South Station’s 13 tracks currently handle about 320 revenue trips per day, plus an additional 129 non-revenue trips per day that are required primarily due to the inherent inefficiency of a stub end terminal. With this antiquated arrangement, nearly 30% of all train movements in and out of South Station produce no revenue and no transportation benefit, while tying up equipment and crews, and even more importantly, valuable urban land that could be far better used.

At about the same time Massachusetts eliminated a rail link from the Central Artery Project, the city of Philadelphia completed the first such link in the United States, a 1.7 mile tunnel beneath the center city, linking its two main terminals, Suburban Station and Reading Terminal, known as the Center City Commuter Connector. Its 4 tracks currently carry more than 650 trains per day. These are revenue trips, and there is substantial capacity remaining for further service improvements. The fact that Philadelphia’s link is carrying more than twice as many revenue trips withless than 1/3 of South Station’s tracks, should be a wake-up call that we are on the wrong path with South Station Expansion.

How is this performance discrepancy possible?  MassDOT’s 2013 Fact Sheet for the South Station Expansion Project is remarkably direct in assessing the root cause of terminal congestion, namely that:

“South Station is a terminal station – literally the end of the line. This means that trains do not pass through but instead have to pull in and pull out of the station. For every one train, two movements are needed – one entering and one leaving the station. This only increases the complexity of managing the station.”   [South Station Expansion DEIR]

Plan of proposed development on the US Post Office site adjacent to South Station, showing that much of this very expensive waterfront site will be devoted to parking trains (new platforms are shown in orange), wiping out about 550,000 sf of useable area, and greatly complicating the construction process. The MBTA conceded in January 2015 that, as a result, the development is unlikely to make any financial contribution toward the cost of South Station Expansion.   [South Station Expansion DEIR]

Rather than addressing the root cause of this gross inefficiency, the Commonwealth is currently planning to add 7 additional stub-end tracks at South Station and 2 more at North Station, at a staggering cost of about $2 Billion. Leaving aside the cost, the addition of surface tracks simply compounds the inefficiency of the stub-end operations and adds precious little capacity for future growth. Rather than solving the underlying problem, this approach simply compounds it.

The difference between through-service and stub-end service can be compared to the difference between a bucket brigade and a water pipe. In the latter there is nearly continuous flow, with no reversing. In the former, half of the movements are wasted.

Summary of capacity needs and constraints at South Station in Boston. Note that South Station is at capacity with just 320 revenue trips per day, while Philadelphia's downtown through-stations carry more than twice as many revenue trips with less than 1/3 as many tracks, and with capacity to spare.   [MBTA South Station Expansion Project DEIR, Oct. 2014, p. 2-6]

We don’t have to look to Philadelphia for confirmation of this. Our own 2-track Red Line stations are able to carry as many passengers per day as our 13 track stub-end terminal at South Station. This can be explained by the “dwell times” and “headways” on the two systems – 25 minutes at the terminal, versus 3 to 4 minutes, or even less, for the run-through subway lines.

It is obvious from this example, and amply confirmed by the experience of the many cities that have built and are building run-through systems, that unification produces far more capacity than terminal expansion. And it does this while reducing the footprint of surface rail and improving service system-wide.

In addition to greatly increasing the capacity of our downtown stations, rail unification will also increase the capacity of our transportation system as a whole, by relieving pressure on the most heavily used transit lines, and by removing cars from the congested highways system. Of the 96,000 new riders per day attracted by the NSRL, 55,000 are diverted from highways.