A 21st Century NEC: The Challenge of Civil War Era Tunnels

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This post is the fourth in a series focused on examining the top investment needs of the Northeast Corridor. While earlier posts looked at general needs on the corridor, including priority investments and state of good repair, we are now looking at specific infrastructure investments. Our last post focused on NEC's decaying bridges and the post below takes a look at tunnels.

>>The aging, poorly maintained Baltimore and Potomac Tunnel is one of the largest, most expensive state-of-good-repair projects on the NEC and, as such, is a major barrier to increasing capacity and improving trip times.

As we have outlined before, aging infrastructure is a serious obstacle to achieving high speeds on the NEC, creates major bottlenecks to increasing service, and causes breakdowns that seriously damage reliability.

The Baltimore and Potomac Tunnel

On the NEC, there may be no better example of aging, obsolete infrastructure than the Baltimore and Potomac Tunnel. The B&P Tunnel is a section of the NEC just south of Baltimore Penn Station that carries Amtrak's NEC and MARC's commuter trains beneath the west side of Baltimore. The tunnel is sometimes referred to as the B&P Tunnels (plural) because of two open cut sections that break it into three segments.

At approximately 1.4 miles, the B&P Tunnel is longer than Baltimore's other famous tunnel: the Union Tunnel just east of Baltimore Penn Station, which is about 0.6 miles long. However, the most stunning feature of these tunnels is not their length, it is their age. Completed in 1873, eight years after the end of the American Civil War, they are both almost 140 years old.

The B&P Tunnel's western portal in Baltimore, MD
The B&P Tunnel's western portal in Baltimore, MD

View NEC Civil War Era Tunnels in Baltimore in a larger map


Without question, the B&P Tunnel must be replaced. Already, it requires a level of maintenance that goes well beyond basic infrastructure upkeep. The tunnel's Civil War-era design creates constant maintenance issues. For example, unlike tunnels built today that are made out of reinforced concrete or even other aging tunnels on the NEC that are lined with steel, the B&P Tunnel is constructed of brick masonry. As a result, it is highly susceptible to water infiltration and requires frequent inspection of their structural integrity.

This extra care is with good reason. The tunnel has had several, major structural problems over the years. During the days of the Pennsylvania Railroad, a section of the tunnel near Penn Station collapsed. Instead of repairing the tunnel, engineers solved the problem by digging out the collapsed section and turning it into an open-air "cut." In the 1970s, the tunnel's floor was lowered and its walls were stabilized to correct for other structural problems.


Besides maintenance issues, the B&P Tunnel represents a major constraint on NEC capacity and speed. The tunnel and its approaches force the NEC to narrow from four tracks down to two. Even more problematic is the tunnel's alignment. Because of its S-curve shape, trains traveling northbound must travel at a speed of 30 miles per hour. In fact, the curvature of the tunnel and its approaches results in speeds no greater than 40 mph through most of Baltimore. This is exacerbated by the significant grades that exist in the tunnels, which also limit train speeds. The B&P Tunnel has a mile-long, 1.34 percent grade and the Union Tunnel has a 1.2 percent grade. These may not sound like much, but these grades make for steep climbs for heavy trains.

This bottleneck affects both local train service in Baltimore and intercity rail service up and down the corridor. The tunnel currently supports the operations of both Amtrak and MARC, Maryland's state-run commuter rail service whose Penn Line runs from Baltimore to Washington, DC. Daily traffic in the tunnel is high with 52 MARC trains and 80 Amtrak trains using it, including both Northeast Regional and Acela Express service. The B&P Tunnel also sees significant freight activity with both Norfolk Southern and CSX trains using it.

The two-track design spells trouble for the increase in rail traffic that is planned to occur in and through Baltimore. MARC intends to increase its commuter rail service through the B&P Tunnel from the current 26 daily round trips to 75 in 2030. Amtrak envisions similar service increases in the future as well, growing from 40 daily round trip trains to 55 in 2030.

Plans For Replacement

Due to the severe maintenance and capacity problems of the B&P Tunnel, the NEC Master Plan included the cost of its complete replacement as part of the $14 billion in Phase 1 Priority Improvements. There is no doubt that a new tunnel would be expensive. In a 2009 report, Amtrak estimated that a new, replacement B&P Tunnel would cost about $1.25 billion, an enormous portion of the total $8.8 billion state-of-good-repair backlog on the Amtrak-owned portions of the line.

Planning for the replacement has been underway since at least 2005, when the FRA released a preliminary study (PDF) on the passenger and freight rail network in Baltimore, following a devastating fire in the Howard Street freight tunnels under Baltimore in 2001. Among other findings, the study identified potential alignments for new passenger tunnels to replace the B&P Tunnel (in red):


According to Amtrak, replacing the B&P Tunnel would generate major transportation benefits. The project would transform the experience of riding the NEC to and through Baltimore. According to the NEC Master Plan, Amtrak plans to completely decommission the existing tunnel and construct a new tunnel for passenger rail under West Baltimore. The new tunnel would mitigate the current maintenance problems that plague this section of the NEC and allow Amtrak to reduce travel time through Baltimore. A separate tunnel for freight rail traffic would be constructed to provide a dedicated route through the city, and the original B&P Tunnel would be abandoned.

Already, the State of Maryland and Amtrak are pushing ahead with the tunnel replacement project. In 2009, the Maryland legislature passed a resolution (PDF) in support of new tunnels under Baltimore. Resolutions, of course, do not pay for new tunnels under densely developed cities. That same year Maryland applied for a federal grant, and in January 2010, the state was authorized $60 million in federal stimulus funding to study the impact of potential new tunnel alignments under Baltimore.

Next Steps

The story of the B&P Tunnel is a microcosm of the larger NEC. The plans for replacement are there, but the funding remains the biggest obstacle to achieving progress. Right now, it is difficult to imagine Amtrak or Maryland finding the scale of financial support necessary for replacing the tunnel. After recent debates about reducing the debt, Congressional support for transportation infrastructure projects is languishing and Republicans continue to attack the federal high-speed intercity rail program, which has been supporting the B&P Tunnel replacement effort so far.

Despite the lack of will from Congress, the B&P tunnels must be replaced. While old age can be a virtue in many areas, transportation infrastructure is clearly not one of them. If the tunnels reach 150th birthday with no end in service in sight, we can hold a funeral for the death of America's commitment to infrastructure investment.

Image: FRA. 2005. Report To Congress: Baltimore's Railroad Network, Challenges and Alternatives.


In 20 or 30 years only the results of what we do now will matter: nobody will care about the cost.

when you rebuild the tunnels keep the outside pre war design in place (the stone look) don't kill off the artistic design.

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