AUSTIN (KXAN) — New preliminary designs for Project Connect’s orange rail line details an underground tunnel at Auditorium Shores, with the track now planned to run beneath Lady Bird Lake. Officials detailed the updated plans, highlighting utility and traffic conflicts with the original proposal of a bridge running over the lake.

Austin voters approved the $7.1 billion Project Connect plan in the November 2020 election. The initiative details a massive expansion to the city’s public transit options.

The orange line project encompasses a 20-mile light rail corridor running along Lamar Boulevard and Congress Avenue. Corridor parameters extend from the Tech Ridge Park & Ride at Howard Lane in north Austin, down south to Slaughter Lane.

Peter Mullan serves as chief of architecture and urban design for Austin Transit Partnership. He noted two potential tunnel options for an underground station at Auditorium Shores, adding the geological landscape is ideal for tunnel. Officials said plans involving an above-ground bridge were scrapped due to the following concerns:

• Vertical ascent from underground to a bridge lacked feasibility
• Substantial utility conflicts (water, wastewater, storm sewer, electrical vaults) near surface between Lady Bird Lake and 3rd Street
• Federal Emergency Management Agency flood zone risks near Auditorium Shores, impacting the orange line tunnel portal

The first tunnel option would resurge above ground south of Nellie Street and Academy Drive and would come above ground as it enters the downtown retail district. Mullan said an above ground station would be near Lively Middle School, given this area is the first flat spot the line gets to, which is necessary for subway stations.

The second tunnel option includes a longer stay underground with a reemergence just south of Leland Street. He said this option would allow for an underground station in the middle of the South Congress retail district, allowing a bit more flexibility on station entrances and access points.

Key criteria ATP is still weighing includes Americans with Disabilities Act compliance and accessibility, pedestrian and cycling impacts, traffic effects and the construction costs of each tunnel option.

Mullan said both tunnel options add costs to that portion of the project costs, but ATP built in a degree of financial flexibility for slight project changes. He added the project is still in preliminary stages, with initial cost estimate updates expected in the coming months.