Proposals under consideration to replace the aged Baltimore and Potomac Tunnel with a new rail tunnel network arcing northwards have been estimated at about $4 billion.Planners have no funding currently secured to carry out the project once the $60 million study phase concludes in 2017. But they say the cost is necessary to replace the 140-year-old tunnel with a rail route that can hold up for a century to come.
“We don’t build tunnels every year,” said Maryland Department of Transportation Project Manger Jacqueline Thorne, on October 6, who spoke at a public outreach session on newly narrowed down B&P Tunnel Project plans. “We want to build it so it lasts at least a hundred years.”
Proposals to rebuild the existing twin-track 1.4-mile B&P tunnel via cut and cover excavation have now been thrown out. A proposal that would have seen a four-track network cutting underneath the existing tunnel has also been nixed.
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That leaves two plans on the table. The first is maintaining and operating the current tunnel, an option that’s still on the books largely so planners have a point of comparison. The second is a network of four single-track tunnels arcing north around the current B&P path. The exact path of the network is still under study, with three different routes being considered.
They would travel distances underground ranging from 1.9 miles to 2.2 miles while averaging a depth of between 130ft and 140ft.
Keeping the current tunnel open for use requires maintenance costing about $4 million per year, Thorne said. Those costs are expected to double over the course of a decade to $8 million annually.