On 17 July, after just eight months of tunnelling, Herrenknecht’s 15.2m diameter ‘Mega’ EPBM broke through on its 3.65km long North Tunnel drive for Madrid’s M30 southern link project, in Spain (T&TI June, p23), three months ahead of schedule.
Believed to be the world’s largest EPBM, the machine has achieved impressive advance rates through Madrid clay and gypsum since its launch on 10 November 2005. During the best production month of May, with an overall advance of approximately 760m, the Acciona Infraestructuras/Ferrovial Agroman JV were regularly achieving rates of up to 15 rings per day.
Further daily progress was somewhat limited by logistics, with over 500 trucks per day entering the small motorway-based site to service the TBM and remove the 500m3 spoil generated by each ring of advance.
Settlement along the alignment has been minimal and the passing of sensitive structures such as Metro Line 1, with 2-3m clearance, proceeded without incident.
Professor Manuel Melis, coordinator general of infrastructure for the city of Madrid, was obviously delighted with the machine’s performance when T&TI visited the site shortly before the breakthrough. He is now keen to see how the MHI-Duro Felguera EPBM, which was launched in April of this year on the South Tunnel by the FCC/Dragados JV, performs in comparison.
