The LA Times is reporting that the California bullet train project may be facing significant budget and schedule issues, largely because of a 13.5-mile tunnel beneath Pacheco Pass east of Gilroy. The article reports that the current budget for the 54-mile segment between Gilroy and Chowchilla is $5.5B, but experts that they interviewed for the story put the cost of the twin-bore tunnel itself at between $5.6 to $14.4B. Geological and geotechnical drilling and testing are currently underway for the tunnel which will be up to 1,000 feet below ground through the challenging Franciscan Complex. Don’t forget about the challenges of a seismically active area and at least one major fault crossing. The designers and engineers for that project are going to have their hands full with that one!
Early indications are that a collapse of a subway tunnel station still under construction was to blame for the sinkhole that destroyed Cologne’s Historical Archive, home to documents dating back to 922 A.D. More info after the break. (Photo by DPA via Spiegel Online)
PITTSBURGH, PA – January 18, 2010 – Nicholson was recently awarded a subcontract by E.E. Cruz and Tully Construction Co., a Joint Venture that includes approximately 200,000 SF of diaphragm walls for the construction of the 96th Street station box as part of New York City’s Second Avenue Subway project. Nicholson’s contract also includes jet grouting for a subgrade strut, water cutoff, and temporary support of excavation; compensation grouting for two buildings at excavations for ancillary structures; micropiles within an existing building; and curtain grouting in rock. The project owner is the Metropolitan Transit Authority. [Editor] Click through for the entire press release from GeoPrac.net sponsor Nicholson Construction. [/Editor] […]
In the mountains of Peru a tunnel-boring machine named â€œPacha Mamaâ€ is grinding through the heart of the Andes under rock as deep as 6,890 ft. It is carving away at a 20.2-kilometer-long tunnel through the South American Continental Divide to deliver water to arid coastal farmland.
This is a really interesting project, known as the Los Olmos project, and a nice little article. Normally for a civil tunnel project you drill geotechnical holes beforehand to know what kind of material you’re dealing with. In this case, because of the depth, they don’t have that luxury, so all decisions will be made on the fly. The depth of the tunnel creates some very challenging rock mechanics and logistics problems as well! (Illustration by Odebrecht)