MTA responds to TRAC on Red Line tunnels
Nate Payer, a spokesman for the Transit Riders Action Council of Metropolitan Baltimore, raised questions about the Maryland Transit Administration's plans to tunnel under certain neighborhoods along the proposed Red Line Route, suggesting that the construction could damage historic structures on the surface.
Here, at Getting There's request, is the MTA's response from Henry Kay, executive director for transit development and delivery:
Based on the limited amount of design we have done, the top of the Red Line tunnels proposed through the Downtown area will be approximately 40 to 50 feet below the street surface. The bottom of the tunnel is another 20 feet down, or approximately 60 to 70 feet below the surface. The depth of the tunnels is determined by the need to avoid impacts to existing structures and foundations. Ground conditions vary greatly along the three-mile downtown tunnel, but we expect a mixture of rock and soft ground with a high water table. Tunneling technology has significantly advanced since the Metro Subway construction which will further reducing construction-related impacts. Noise and vibration from operation of the Red Line will be mitigated through the design of the track inside the tunnel. As the tunnel design work gets underway we will be looking for ways to further minimize the possibility of surface impacts such as depth and alignment changes.
Portions of the existing Metro Subway tunnel through Downtown are at a similar depth to the Red Line and were successfully constructed through comparable soil conditions under buildings of similar construction. Another nearby example of tunneling under similar conditions is in Washington where portions of the Metrorail tunnels were constructed in very similar depth and subsurface conditions. The deep sections between State Center and Mondawmin were due to the need to avoid the existing CSX and Amtrak tunnels and accommodate the rapid rise in ground elevation as you move to the northwest rather than any concerns about impacts to structures.
In response to a question from Getting There, MTA spokesman Terry Owens clarified that Kay's reference to a downtown tunnel in fact encompasses the entire 3-mile segment including parts under Fells Point and Canton.
TRAC's concerns are noted, but it is unclear that the group has the engineering expertise to make its case. It isn't enough to show the Red Line faces engineering problems -- all projects of its scope do. TRAC needs to show there are problems no amount of engineering can't solve. And engineers tend to be pretty good problem-solvers.
Of course, the MTA had better show that any solutions it devises to engineering challenges pass muster with qualified outside experts. Residents of the neighborhoods in its path deserve that assurance before the first scoop of dirt is shoveled.
