Sonoma-Marin Area Rail Transit agency (SMART) will be able to use a $2.5 million grant it won four years ago after federal assistance allowed the agency to hold onto the funds.

The money will be used for engineering design in preparation for construction of the Larkspur extension, which will connect the Sonoma-Marin rail system to the ferry terminal in Marin County.

The Sonoma-Marin Area Rail Transit agency secured a funding promise from the U.S. Department of Transportation in 2010, but in 2012 was told the grant would lapse unless it could be used by the end of the fiscal year.

For the funds to be used, SMART had to be accepted into the Federal Transit Administration’s New Starts/Small Starts program. With assistance from Rep. Mike Thompson, D-St. Helena, and former Rep. Lynn Woolsey, D-Petaluma, SMART was accepted into the program in September 2013.

The agency has since completed preliminary work that enables it to use the money, according to an announcement from Thompson’s office.

Last month, SMART cleared an even larger funding hurdle, securing $20 million in regional transportation funds for the 2.2-mile Larkspur extension, half the money needed to extend rail service to the ferry terminal.

Another $20 million needed for the extension could come from a federal transportation grant that will be decided on later this year.

SMART is currently constructing a 43-mile rail project between San Rafael and Airport Boulevard north of Santa Rosa, with service anticipated to begin in late 2016.

©2014 The Press Democrat (Santa Rosa, Calif.)