In 2011, Clem Tillier and Richard Mlynarik put out sample schedules for modernized Caltrain service, with an applet anyone could use to construct their own timetables. I played with it, and one of the schedules I made, a trollish one, had room for local and express regional trains, but not intercity trains; intercity trains would be slotted with express regionals, and make the same stops. This was a curious exercise: intercity trains would be high-speed rail, which should not slow down to make every express regional stop. But more recently, as I’ve worked on schedules for Boston and New York, I’ve realized that when the regional trains are fast, there is merit to slotting legacy (but not high-speed) intercity trains together with them.
The origin of this pattern is the problem of slotting trains on busy railroads. There are many lines that are not really at capacity, but cannot easily combine trains that run at different speeds. One solution to the problem is to build extra tracks and give the intercity trains a dedicated pathway. This works when there is heavy intercity traffic as well as heavy regional traffic, but four-tracking a long line is expensive; Caltrain and California HSR ended up rejecting full four-tracking.
Another solution, favored for Caltrain today instead of full four-tracking, is timed overtakes. I have argued in its favor for Boston-Providence and Trenton-Stamford for high-speed rail, but it requires more timetable discipline and makes it easier for delays on one train to propagate to other trains. It should be reserved for the busiest lines, where there is still not enough traffic to justify long segments with additional tracks (that would be four tracking Boston-Providence and six-tracking Stamford-New Rochelle and Rahway-New Brunswick), but there is enough to justify doing what is required to run trains on a tight overtake schedule. It is especially useful for high-speed trains, which tend to be the most punctual, since they use the most reliable equipment and have few stops.
But on lower-ridership intercity routes, the best solution may be to force them to slow down to the speed of the fastest regional train that uses the line. On the timetable, the intercity train is treated as a regional train that goes beyond the usual outer terminal. This option is the cheapest, since no additional infrastructure is required. It also boosts frequency, relative to any solution in which the intercity train does not make regional stops: since the intercity train is using up slots, it might as well provide some local frequency when necessary. These two benefits together suggest a list of guidelines for when this pattern is the most useful:
- The intercity line shouldn’t be so busy that a slowdown of 10 or 15 minutes makes a big difference to ridership relative to the cost of overtakes. Nor should it be especially fast.
- The regional line, or the most express pattern on the regional line if it has its own local and express trains, should have wide stop spacing, such that the speed benefit of running nonstop is reduced.
- The regional line should connect long-distance destinations in their own right, and not just suburbs, so that there is some merit to connecting them to the intercity line. These destinations may include secondary cities, airports, and universities (but airports would probably be intercity stops under any pattern).
- The regional and intercity lines should be compatible in equipment, which in practice means either both should run EMUs or both should run DMUs (locomotives are obsolete for passenger services).
Both Switzerland and Japan employ this method. In Switzerland, the fastest intercity trains in the Zurich/Basel/Bern triangle run nonstop. But intercity trains going north or east of Zurich stop at the airport, interlining with regional trains to create a clockface pattern of trains going nonstop between the airport and the city.
In Japan, high-speed services run on their own dedicated tracks, with separate track gauge from the legacy network, but legacy intercity services are integrated with express regional trains. An intercity trip out of Tokyo on the Chuo Line starts out as a regular express commuter train, making the same stops as the fastest express trains: starting from Shinjuku, the Azusa sometimes stops at Mitaka, skips Kokubunji, and stops at Tachikawa and Hachijoji. Beyond Hachijoji, some trains make regional express stops, others run nonstop to well beyond the Tokyo commuter belt. On the Tokaido Line, the intercity trains (the Odoriko) skip stops that every regional train makes, but they still stop at Shinagawa and Yokohama, and sometimes in some Yokohama-area suburbs.
In North America, there are opportunities to use this scheduling pattern in New York, Boston, and Toronto; arguably some shorter-range intercity lines out of Philadelphia and Chicago, such as to Reading and Rockford, would also count, but right now no service runs to these cities.
In Toronto, GO Transit already runs service to Kitchener, 100 kilometers from Union Station. For reasons I don’t understand, service to Kitchener (and to Hamilton, a secondary industrial city 60 km from Toronto) is only offered at rush hour; in the off-peak, commuter trains only run closer in, even though usually intercity lines are less peaky than commuter lines. There is also seasonal service to Niagara Falls, 130 km from Toronto. As Metrolinx electrifies the network, higher frequency is likely, at least to Hamilton, and these trains will then become intercity trains running on a regional schedule. This works because GO Transit has very wide stop spacing, even with proposed infill stops. Niagara Falls is a leisure destination, with visitors from all over the Greater Toronto Area and not just from Downtown, so the extra stops in the Toronto suburbs are justified. Right now, Niagara Falls trains make limited stops, about the same number in the built-up area as the express trains to Hamilton but on a different pattern.
There are no infill stops planned on Lakeshore West, the commuter line to Hamilton and Niagara Falls. It is likely that future electrification and fare integration will create demand for some, slowing down trains. The line has three to four tracks (with a right-of-way wide enough for four) and is perfectly straight, so as demand grows with Toronto’s in-progress RER plan, there may be justification for local and express trains; express trains would make somewhat fewer stops than trains do today, local trains would stop every 1-2 km in the city and in Mississauga. Intercity trains could then easily fit into the express commuter slots; potential destinations include not just Hamilton and Niagara Falls, but also London.
