California rail agency begins geotechnical work for underground tunnels

The California High-Speed Rail Authority (CHSRA) and its contractor Kleinfelder have begun performing geotechnical work for underground high-speed rail tunnels in the Pacheco Pass.

Drilling crews are taking soil and rock samples from several locations within the public right of way along State Route 152. These samples will be used to determine the exact conditions of the ground below, where roughly 13 miles of future high-speed rail tunnels are proposed.

The tunnels are part of the project's San Jose-to-Merced section. Although the process to environmentally clear that segment is still underway, it's "crucial" to get a head start on geotechnical investigations, CHSRA officials said in a press release.

"If this goes out to bid, we will have data available for the bidders ... so they can evaluate the conditions that the tunnel would be going through," said CHSRA Engineering Manager Randy Anderson in a video about the geotechnical work.

Once the core ground samples are logged, they're moved to a storage facility in Gilroy, California. Researchers then collect more data and send samples to testing labs to obtain engineering properties of the rock formations, according to the agency.