There’s a pretty bad mistake in my post about MBTA-HSR compatibility: the length of the Boston-Providence line is 70 kilometers, not 67 as stated in the post. In my defense, 67 (42 miles) is what the official mileposts say, on Wikipedia and on the catenary poles along the line. In calculating travel times I used a mix of milepost and Google Earth data, leading me to slightly understate the travel time difference between future high-speed trains on the corridor and improved regional rail. The difference is small, but is important for choosing overtake locations.
The correct technical travel times for nonstop 300 km/h HSR and 160 km/h regional trains making all current MBTA stops are 19.25 and 38.75 minutes, respectively. It’s offset by just half a minute from the technical time I originally thought was correct, but more of the difference occurs near Providence than near Boston. The upshot is that the single-overtake option in Sharon is loose in the north, allowing an additional Boston-area stop, and extremely tight in the south, requiring 200 km/h trains and not necessarily allowing regional trains to stop at Pawtucket.
This doesn’t directly affect Woonsocket trains, for which my example schedule is based on Google Earth lines and should be considered accurate given the assumptions. However, in a comment, I’ve been linked to a 2009 Providence Foundation study of the feasibility of a regional train to Woonsocket, under present FRA regulations, achieving similar trip times to those I propose but with fewer stops. The service proposed is very good relative to the regulatory and organizational environment it has to deal with – the projected cost per rider is about $25,000, fairly low by US standards.
The Providence Foundation study also includes a timed transfer at Pawtucket between Woonsocket and Boston, something I did not originally think of. Since the exercise on this blog assumes organizational competence on the MBTA’s behalf, we can choose an overtake option that makes this work optimally with short turnaround and transfer times. We should also include fare integration in the scenario, something that doesn’t currently exist even just between the MBTA and Amtrak. Under some HSR operating scenarios, it could charge the same fare as low-speed rail on the same corridor and have integrated ticketing, making a Pawtucket transfer less useful than an HSR transfer at Providence. Under others – for example, an HSR fare surcharge as currently practiced on the Shinkansen or ICE – it is not possible, and while integrated ticketing is still possible and desirable, cost-conscious commuters would need a solution not involving intercity trains.
It turns out that a single-overtake option does not accommodate Pawtucket transfers well, even if a Pawtucket stop could be squeezed into the schedule. Consider the following 200 km/h schedule north of Providence, with the 7% pad, rounded to a half-minute:
|Sharon||Arrive 0:33:30, Depart 0:37:30|
It’s possible to replace Readville with Forest Hills; the point is that there’s room in the schedule for it. The times above were chosen to make :00 the symmetry axis – i.e. southbound regional trains leave Boston at :02. Moving the symmetry axis is possible but requires giving up through-service to Warwick – the timetable would be too tight. Under this schedule, southbound regional trains would arrive in Pawtucket at :45, and HSR trains would arrive immediately after, at about :48; thus, southbound Woonsocket trains would arrive at the earliest at :50 and :20, timing them to just miss the northbound connection to Boston. Clearly, under such an option, the only way to provide satisfactory Woonsocket-Boston service is to connect to HSR at Providence.
The two-overtake schedule looks much better. It’s a tighter fit for Woonsocket trains between the faster MBTA and HSR trains, but once they fit, the transfer works well. Consider the following 160 km/h two-overtake schedule, with four-tracking between Readville and Route 128:
|Attleboro||Arrive 0:18, Depart 0:22|
|Route 128||Arrive 0:40, Depart 0:41|
|Readville||Arrive 0:43, Depart 0:45|
Southbound MBTA trains arrive at Pawtucket at :49:30 and southbound HSR trains pass by Pawtucket at :44. Southbound Woonsocket trains have a window of about 1.5 minutes – they can arrive at Pawtucket between :51:30 (after the MBTA) and :53 (before the next HSR) to fit in on the same track pair used by the MBTA and HSR – but within that window they have a convenient transfer: 2.5-4 minutes to the next northbound MBTA train, at :55:30. Note that even in the off-peak, when MBTA trains would come every 30 minutes rather than every 15 minute, this works – we can just shift the slots used by MBTA and Woonsocket trains. Earlier arrival is good for the entire turnaround schedule for Woonsocket trains, which based on trip times would “like” to arrive at Providence at :58 and at Pawtucket at :51, though, if the Mineral Spring stop for Woonsocket trains is dropped, then :52 arrival is very comfortable at all ends.
The inclusion of Woonsocket service also favors ant6n’s proposed no-overtake schedule, in which Boston-Providence trains run at 200 km/h and skip stops near Boston and let Stoughton trains provide local service, and trains run every 20 minutes. It’s tight if MBTA trains stop at Pawtucket, but gives Woonsocket trains ample time for anything. Assuming a Pawtucket stop can be squeezed, for :58 Boston arrival northbound regional trains would depart Pawtucket at :27, i.e. southbound MBTA trains would depart at :33 and HSR would pass by at :35, right on their heels. Woonsocket trains could be slotted anytime between :37 and :47:30, where :41 would be optimal for their own turnaround times and :45-46 would provide the shortest robust connection.