Tunneling, Mediterranean Highway, Spain

Along Europe's longest national highway, there is a 9.1 km section between La Herradura and Taramay that connects the cities of Cádiz and Gibraltar in the South  of  the  Iberian  Pensinsula  and Barcelona in the North East.

It runs over a distance of 1.8 km with a 4-lane carriageway and then over a distance of 7.3 km in each direction of traffic as a separate route through three twin-bore tunnels and four bridges.

The Challenge

• Shotcreting on Europe’s most high ticket roadway.
   
• Backing up advance work in each of the three twin-bore tunnels in a length of 5.04 km along the total stretch of 9 km.

The Solution

The bridges consisted of two parallel girders but the tunnels in each direction of traffic  were designed  as single structures. All of the six bores had a full section of approximately 110 m³ and the work progressed at  6 to 10 m per day, depending on whether the supporting arches type THN 21 and THN 29 needed to be installed or not.

The three mobile shotcrete Sika®-PM500 P spraying devices were first used to secure the slope area around the portals and then to secure the tunnel excavation work according to the new Austrian tunnel construction process.

The 4 wheel drive and 4 wheel steering machines easily maneuvered through the challenging terrain and showed off their incredible resilience in this project.

The horizontal automatic  system on  the  spraying  arm  of the Sika®-PM500 P proved to be very helpful in the shotcreting work in the six LA HERRADURA tunnel bores. This device enabled the cradle to be extended by 3m and held in a horizontal position. In conjunction with the highly maneuverable head of the spraying nozzle. This resulted in an extraordinarily even spray pattern with little rebound.

All of the Sika®-PM500 used at the LA HERRADURA site were equipped with a liquid metering device (Sika®Aliva-403,5) and one or two tanks for concrete acceleration (of a capacity 1.000l each). As the site already provided compressed air lines in the tunnels, the spraying devices were not supplied with their own compressors. A total volume of 75,000 m³  of shotcrete was placed in the six tunnels.

While pumping of concrete for the tunnels as well, there was a monopoly of Putzmeister machinery.  Approximately 80.000m³ in  strength class  C40/50, 180,000 m³ high strength concrete C 60/75 and 100,000m³  in strength class  C25/30  was  placed using stationary concrete pumps, which had been previously used for building the bridge piers.

The section was initially built by U.T.E. LA HERRADURA, a joint venture comprising of the construction companies PLODER S.A., AZVI S.A. and OBRAS SUBTERRÁNEAS S.A.

Concrete Takeaways 

• The project commissioners, the Ministerio de Fomento, had initially calculated construction costs totalling €180 million for the complex track routing. This amounted to €20 million for each kilometre, making it the highest motorway costs in the whole of Europe.
   
• The Sika®-PM500 P had an extensive working reach and was very well suited for shotcreting jobs on high embankments as well as in underground chambers and tunnels and were a crucial part of this project.

Project Partners

The section was initially built by U.T.E. LA HERRADURA, a joint venture comprising of the construction companies PLODER S.A., AZVI S.A. and OBRAS SUBTERRÁNEAS S.A.