Earlier this week, I tweeted this:

There are two, largely independent backstories to this tweet. The first is that I’m going back to Helsinki next week to attend the 75th World Science Fiction Convention, and when I was in Helsinki last March and April, I was inspired to write a whole lot on that city’s excellent transit system (see post 1 and post 2). The second reason is the current Commonwealth Ave. overpass reconstruction project in Boston, which was projected to have some deleterious effects on my commute, and which made me take a more serious look at the possibility of taking commuter rail into work — at least for the duration of the construction. I ultimately decided that paying $22.50 a day plus an extra hour and a half of my time was not worth it, given that my car commute is out of peak hours and costs about the same when you factor in parking, tolls, and fuel. But that made me think about the state’s current level of (dis)investment in public transportation infrastructure and what it would take to get me out of the car, on those days when schedule or weather don’t allow for a bike commute (which is more than half the year). I concluded that commuter rail would have to offer sufficiently frequent service, even at the hours I work, and get me from Framingham to Kendall Square in less than 45 minutes — which is not as good as my car commute, 35 minutes parking space to parking space, but is at least in the same ballpark, and if implemented properly would be significantly less variable.

How could you do that, given that the current Framingham-to-South Station run is scheduled to take 49 minutes, and then there’s the Red Line beyond that? The answer, as it turns out, is pretty simple: Electric Multiple Units, or EMUs — a standard passenger rail technology throughout the world, which (when combined with the appropriate investments in track, overhead electrification, and high-level platforms at stations) can significantly reduce travel times by accelerating much faster than conventional locomotive-hauled trains, especially the diesel locomotives currently used throughout the MBTA commuter rail network. Helsinki has such a system (actually the only commuter-rail network in Finland — the rest of the country isn’t dense enough to support it), which clearly demonstrates that a cold climate in a maritime city is no obstacle to successful implementation. Helsinki’s system provides service on multiple lines from the central business district to the airport — a distance similar to my commute — every fifteen minutes. Helsinki uses a customized cold-weather version of the Stadler FLIRT for most of their services, and I know that a number of US transit agencies have ordered FLIRT equipment for their own commuter rail services, so I looked up the performance details and sat down with a simplified line diagram and a calculator to figure out what that service would look like.

The FLIRT is typically configured for a maximum speed of 160 km/h (99 mi/h). At a typical acceleration of 1.02 m/s/s (depending on configuration, this can vary from 0.8 to 1.2 m/s/s) it takes 43.5 seconds and about six tenths of a mile. (Actually, I chose that acceleration value to make it work out to exactly 0.6 mile or 965 m!) I’m assuming that the entire Framingham–Worcester line is rated for 99 mi/h. (It’s not, but remember, we’re what-ifing an investment in better service, and that would involve electrification, trackbed improvements, new platforms, and possibly some grade crossing improvements or eliminations.) I also assume that there’s a “terminal zone” between South Station and the future West Station where speeds are limited by interlocking (junctions with other lines and switching into South Station). I assume that the train can accelerate and decelerate at the same rate, and that this would be done in practice (probably not) just because it makes the math come out easier. Finally, I assume average dwell time at each station is 30 seconds — and since I don’t take the commuter rail right now I don’t know if this is overly optimistic or pessimistic.

So what does this schedule look like? Well, consider, for comparison sake, the current MBTA train 552, which leaves Worcester Union Station at 8:00 AM and arrives at South Station at 9:06, for a scheduled travel time of one hour and six minutes. This train runs express from Worcester to Yawkey, so it only has two station stops aside from the termini — and it creates a huge gap in the schedule for everyone else, because the Framingham–Worcester Line is only two tracks and there’s no way for an express to pass a local train making an intermediate station stop. Now compare that with the following schedule, making all station stops:

Change ends at South Station and the same trainset leaves for Worcester at 9:00. What’s more, you can start a second trainset at Framingham, also at 8:00, and it gets to South Station at 8:27, so it can become the 8:45 outbound. (In the future, of course, you’ve also converted the Grand Junction branch and it gets Framingham residents a one-seat ride to Kendall in 25 minutes!) Repeat the same pattern every half hour from 6 AM to 11 PM, and you’ve made an enormous improvement in regional mobility and given thousands of people a practical reason to get out of their cars and onto the train. It takes, I think, four trainsets to run this service, not counting spares shared with other lines.

Well, it was a good dream, anyway. We all know that something this useful has absolutely no chance of ever making it through the MBTA bureaucracy or Beacon Hill. Numbers available on request if you want to check my math.