Metro de Santiago to use new construction method for line No. 7

A tunnel boring machine (TBM) will be deployed in March to advance construction of Santiago’s US$2.5bn metro line No. 7, while archeological surveys that have taken longer than planned are also expected to wrap up.

The TBM will dig a 6.6km section of the 26km line and be operated by China Railway 16th Bureau Group, which won the construction contract.

A TBM will be used for metro projects for the first time. Previous lines were solely built with the New Austrian Tunneling Method (NATM), Metro de Santiago’s projects chief Osvaldo Cortés told a webinar organized by public-private tunnel and subterranean spaces organization CTES.

The rest of line No. 7 will also be built with the NATM method.

While Cortés didn’t rule out using a TBM for future projects, he added that the method couldn’t be used in certain areas due to soil humidity.

Cortés said all civil works contracts have been awarded, but archeology surveys, which are a key step required for terrain availability, have taken longer than expected and will only be completed by mid-2023.

“We will likely have to mitigate that [delay] during construction,” he said. 

Line No. 7 will serve 19 stations and link the districts of Renca, Cerro Navia, Quinta Normal, Santiago downtown, Providencia, Las Condes and Vitacura.

Operations are expected to begin in 2027, benefiting over 1.3mn users.