Capital Metro unveils initial plans for six underground rail stations in downtown Austin

“A lot of it has to do with the grading,” Mullan said. “It's just very hard to find a place to come out of the ground because you start sloping up, so much so quickly.”

He added that traffic conflicts on the north side of Lady Bird Lake and flood zone issues on the south side of the lake factored into the decision.

Capital Metro is still assessing whether that tunnel would go back to the surface before or after the SoCo Station, located near the intersection of South Congress Avenue and West Johanna Street.

The Government Center/Capitol West Station will be the last underground stop on the north side of the Orange Line. That station will be on Guadalupe Street at either West 12th, 13th or 15th Street.

Capital Metro is also evaluating whether the train will emerge from the tunnel at the intersection of Guadalupe Street and either West 18th Street or just north of West Martin Luther King Jr. Boulevard. The tunnel will not extend onto The University of Texas at Austin campus in large part due to cost constraints, ATP Deputy Program Officer John Rhone said.

The Republic Square Station, which will have stops for the Blue Line and Orange Line, also needed modifications. Because the Texas State Legislature did not pass House Bill 3893, Capital Metro officials said they will not be able to build a tunnel below Republic Square. Instead, the platforms will be located just north of Republic Square on Guadalupe Street. The proposed signature entrance for that station is now at West Fourth and Guadalupe streets.

In addition to the tunneled rail network, Capital Metro plans to make the section of Fourth from the Brush Square to Republic Square a more pedestrian friendly street, giving Austin a “green spine” that cuts through downtown, Mullan said.

The section—named the Downtown Transit Hub—will have three levels. One will be at street level, a second will be a concourse area below ground and the third will be the rail two levels below ground. As with all stations, the hub will be accessible for people of all abilities, using clear signage, elevators and escalators, officials said.