Baltimore and Potomac Tunnel

West portal of B&P Tunnel in 1977.

The Baltimore and Potomac Tunnel (or B&P Tunnel) is a double track, masonry arch railroad tunnel on the Northeast Corridor in Baltimore, Maryland, immediately to the south of Pennsylvania Station. Approximately 140 Amtrak and MARC passenger trains, as well as two freight trains, use the tunnel daily.^[1]

The 7,669-foot (2,338 m) tunnel facility, which passes under the Baltimore neighborhoods of Bolton Hill, Madison Park, and Upton, consists of a series of three tunnel sections—Gilmor Street Tunnel, Wilson Street Tunnel, and John Street Tunnel—delineated by two open air cuts—Pennsylvania Avenue Opening and John Street Opening.^[1][2][3]

History and operations

Constructed by the Baltimore and Potomac Railroad under Winchester Street and Wilson Street in Baltimore, the tunnel opened on June 29, 1873.^[4] The B&P tunnel allowed the Pennsylvania Railroad (PRR) direct access to Washington, D.C. for the first time by connecting its Northern Central Railway affiliate (which arrived in Baltimore from the north) to the Baltimore and Potomac's new spur, which ran to Washington.^[5]

Between 1916 and 1917, the PRR lowered the floor of the tunnel approximately 2 ¹⁄₂ feet to accommodate larger trains. The work included the underpinning of the side walls, installation of a concrete invert slab, and reconstruction of the track structure. The bases of the tunnel walls were chipped away to improve horizontal clearance.^[6]

Prior to the electrification of the PRR's New York City to Washington main line in 1935, the poorly-ventilated tunnel easily filled with smoke from the steam locomotives then in use. The smoke also was a nuisance to the residential neighborhoods above the tunnel.^[6]

The tunnel was lined with gunite to waterproof the arch and prevent icicles from shorting out the catenary wires prior to the initiation of electrified operation. However, financial considerations prevented the PRR from constructing a new passenger tunnel on the Presstman Street alignment, for which it previously had acquired rights. The PRR’s plan had envisioned using the new Presstman Street tunnel and the original bores of the Union Tunnel for passenger operations, while the old B&P Tunnel and the newer bores of the Union Tunnel (completed in the 1930s) would have been used for freight operations.^[6]

In the late 1950s, the tunnel became a hindrance to the growth of PRR’s Trailer-on-Train service, which required additional vertical and horizontal clearance to accommodate semi-trailers on top of railroad flatcars. The curve at Pennsylvania Avenue was the biggest constraint. The PRR modified the tunnel walls and ceiling for a distance of 2,200 feet (670 m) to improve clearance and enable high cars and piggyback trailers to traverse the tunnel without damaging their roofs.^[6] Additionally, a 928-foot (283 m) long gauntlet track was installed on southbound track 3 to route trains 17 inches (430 mm) closer to the middle of the tunnel. However, trains could not operate on track 2 while track 3 and the gauntlet were being used. The gauntlet track effectively created a single-track tunnel when in use; if a freight train broke down while using the gauntlet, the tunnel was closed to traffic until the train was moved.^[6]

Even with the gauntlet, cars with a loading gauge in excess of Plate C or in excess of 16 feet 3 inches (4.95 m) high were prevented from using the tunnel.^[6]

The tunnel underwent rehabilitation as part of the Northeast Corridor Improvement Project in the early 1980s. The repairs included replacing the existing invert, repairing the tunnel lining, upgrading the track structure, installing a new gauntlet track, and rehabilitating the tunnel drainage system. No fundamental change, however, was made in the tunnel’s difficult geometry. Eventually, the gauntlet track was removed due to changes in freight traffic patterns.^[6]

Problems and plans for improvements

The tunnel is a bottleneck for rail traffic along the Northeast Corridor and maintaining it is costly:

• A sharp curve at the south portal of the tunnel prevents southbound trains from exceeding 30 mph (48 km/h) while in the tunnel^[6]
• The spacing between tracks is tight
• There are water infiltration and drainage issues
• An uphill, mile-long, 1.34 percent grade—the steepest grade on the NEC between Philadelphia and Washington—further constrains train performance.^[6][7]

Collectively, the tunnel's height, speed, and capacity limitations threaten the ability for the Port of Baltimore to be competitive with increased shipping volumes.

In June 2008, the U.S. House of Representatives voted to support a study of the environmental impacts of different possible replacement tunnels.^[1] On January 28, 2010, $60 million in funding was awarded under the American Recovery and Reinvestment Act to conduct the study, but not the money that will be required for a replacement tunnel.^[8] Estimates in 2013 put the cost around $1.5 billion.^[9]

B&P Tunnel Project

An outgrowth of the ARRA funds, the B&P Tunnel Project is an environmental and engineering study by the FRA, MDOT, and Amtrak to evaluate potential improvements to the tunnel. Two open houses, in June and October 2014, have been held to share information from the study and to solicit public input.

In October 2014, the study published a Draft Alternatives Preliminary Screening Report, which recommended that four alternatives for the future of the tunnel be carried forward:^[10][11]

• No build (do nothing)
• Rebuild/rehabilitate the existing tunnel, either eliminating the need for a new tunnel or complementing a new tunnel^[3]
• Great Circle Passenger Tunnel: a new 10,900 feet (3,300 m) tunnel on a wide, continuous arc well to the north of the existing tunnel, bypassing it entirely^[12]
• Robert Street South: a new 9,500 feet (2,900 m) tunnel roughly parallel to and within 2–4 blocks of the existing tunnel^[13]

Among the criteria used to evaluate the alternatives was the ability to accommodate double-stack container cars.^[14]

The study also recommended that 11 other alternatives be eliminated, including alignments that varied greatly from the existing alignment and bypassed Pennsylvania Station entirely, those that reused one or more of the three existing tunnel sections, and one that would have utilized the former I-170 "Highway to Nowhere" right of way.^[11]

See also

• Pennsylvania Station (Baltimore)
• Union Tunnel (Baltimore)

References

External links

• U.S. Federal Railroad Administration. Report To Congress: Baltimore's Railroad Network, Challenges and Alternatives. November 2005.
  • Executive Summary
  • "Part 1: Challenges." Discussing the history and recent state of Baltimore rail infrastructure.
  • "Part 2: Alternatives." Discussing possible replacement tunnel alignments along Presstman Street (see page 7-7) or US Route 40, among others (see page 7-9).
• B&P Tunnel Project

Coordinates: 39°18′11″N 76°38′07″W / 39.303°N 76.6352°W / 39.303; -76.6352