American Underground-Construction Association's Featured Project

Each month AUA will feature an outstanding Underground Project currently under construction, featuring its unique aspects in terms of technology, location, function, etc. Contact AUA to nominate projects.

This month's Featured Underground:

Los Angeles Metro Red Line

Santa Monica Mountains Tunnels

Excavation of one of the most difficult segments of the Los Angeles Metro Red Line was recently completed with the holing-through of twin tunnels through the Santa Monica Mountains, linking downtown Los Angeles and the San Fernando Valley. The first tunnel broke through on October 22, 1997 at the La Brea Shaft near Hollywood Boulevard; the second breakthrough occurred early on November 7, 1997. Excavation of these tunnels by the joint venture of Traylor Bros. and Frontier Kemper Constructors, Inc. marks a major milestone in the construction of the North Hollywood Extension of the Metro Red Line.

Excavation was accomplished by two 22' 8" diameter tunnel boring machines (TBMs) named "Thelma" and "Louise" over a one and one-half year time frame. The tunnels are 12,630 feet in length and were created in six distinct geologic formations, ranging in depth from 165 to 900 feet. Unlike previous segments of the Metro Red Line, which were built through loose sedimentary ground, these tunnels pass primarily through solid rock and seismic fault zones under steep mountain terrain. The cost of the project was $154 million.

Approximately 125 men and women worked on the project daily. In the process they excavated more than 312,000 cubic yards of material, and installed more than 10.2 million pounds of steel. More than 91,000 cubic yards of concrete will be poured when the final tunnel liner is completed.

Los Angeles Mayor and MTA Chairman Richard J. Riordan was quoted as saying, "While the MTA's subway program has not been without controversy, one fact remains clear: today's breakthrough is another step toward completing the North Hollywood extension. This milestone serves as a signal to the public and the MTA's funding partners that the agency is committed to meeting the challenges of finishing this and other transportation projects already underway."

The Metro Rail subway is being built in segments. One 6.5 mile section is already in service, transporting approximately 40,000 riders daily between Union Station and Wilshire & Western. The rest of the Metro Red Line system, which will run underground up Vermont to Hollywood Boulevard and then through the Santa Monica Mountains to Universal City and North Hollywood, is under construction. Service to Hollywood is planned for December 1998; service to Universal City and North Hollywood in the year 2000.

In the last 10 years, during construction of the entire Metro Red Line, enough material has been excavated to fill the Pasadena Rose Bowl 3 1/2 times, enough steel to build 90,000 automobiles and enough concrete to build a 5-foot wide sidewalk from Los Angeles to Boston. The $5.4 billion currently expended for all Metro Red Line and light rail Blue and Green line construction has created or maintained 130,000 direct jobs and over 183,000 indirect jobs for a total of more than 313,000 jobs.

MTA's Metro Rail system, comprised of the Red, Blue and Green lines, currently spans 48 miles and serves a daily weekday ridership of nearly 110,000. In the year 2000 total daily ridership will exceed 170,000.

To learn more about Los Angeles Metro Construction go to http://www.mta.net/.

underground tunnel Los Angeles Metro Rail

PAST FEATURES:
The Central Artery/Tunnel Project in Boston, Massachusetts. The Central Artery, a six-lane elevated road built in the 1950s to handle about 75,000 vehicles a day, is now jammed with over 190,000. A few years ago, with the specter of 14-15 hour a day traffic jams looming in our region's future, the Massachusetts Highway Department began construction of the Central Artery/Tunnel Project.