Along Europe's longest national highway, there is a 5.7 miles (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 1.2 miles (1.8 km) with a 4-lane carriageway and then over a distance of 4.6 miles (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 3.14 miles (5.04 km) along the total stretch of 5.6 miles (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 144 yd³ (110 m³) and the work progressed at  19'8" (6 m) to 32'10" (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 9'10" (3 m) 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 1000 l 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 98,097 yd³ (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 104,636 yd³ (80.000 m³) in  strength class  C40/50, 235,432 yd³ (180,000 m³)high strength concrete C 60/75 and 130,795 yd³ (100,000 m³) 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.