The history of a tunnel boring machine (TBM) currently in use for road construction in Poland demonstrates that rebuilding has no age limits. The EPB Shield first began its journey in 2005 in Madrid, Spain, where it excavated a tunnel for the M-30 inner ring road. After completing the project, the machine was put on hold for more than 15 years. However, since the summer of 2022, its story has continued with a new challenge: constructing two tunnels, each 2,258 meters long, for the new S19 expressway between Rzeszów and Babica in Poland.
Originally the world's largest TBM of its time, the machine was owned by contractor Acciona since its deployment in Madrid (2005-2006). To prepare it for the Polish project, it underwent significant modifications at Acciona’s technology park in Noblejas, Spain, starting in 2021. Project Manager Andres Aguilar-Gonzalez from Herrenknecht expressed his satisfaction with the rebuild:
"It’s great to see we were able to help Acciona rebuild such a large TBM that had already proven itself in a European project so many years ago."
One of the adjustments immediately apparent concerns the huge cutting wheel. For Madrid, Herrenknecht had developed the combination of an inner cutting wheel with an independently rotating outer cutting wheel operating in the same plane, which made it possible to apply an extremely high torque into the ground if required. This project-specific configuration was not needed for the job in Poland and a one-piece cutting wheel was designed and built instead. In addition, a number of improvments were made, such as replacing the previous system for injecting the annular gap grout with a modern two-component system, installing a quick-unloading system for the segments and assembling the segment ring in semi-automatic mode.
Safety was also a priority, as methane gas was detected during dewatering drilling. The TBM was equipped with additional sensors for gas monitoring, a secondary ventilation system, and ATEX-certified components—making it the first TBM in Poland with such an extensive methane detection system.
Nearly 20 Herrenknecht field service experts contributed to the modifications, with support from Group companies Formwork and TMS, which supplied tunnel lining segment molds and multi-service vehicles, respectively. This project highlights the remarkable potential of reusing and upgrading TBMs, reinforcing the value of sustainability and engineering innovation in large-scale infrastructure development.
