Schnellstraßen-Finanzierungs Aktiengesellschaft (ASFINAG) - the Austrian government agency responsible for roads - will pay costs of almost € 1 billion following project completion.

The 32- year concession project involves the funding, design, construction, operation and maintenance of the new dual carriageway, a number of noise reduction structures, three cut-and-cover tunnels, one 1,4 km long bored tunnel (with cut and cover approach tunnels), approximately 74 other structures, and two service stations.

The A5 has been under construction since February 2007 and forms part of the EU-TEN (European Union Trans-European Network) project.

In addition to forming an integral part of the Vienna ring road, Ypsilon will result in the only motorway to connect Vienna and East Austria to the Czech Republic and beyond, thereby marking an important stage in the expansion of the infrastructure towards the new EU Member States.