[ad_1]
Austin’s billion dollar transit expansion requires the extension of an underground light rail tunnel from Auditorium Shores to Lively Middle School on South Congress Avenue to the south.
The change could cost hundreds of millions of dollars, but transportation planners vow to incorporate it into the budget approved by Austin voters in November when they approved a tax increase of 8.75 cents per $ 100 property value.
“It will certainly be more expensive to build,” said Randy Clarke, CEO of Capital Metro, during a board meeting of the Austin Transit Partnership (ATP) about the expanded tunnel plans. The independent local government company was founded to implement the transit expansion called Project Connect.
Technical challenges from underground utilities, floodplains and traffic are forcing the adjustment, according to ATP officials.
One of two light rail lines included in Project Connect would take passengers from a downtown subway station near Republic Square Park through a tunnel under Lady Bird Lake to an underground station at Auditorium Shores.
From there it gets complicated.
The tunnel under Lady Bird Lake must be deep enough to be in the bedrock. At this depth, according to a presentation to the ATP board, it is “impossible” to come across the earth directly south of the lake.
The next point at which the tunnel could emerge is not possible due to several important intersections and the 100-year-old flood area on Riverside Drive, say the planners. To the south of this, the flood plain of Bouldin Creek disrupts a possible “tunnel portal” at which the Orange Line could arise.
Austin Transit Partnership
A slide from a presentation this week to the Austin Transit Partnership Board explains the technical challenges involved in creating an underground tunnel near Lady Bird Lake.
As the tunnel continues south, South Congress Avenue begins ascending, creating a new “hunting grade” engineering challenge. So the first opportunity for the Orange Line to get to the surface would be on South Congress Avenue near Academy Drive, officials said.
An alternative plan would be to have the light rail tunnel underground more than half a mile below South Congress Avenue and “daylight” – in transit parlance – near Lively Middle School on Leland Street.
The longer tunnel would allow more flexibility in redesigning streets and sidewalks to accommodate the light rail infrastructure, said Peter Mullan, director of architecture and urban development at ATP. The shorter tunnel would cost less, but would create additional technical constraints, he said. The longer tunnel would mean the SoCo station would be underground instead of on the surface.
Austin Transit Partnership
A slide from the presentation shows two ways the Orange Line might exit the subway on South Congress Avenue.
Some board members warned transportation planners not to make too many changes to Project Connect without first thinking about how to pay for them.
“Every time we go underground, you all know the cost goes up exponentially,” said ATP board member Tony Elkins, a transportation finance expert at investment firm BBGI Global Infrastructure.
“Tunnels can cost $ 700 to $ 1 billion per mile,” said Elkins. “There are higher operating and maintenance costs in tunnels.”
It’s too early in the planning process to set a price for the two expanded tunnel options, but cost estimates should be clearer by September, Clarke said. He added that an elongated tunnel can provide benefits such as reduced travel times and improved safety by removing the light rail from the street and avoiding pedestrians and vehicles in an already busy shopping area.
ATP officials said they would work within the voter-approved budget and seek additional funding through federal grants or other sources, “not from local taxpayers just to be clear,” Mullan said.
Starting next week, the public will have the opportunity to attend a variety of community meetings on both light rail lines. The lonely in-person open house, scheduled for July 31 at the Austin Central Library, has been canceled due to concerns about rising COVID-19 cases.
[ad_2]
