Commonwealth Avenue Subway with Boston University Connections

Ah, the B-Line. It is widely celebrated as the most fitness-oriented branch of the Green Line because it encourages people to walk to their destinations, since they will arrive faster than they would by riding it. While the MBTA's health-consciousness is laudable, should their rapid transit options have any responsibility to move people rapidly?

Boston University is the 10th annual winner of the Jack Frost Award for their groundbreaking work in giving as many students frostbite as possible. Their innovative system of unconnected classroom buildings requires frequent crossings of Commonwealth Avenue, maximizing time outside during the winter and allowing them to beat out schools like MIT and Northeastern, where many buildings have heated connections.

As a BU student and frequent Green Line rider, I hold the highly controversial opinion that both of these features are frustrating to deal with. The B-Line is a disappointing mess compared to the light rail lines of similarly-sized cities like Amsterdam. Of course, there are some feasible improvements to the Green Line that could be made quickly and cheaply, like giving trains signal priority and eliminating stations. This proposal is not one of them.

The Idea

The B-Line has way too many street crossings, and BU has way too many unconnected buildings. Commonwealth Avenue would be much more pleasant to travel through with an MIT-style system of underground passages, combined with modern cut-and-cover subway stations spaced half-miles apart. This would have several benefits, including:

1. Much faster Green Line service
2. Fewer car collisions, since fewer students would need to cross Commonwealth Avenue
3. Shorter commutes between classes
4. Less traffic from students crossing the road
5. More room on the Commonwealth Avenue median for separated bike lanes or parks

Since Commonwealth Avenue is very long, I have chosen only to illustrate the straight section between Kenmore Square and Packard's Corner. The section between Kenmore Square and I-90 would look like this:

In BU's East Campus, a new underground station would connect indoors with Warren Towers and the College of Arts and Sciences (CAS), in addition to street entrances. The new BU East station would feature a long mezzanine stretching the length of the platform, with fare control only around staircases. This would allow free, unpaid movement from one end of the station to the other. BU would also need to construct many new underground or elevated passages between the buildings. 

The most important and easiest of these passages to construct would be the connection between the CAS, Marsh Chapel, the School of Theology, the School of Law, and the Mugar Library - GSU complex. This could be achieved by covering over the existing walkway between Mugar, Law, and Theology with a sealed glass and metal enclosure, allowing sunlight in while making it possible to heat the interior. Between this passage, Marsh Chapel, and CAS, new glass windows would be added to the existing cloister, and a passage through the chapel entrance would be opened for general use. Even though nothing else in this proposal is intended to be practical, I would like to see this one connection happen.

The section between I-90 and Packard's Corner would need a similar tunnel network to East Campus. Like the new BU East, a new BU West station would feature a long, unbroken mezzanine to allow free movement between the ends of the underground space. The station at Packard's Corner (officially named "Packards Corner" by the MBTA) would have the same design, though with no BU buildings to connect to. Though I did not include it in this map, an indoor connection with Super 88 might be nice.

The subway tunnel could continue along Commonwealth Avenue under the current B-Line all the way to Boston College, or even reconnect with the D-Line at Reservoir. Along the way, stations would be spaced at roughly 1/2 mile intervals, to ensure that the trains have an opportunity to get up to speed. These stations would be built similarly to Packards Corner, with long mezzanines and occasional indoor connections. The exception would be Boston College, which could connect with a tunnel network at the eponymous school. I am not familiar with that campus, so I will not attempt to design one like I did with BU.

Why is it Implausible?

The B-Line is already popular, and any subway construction under it would require severe disruptions of service. Unfortunately, for these underground passages to be useful, they probably need to be shallow, which necessitates cut-and-cover tunneling—otherwise the time and energy spent to climb down and back up would make them too inconvenient to replace crossing the street. Of course, cut-and-cover also requires ripping up enough of the B-Line to make any service impossible until a roof is built. At that point, it may be more efficient to just use shuttle buses for the duration of construction, meaning that there would be no trolley service on the B-Line for several years. Needless to say, riders would not be happy.

Additionally, building passages that cross streets requires cutting off access to those streets for some time. For some of these streets, like Cummington Mall, there is already very little traffic, so there would be little disruption. For Commonwealth Avenue, however, tunnel or bridge construction would probably have to be staged, so as not to completely block traffic all at once. Even blocking one lane at a time, such construction would cause more congestion on a road which already sees a lot of traffic, and staging would prolong the process.

Lastly, it seems unlikely to me that Boston University would have any interest in a tunnel project like this. I have never heard of a school retrofitting tunnels to connect their buildings—MIT and Northeastern were built with theirs. Such a system is not as flashy or easy to show off as a new skyscraper for the CS department, and despite its utility to existing students and professors, it may not be valuable as a way to attract new students. Given the expense to build tunnels and bridges like these without any direct monetary gains, it may not seem worth it to the administrators.

The next time I walk to school past stuck trolleys and the frozen remains of my classmates, attending this university may not seem worth it to me.