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Metro Says Fully Underground Connector Feasible, Could Cost 20% More

By Eric Richardson
Published: Thursday, November 19, 2009, at 03:54PM
Regional Connector - Underground Map Metro

A rendering released today by Metro shows the routing that a fully underground Regional Connector might take.

Little Tokyo's call for a fully grade-separated Regional Connector has been answered. Metro today used its blog to unveil early engineering study results, which it then presented to a Little Tokyo working group meeting later in the evening.

The transit agency warned that the new configuration, which continues under 1st and Alameda below-ground, could add $200 million to the project's cost. That didn't faze community members, who voted to endorse further study of the new option.

The new option presents a significant change for the Regional Connector project, proposed to connect all of Metro's light rail lines and allow trains to run from Long Beach to Pasadena and Culver City to East L.A. At public meetings in late 2007 and early 2008, Metro staff was clear that the design of the Gold Line Eastside Extension precluded an option that would both be fully underground and have a Little Tokyo station.

While Metro has been studying what it calls an "underground-emphasis" option for the Connector, designs have shown the line surfacing on the block currently occupied by Office Depot and crossing 1st and Alameda at street level. That would allow it to connect into the existing at-grade station.

The new alternative would instead place a station underneath the Office Depot site, with trains continuing under the intersection as tracks split to emerge via portals along Alameda and in the middle of 1st.

The Alameda portal would be located north of Temple street, while the 1st street tracks would rise just east of Alameda, leveling off just past Hewitt. Some temporary track on 1st would allow the newly-opened Gold Line Eastside Extension to continue operating throughout construction.

The fate of the existing Little Tokyo / Arts District station would be uncertain. The underground tracks would enable trains to run from Downtown to Pasadena or East L.A., but direct service from Pasadena to East L.A. could only continue if Metro kept the above-ground station and tracks.

While the underground alignment was welcomed, construction impacts could still prove tricky. Both the underground station and the 1st and Alameda crossing would be built using cut-and-cover construction. That requires closure of the intersection as crews dig down far enough to erect a cap over the site and continue the work below.

Metro also needs a site to lower the twin tunnel boring machines into the ground. That's a 3-4 week process for machines that are 26-feet in diameter and 300 feet long. Likely sites are 2nd and Central or 2nd and Hope.

Along with making Little Tokyo stakeholders happy, the new alternative has benefits for those involved in Broadway revitalization. While stations at 5th and Flower and 2nd and Hope have been pretty firmly set, the third Connector station was to go either at 2nd and Broadway or 2nd and Los Angeles. With the fourth underground station, Metro would choose the Broadway siting.

Metro staff will now add the fully underground option as a third build alternative in the environmental process. Cost estimates currently range from $709 million for the above ground alternative to approximately $1.1 billion for the new option.

It will not be until the summer of 2010 that the Metro board chooses one option as the Locally Preferred Alternative.

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Regional Connector

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