In constructing timetables, TransitMatters has relied on a combination of simulations, acceleration and deceleration information, and industry best practices from other countries, chiefly Switzerland. Caltrain, the commuter rail system connecting San Francisco and San Jose, is currently in
the process of electrifying its service. Local rail activist Clem Tillier ran simulations using public technical specifications and found that bilevel EMUs would connect San Francisco and San Jose 15 minutes faster than the current diesel locomotive-hauled trains. Electric locomotives would only save 1 to 2 minutes over diesel locomotives over the 19-stop local schedule. Our plan, with lighter single-level EMUs, saves more time per stop, especially since the MBTA has less powerful diesel locomotives than Caltrain. The speed and acceleration data we use come from the FLIRT, a single-level Swiss-made EMU. The top speed can be up to 125 mph, but we use the more typical 100 mph. There are public videos of FLIRT acceleration to 100 mph 34 and deceleration from 60 mph.35 These give enough information to compute the “stop penalty” at each top speed—that is, the time the train loses from decelerating to a stop and then accelerating back to line speed, excluding dwell time at the station:
The dwell time at each station is 30 seconds. This is based on many observations of train performance in Paris and in Zurich. In Paris, the observed trains have level boarding and many doors. In Zurich, the trains are bilevel and have two door pairs per car, some with level
boarding and some without; all trains have wide doors and open circulation, permitting short dwell times.
The only exceptions observed to the 30-second dwell time rule are the busiest city center stations. At Paris’s Gare du Nord, rush hour trains on the RER B Line, with four pairs of doors per car, have about 500 passengers getting off and 500 getting on; the dwell time is about 60 seconds. Based on this, we believe Regional Rail should have 60-second dwell times at South Station, Central Station, and North Station, and 30-second dwell times everywhere else.
Finally, to allow trains to recover from delays, schedules must be slightly padded. In Switzerland, the padding factor is 7%, since the trains are reliable and dwell times are predictable. This is the value we use; in contrast, American commuter operations pad 15% or even more, especially on lines with complex express service patterns.
The North-South Rail Link has had a few different variants in official proposals. Some variants have one tunnel and two tracks, others have two tunnels and four tracks. We back the four-track option, for two reasons. First, the tunnel portals to the south of the South Station are complex and constrained, and it is not possible to connect all lines to just one tunnel; in engineering studies going back to the 1990s, one tunnel portal would
always connect to Back Bay and the Providence and Worcester Lines, and the other to South Bay and the Fairmount and Old Colony Lines.
Second, there is not enough capacity with just two tracks. The maximum capacity on a two-track railroad is about 48 trains per hour—a train every 75 seconds—but only on driverless metro lines isolated from the national rail network. Commuter Rail lines top out
at about 30 trains per hour in Paris, Tokyo, Berlin, and Munich—a train every two minutes. A more typical value, given the extent of branching expected on Regional Rail in Boston, is 24 trains per hour, a train every 2.5 minutes.
With ridership growth coming from better service, we expect peak travel demand to be well over 24 trains per hour across all lines entering Boston from the south. We estimate that peak Regional Rail traffic, across all lines feeding South Station today, would be 32-36 trains per hour. Calculating the same figure for the lines feeding North Station is more difficult, because Commuter Rail today has lower mode share on the north than on the south (most downtown jobs are closer to South than to North Station), and NSRL would change this, but total commute volume into Boston is about the same in the northern suburbs as in the southern ones.
We do not expect any capacity constraints except on the immediate approaches to North and South Stations, and on some segments shared with other types of trains such as the Providence Line, where any future high-speed rail service would require facilities for timed overtakes with Regional Rail.
The state Secretary of Transportation suggested at a December FMCB meeting that electrification could be problematic because of constraints on the signal system governing the minimum spacing between trains. In fact, what we propose has the opposite effect: repeating clockface schedules, with all-local trains, ensures that on the branches, trains are always 15 or 30 minutes apart; even the ancient legacy signals, requiring a few miles of separation between trains, can easily accommodate that. The only problems come from freight trains—but the only significant volumes of freight on the entire MBTA network are on the outermost portions of the Fitchburg and Haverhill Lines; the former (beyond Littleton) could just run trains every 30 minutes even at the peak, and the latter (beyond Ballardvale) is so short and has such slow passenger trains that mixing the two train types should not cause problems.
The NSRL tunnel should be built with three stations: South Station, Central Station/ Aquarium, and North Station. With large-diameter tunnels, it is possible to build stations entirely inside the tunnel, punching galleries between the two tunnels for cross-platform transfers. The NSRL project should set up these cross-platform transfers on the same model as in Hong Kong: Central Station should have same-direction cross-platform
transfers, while North and South Stations should have opposite-direction ones. This means people from the Back Bay portal could transfer cross-platform to the South Bay portal at South Station, for example going from Braintree to Back Bay or from Brockton to Boston Landing. On the north, people could similarly transfer at North Station, for example going between Brandeis and Salem.
We include a technical appendix for each of the MBTA’s commuter lines, explaining what needs to be done to upgrade it to Regional Rail standards, and what a future Regional Rail timetable would look like. The speed gains from electrification, top-line trains, level boarding, and the reduced padding coming from better reliability are very large: we estimate on average 40% speed gain, or 30% cut in travel time, even with the addition of some infill stops.
The MBTA is currently evaluating options for additional midday layover space, including land previously dedicated to West Station. With increased midday service frequency, the need to store trainsets close to downtown disappears, since overnight layover can be accommodated at yards near the ends of lines. The midday layover needs result from trains making only a single pair of trips—inbound in the morning peak and outbound in
the PM—a service pattern that Regional Rail would eliminate in favor of all day equipment utilization.The MBTA should proceed with the understanding that, with increased midday service and a North-South Rail Link, additional investments in expensive core facilities are unnecessary. Boston Engine Terminal(BET), the primary maintenance facility for the commuter rail system, is unable to perform service on south-side trainsets without a long, slow trip through the non-revenue Grand Junction line. With the North-South Rail Link, trains could simply run through from the south side to BET.