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.
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.