In 2009, studies began for a replacement of the Baltimore and Potomac (B&P) Tunnel. This tunnel, located immediately west of Baltimore Penn Station, has sharp curves, limiting passenger trains to about 50 km/h today. The plan was a two-track passenger rail tunnel, called the Great Circle Tunnel since it would sweep a wide circular arc; see yellow line here. It would be about 3 kilometers and cost $750 million, on the high side for a tunnel with no stations, but nothing to get too outraged about. Since then, costs have mounted. In 2014, the plan, still for two tracks, was up to $1 billion to $1.5 billion. Since then, costs have exploded, and the new Final Environmental Impact Statement puts the project at $4 billion. This is worth getting outraged about; at this cost, even at half this cost, the tunnel should not be built. However, unlike in some other cases of high construction costs that I have criticized, here the problem is not high unit costs, but pure scope creep. The new scope should be deleted in order to reduce costs; as I will explain, the required capacity is well within the capability of two tracks.
First, some background, summarized from the original report from 2009, which I can no longer find: Baltimore was a bottleneck of US rail transportation in the mid-19th century. In the Civil War, there was no route through the city; Union troops had to lug supplies across the city, fighting off mobs of Confederate sympathizers. This in turn is because Baltimore’s terrain is quite hilly, with no coastal plain to speak of: the only flat land on which a railroad could be easily built was already developed and urbanized by the time the railroad was invented. It took until the 1870s to build routes across the city, by which time the US already had a transcontinental railroad. Moreover, intense competition between the Pennsylvania Railroad (PRR) and the Baltimore and Ohio (B&O) ensured that each company would built its own tunnel. The two-track B&P is the PRR tunnel; there’s also a single-track freight tunnel, originally built by the B&O, now owned by CSX, into which the B&O later merged.
Because of the duplication of routes and the difficult geography, the tunnels were not built to high standards. The ruling grade on the B&P is higher than freight railroads would like, 1.34% uphill departing the station, the steepest on the Northeast Corridor (NEC) south of Philadelphia. This grade also reduces initial acceleration for passenger trains. The tunnel also has multiple sharp curves, with the curve at the western portal limiting trains today to 30 mph (about 50 km/h). The CSX tunnel, called Howard Street Tunnel, has a grade as well. The B&P maintenance costs are high due to poor construction, but a shutdown for repairs is not possible as it is a key NEC link with no possible reroute.
In 2009, the FRA’s plan was to bypass the B&P Tunnel with a two-track passenger rail tunnel, the Great Circle Tunnel. The tunnel would be a little longer than the B&P, but permit much higher speeds, around 160 km/h, saving Acela trains around 1.5 minutes. Actually the impact would be even higher, since near-terminal speed limits are a worse constraint for trains with higher initial acceleration; for high-performance trains, the saving is about 2-2.5 minutes. No accommodation was made for freight in the original plan: CSX indicated lack of interest in a joint passenger and freight rail tunnel. Besides, the NEC’s loading gauge is incompatible with double-stacked freight; accommodating such trains would require many small infrastructure upgrades, raising bridges, in addition to building a new tunnel.
In contrast, the new plan accommodates freight. Thus, the plan is for four tracks, all built to support double-stacked freight. This is despite the fact that there is no service plan that requires such capacity. Nor can the rest of the NEC support double-stacked freight easily. Of note, Amtrak only plans on using this tunnel under scenarios of what it considers low or intermediate investment into high-speed rail. Under the high-investment scenario, the so-called Alternative 3 of NEC Future, the plan is to build a two-track tunnel under Downtown Baltimore, dedicated to high-speed trains. Thus, the ultimate plan is really for six tracks.
Moreover, as pointed out by Elizabeth Alexis of CARRD, a Californian advocacy group that has criticized California’s own high-speed rail cost overruns, the new tunnel is planned to accommodate diesel trains. This is because since 2009, the commuter rail line connecting Baltimore and Washington on the NEC, called the MARC Penn Line, has deelectrified. The route is entirely electrified, and MARC used to run electric trains on it. However, in the last few years MARC deelectrified. There are conflicting rumors as to why: MARC used the pool of Amtrak electric locomotives, and Amtrak is stopping maintaining them as it is getting new locomotives; Amtrak is overcharging MARC on electricity; MARC wants fleet compatibility with its two other lines, which are unelectrified (although the Penn Line has more ridership than both other lines combined). No matter what, MARC should immediately reverse course and buy new electric trains to use on the Penn Line.
Freight trains are more complicated – all US freight trains are dieselized, even under catenary, because of a combination of unelectrified yards and Amtrak’s overcharging on electric rates. However, if freight through the Great Circle Tunnel is desired, Amtrak should work with Norfolk Southern on setting up an electric district, or else Norfolk Southern should negotiate trackage rights on CSX’s existing tunnel. If more freight capacity is desired, private companies NS and CSX can spend their own money on freight tunnels.
In contrast, a realistic scenario would ignore freight entirely, and put intercity and regional trains in the same two-track tunnel. The maximum capacity of a two-track high-speed rail line is 12 trains per hour. Near Baltimore Penn the line would not be high-speed, so capacity is defined by the limit of a normal line, which is about 24 tph. If there is a service plan under which the MARC Penn Line could get more than 12 tph at the peak, I have not seen it. The plans I have seen call for 4 peak tph and 2 off-peak tph. There is a throwaway line about “transit-like” service on page 17, but it’s not clear what is meant in terms of frequency.
Regardless of what the state of Maryland thinks MARC could support, 12 peak regional tph through Baltimore is not a reasonable assumption in any scenario in which cars remain legal. The tunnels are not planned to have any stations, so the only city station west of Baltimore Penn is West Baltimore. Baltimore is not a very dense city, nor is West Baltimore, most famous for being the location of The Wire, a hot location for transit-oriented development. Most of Baltimore’s suburbs on the Penn Line are very low-density. In any scenario in which high-speed rail actually fills 12 tph, many would be long-range commuters, which means people who live in Baltimore and work in Washington would be commuting on high-speed trains and not on regional trains. About the upper limit of what I can see for the Penn Line in a realistic scenario is 6 tph peak, 3-4 tph off-peak.
Moreover, there is no real need to separate high-speed and regional trains for reasons of speed. High-speed trains take time to accelerate from a stop at Baltimore: by the portal, even high-acceleration sets could not go much faster than 200 km/h. An in-tunnel speed limit in the 160-180 km/h area only slows down high-speed trains by a few seconds. Nor does it lead to any noticeable speed difference with electrified regional trains, which would reduce capacity: modern regional trains like the FLIRT accelerate to 160 km/h as fast as the fastest-accelerating high-speed train, the N700-I, both having an acceleration penalty of about 25 seconds.
The upshot is that there is no need for any of the new scope added since 2009. There is no need for four tracks; two will suffice. There is no need to design for double-stacked freight; the rest of the line only accommodates single-stacked freight, and the NEC has little freight traffic anyway. Under no circumstances should diesel passenger trains be allowed under the catenary, not when the Penn Line is entirely electrified.
The new tunnel has no reason to cost $4 billion. Slashing the number of tunnels from four to two should halve the cost, and reducing the tunnels’ size and ventilation needs should substantially reduce cost as well. With the potential time gained by intercity and regional trains and the reduced maintenance cost, the original budget of $750 million is acceptable, and even slightly higher costs can be justified. However, again because the existing two-track capacity can accommodate any passenger rail volume that can be reasonably expected, the new tunnel is not a must-have. $4 billion is too high a cost, and good transit activists should reject the current plan.