Mayor Antonio Villaraigosa was joined by Supervisor Zev Yaroslavsky and members of the L.A. City Council at the groundbreaking ceremony.
"It's very inexpensive compared to other technologies," said Yaroslavsky. "It will move a lot of people for very little money."
The project is the first to begin construction under the new Measure R transportation sales tax. The extension was set to open in 2015, but the new tax money speeds up the project by three years.
Officials say the Orange Line has exceeded expectations. When it opened they expected about 5,000 to 7,000 riders a day. Right now there are 22,000 riders a day.
"The thousands of people that commute daily on the 405, the thousands of people that commute back and forth from Santa Clarita Valley, from Simi Valley, this project will remove those cars and get them to work at a smooth, expeditious matter," said L.A. City Councilman Dennis Zine.
In Chatsworth, the new Orange Line will connect with Amtrak trains as well as Metrolink trains coming in from Oxnard and Simi Valley. Residents feel it will be an easier way to get around and ease congestion in the West Valley.
"I think you'll find people from the Simi Valley area and over the hill will take that line by the thousands and it makes travel simple," said James Cunningham, a Chatsworth resident.
In addition officials estimate the project will create the equivalent of 3,000 full-time jobs and pump $461 million into the local economy. It's expected to open by the middle of 2012.