This is unfriendly to high-speed trains. However, Canada is not building high-speed rail anytime soon; if it were, it would connect Toronto with Montreal, using Lakeshore East, and not with points west, i.e. London and Windsor. London and Windsor are small, and a high-speed connection to Toronto would be financially marginal, even with potential onward connections to Detroit and Chicago. A Toronto-Niagara Falls-Buffalo-New York route is more promising, but dicey as well. Probably the best compromise in such case is to run trains on a four-tracked Lakeshore West line at 250 km/h; the speed difference with nonstop trains running at 160 km/h allows 15-minute frequency on each pattern without overtakes, and almost allows 12 minutes. Alternatively, express trains could use the local tracks to make stops, as I’ve recommended for some difficult mixtures of local, express, and intercity trains on the Northeast Corridor in New York.
In Boston, the Northeast Corridor is of course too important as an intercity line to be slowed down by regional trains. Thus, even though in other respects it would be great for merging intercity and regional service, in practice, overtakes or four tracks are required.
However, all other intercity-range commuter lines in Boston should consider running as regular commuter trains (electrified, of course) once they enter MBTA territory. These include potential trains to Hyannis on Cape Cod, 128 km from South Station; Manchester, 91 km from North Station; and Springfield, 158 km from South Station; as well as existing trains to Portland, 187 km from North Station. Hyannis, Manchester, and Portland all feed into very fast regional lines: my sample schedule and map have trains to Hyannis averaging 107 km/h and trains to Manchester averaging 97 km/h. Trains to Haverhill, the farthest point on the line to Portland with any Boston-bound commuter traffic, average 88 km/h.
Springfield is more difficult. The Worcester Line is slower, partly because of curves, partly because of very tight stop spacing in the core built-up area. Once under-construction infill is complete, Auburndale, 17 km out of South Station, will be the 7th station out, and another infill station (Newton Corner) is perennially planned; my schedule assumes 3 additional stations, making Auburndale the 11th station out. On the line to Hyannis, the 11th station out, Buzzards Bay, is at the Cape Cod Canal, 88 km out. There is room for four tracks for a short segment in Allston, but in the suburbs there is no room until past Auburndale, which constrains any future high-speed rail plan to Albany. Low-speed intercity trains would have to slow down to match commuter rail speed, because the alternative is to run commuter rail too infrequently for the needs of the line. Average speed from South Station to Worcester is 70 km/h, even with express diesels today, so it’s not awful, but here, slowing down intercity trains is a less bad option rather than a good one.
In New York, as in Boston, intercity trains fit in regional slots away from the Northeast Corridor. Already today there are intercity trains running on the LIRR, to the eastern edge of Long Island, much too distant from the city for commuter traffic. Those trains run nonstop or almost nonstop, and are infrequent; if the entire LIRR were electrified, and express trains were eliminated, locals could match the express speed today thanks to reduced schedule padding, and then some trains could continue to Greenport and Montauk providing perhaps hourly service. Service to Danbury and Waterbury on Metro-North is of similar characteristics.
The New Jersey end is more interesting. Right now, there is no significant intercity service there, unless you count the Port Jervis Line. However, New Jersey Transit is currently restoring service on the Lackawanna Cutoff as far as Andover, and there remain proposals to run trains farther, to Delaware Water Gap and Scranton. Those would be regular express diesel trains on the Morris and Essex Lines, presumably stopping not just at Hoboken but also at important intermediate stations like Newark Broad Street, Summit, and Morristown.
If service were electrified, those trains could run, again on the same pattern as the fastest trains that can fit the Morristown Line (where I don’t think there should be any express trains), going to New York and onward to whichever destination is paired with the shorter-range commuter trains on the line. The same is true of other potential extensions, such as to Allentown, or, the favorite of Adirondacker in comments, a line to West Trenton and onward to Philadelphia via the West Trenton SEPTA line. There’s not much development between the edge of the built-up suburban area at Raritan and either Allentown or the Philadelphia suburbs; but intercity trains, averaging around 90 km/h, could succeed in connecting New York with Allentown or with the northern suburbs of Philadelphia, where a direct train doing the trip in an hour and a half would be competitive with a train down to 30th Street Station with a high-speed rail connection.
The characteristics of intercity lines that favor such integration with regional lines vary. In all cases, these are not the most important intercity lines, or else they would get dedicated tracks, or overtakes prioritizing their speed over that of commuter trains. Beyond that, it depends on the details of intercity and regional demand. But by default, if an intercity line is relatively short (say, under 200 km), and not so high-demand that 200+ km/h top speeds would be useful, then planners should attempt to treat it as a regional line that continues beyond the usual terminus. Alternatively, the commuter line could be thought of as a short-turning version of the intercity line. Planners and good transit advocates should include this kind of timetabling in their toolbox for constructing integrated regional rail schedules.