A key regional transportation committee on Wednesday approved $12.5 million for Sonoma-Marin Area Rail Transit to rebuild the line as far north as Airport Boulevard and possibly add a new station there.

The funds were approved by the Metropolitan Transportation Commission's programming and allocations committee.

On Jan. 23, the committee's action will go to the full MTC board, which usually follows those recommendations.

"The upgraded track increases our operations for north Santa Rosa and gets the trains back and forth to the operations and maintenance facility in a timely manner," said SMART Director Debora Fudge, a Windsor councilwoman. "It also gets us closer to the workers at the airport and halfway to Windsor."

The MTC committee allocated $750,000 to design the project and $11.7 million for construction of the track and station. The money comes from Bay Area toll bridge revenue.

It still leaves SMART $2.5 million short of the estimated cost, according to MTC program manager Shruti Hari.

MTC is requiring that SMART make it a priority to use revenue from the quarter-cent sales tax and any savings from the ongoing construction to make up the difference.

SMART is now rebuilding track, building stations and buying rail cars, at a cost of about $360 million, to start service between Guerneville Road in Santa Rosa and downtown San Rafael in late 2015 or early 2016.

The additional funds approved Wednesday will allow SMART to rebuild the line from Guerneville Road to Airport Boulevard, where SMART is planning a $20 million operations and maintenance facility.

The track work could be completed by the time service is scheduled to start, said Farhad Mansourian, SMART general manager.

If the tracks are not rebuilt to passenger train standards, which allows speeds of 79 mph, SMART would be running trains to the maintenance facility over the existing freight line at 25 mph.

The SMART board has not approved a train station at Airport Boulevard, but the additional funds raise that possibility.

An Airport Boulevard station could serve the Charles M. Schultz-Sonoma County Airport and 6,000 workers in business parks near the airport.

"It also shows support from MTC for SMART in a direct way. It provides funding in the North Bay for transit that we normally don't see," Fudge said.