Supporters of a more expensive, all underground subway path for the so called “D-2” downtown light rail transit expansion passed out hundreds of T-shirts in advance of Tuesday night’s DART board meeting.

They are campaigning to change courses from the mostly surface route currently favored by the transit agency.

D-2 would relieve traffic on the single existing light rail route which carries all transit trains through downtown Dallas now.

Subway support has grown through opposition to the proposed surface routes, according to Matt Tranchin, Executive Director of the Coalition for a New Dallas.

“What’s changed in the past year is those stakeholders have come together and realized any surface line is bad for the heart of Dallas,” Tranchin said.

DART says the cost could be twice as high for an all underground route.

At the same time, supporters of another new DART rail line fear a downtown subway would come at their expense.

The Cotton Belt line would link Plano with D/FW Airport. Last month, the Plano City Council agreed to pay an extra $12 million to speed completion of a Cotton Belt rail transit line.

The Cotton Belt route also crosses Carrollton.

“I think we need some sort of transit on the Cotton Belt line. I think that’s imperative,” Carrollton Mayor Matthew Marchant said.

But the Carrollton mayor said Bus Rapid Transit technology instead of light rail could cut the cost of the Cotton Belt by two-thirds. BRT uses rubber wheel buses on dedicated busway lanes removed from regular street traffic. It has been used in Los Angeles other U.S. cities.

“It is a much more affordable form of transit that in my opinion would allow both things to happen. I think you could have the Cotton Belt be developed as a BRT and also free up enough money for D-2 in Downtown to be a subway,” Marchant said.

Carrollton Mayor Marchant also serves on the North Texas Regional Transportation Council. He supports completion of the D-2 project as well as the Cotton Belt line.

“A strong downtown Dallas is really important for inner ring suburbs like Carrollton and I think for the entire region,” Marchant said. “If you choose BRT on the Cotton Belt, I don’t think there is a rivalry.”

The subway supporters hope to change DART plans before final decisions are made in the next few months.

“Right now D-2 is a need for the entire system and it think it’s a need for those of us who live work and play in the city of Dallas to have an alignment that doesn’t hinder future growth,” Tranchin said.

DART is also pursuing a downtown street car project to link the Oak Cliff line that currently ends at Houston Street with the Uptown McKinney Avenue Trolley.