In my last post about New York regional rail schedules, I covered the New Haven and Harlem Lines of Metro-North and the Main Line and Hempstead Branch of the LIRR. I was hoping to cover more lines tonight, but due to time constraints only the Hudson Line is available.
This post should be viewed as considerably more accurate than the previous one, because I’ve obtained a Metro-North track chart with exact curve radii. I had to use measuring tools in the previous posts, and although the results were generally accurate, they were not completely so, and a few short, sharp curves cost a few more seconds than depicted. I do not believe the total slowdown between New York and either New Haven or Southeast to be worse than one minute relative to the track chart, but it is a slight slowdown, more than countermanding my tendency to round all fractional seconds up in speed zones.
One key difference with my last post is that the Hudson Line is not entirely electrified. It is only electrified south of Croton-Harmon; farther north, trains run with diesel locomotives, changing to electric mode only in Manhattan. My timetable assumes electrification. This is a project Metro-North should be pursuing anyway, since the outer Hudson Line is one of the busiest diesel lines in New York, alongside the outer Port Jefferson Branch and the Raritan Valley Line.
This lack of electrification extends to part of the express tracks south of Croton-Harmon as well. As a result, this schedule, while relying on cheap investments, is not quite the near-zero cost improvement on the express line. On the local line it is, since the trains are electrified.
As before, I am not assuming any curve is straightened, merely that track geometry trains fix the tracks to have higher superelevation (150 mm) and that trains run at 150 mm cant deficiency rather than today’s 3″. In metric units, this means acceleration in the horizontal plane is 2 m/s^2, so curves obey the formula
One big-ticket item that Metro-North should look into, in addition to completing electrification, is grade-separating the interlocking at CP 5, between the Hudson and Harlem Lines. The flat junction is extremely busy – it may plausibly have higher peak throughput than the flat junctions that plague South London’s commuter rail network – and hinders a simple 2-tracks-in, 2-tracks-out operation. This is not strictly speaking a speedup, but I would be more comfortable writing aggressive, high-frequency timetables if trains did not conflict at-grade.
Local trains run up to Croton-Harmon, making all stops.
|Station||Current time||Future M-7 time||Future Euro time|
The 9-minute interstation between Ossining and Croton-Harmon represents end-of-line schedule padding – in the southbound direction, trains are scheduled to take only 4 minutes.
Observe that the travel time difference is smaller than on the other lines presented in my previous post. Current equipment could shave 21% off the travel time, which is considerable but a far cry from the 33-40% elsewhere in the system. The reason is that the Hudson Line is maintained to higher standards, with cruise speeds of 80 mph on much of the line; I am assuming a speedup to 160 km/h, but the stop spacing along the Hudson is so short that trains can’t even hit 160 km/h while accelerating. The curves are still insufficiently superelevated – the Spuyten Duyvil curve where the fatal derailment happened has only 2.5″ of superelevation – and trains are only rated for low cant deficiency. However, the other aspects of the speedup on other lines are less conspicuous.
I also suspect that there is less schedule padding on the Hudson Line than on the other lines. Its frequency is lower, the line is four-track for most of its length, and the one significant flat junction equally affects the other two Metro-North mainlines. So the schedule may already be stable enough that padding, while considerable, is less outrageous than on the LIRR.
Express trains on the Hudson Line run a variety of stopping patterns, especially at rush hour. The line’s infrastructure is set up for intermediate express stops at Harlem, Marble Hill, Yonkers, Tarrytown, Ossining, and Croton-Harmon, but the standard off-peak pattern makes slightly fewer stops. My assumption is that all the above stations will receive express service.
|Station||Current time||Future M-7 time||Future Euro time|
This is a 35-38% reduction in travel time while making four more stops, two on the inner part of the line and two on the outer part that currently only see occasional seasonal use for hiking trails. The explanation for this is simple: the rolling stock used today is not M-7 EMUs but diesel locomotives. Rush hour trains running nonstop between Manhattan and Beacon connect Grand Central with Poughkeepsie in 1:36-1:37, a stop penalty of about 2.5 minutes, twice as high as what a European regional EMU can achieve at a top speed of 160 km/h.
Moreover, the 80-90 mph speed limit, which is dead letter on local trains for most of the way because they stop so frequently, consumes a few minutes relative to 160 km/h when trains run nonstop for long stretches. Thus, an increase in top speed is necessary in addition to an increase in curve superelevation and cant deficiency.
What about Grand Central?
My schedules consistently depict 6-minute trip times between Grand Central and Harlem, compared with current timetables that have them do it in 10-11 minutes. On most of the line, the top speed is the same – 60 mph, against 100 km/h in my timetable. The difference is entirely in the last mile out of Grand Central, where the limit today is 10 mph for no good reason.
The constrained environment of Grand Central does not leave room for high-speed switches. Nonetheless, the existing switches, called #8 switches, have a curve radius of about 140 meters, which is good enough for 40 km/h with no superelevation and a cant deficiency of 150 mm. American switches are generally rated for twice their number in miles per hour, assuming no superelevation and a 2″ cant deficiency; but higher cant deficiency is possible, and is really important as the difference between 25 and 40 km/h for a few hundred meters is considerable.
Moreover, 40 km/h is only the governing speed for a very short distance, about half a kilometer. Farther out, trains can always take the straight direction on turnouts, with one exception, turnout number 309B on the southbound local track (track 4), which is a triangular switch, i.e. one without a straight direction. Fixing the switch to have a straight direction from track 4 to track J, the westernmost approach track to the lower level of the station, should be a priority, plausibly saving 3 minutes for all trains using this track.
With trains taking the straight direction wherever possible, the central express tracks in the Park Avenue Tunnel (tracks 1 and 2) should exclusively feed the upper level, and the outer local tracks should exclusively feed the lower level; this way, there would not be any conflict. The station was originally designed for local trains to use the lower level and express trains to use the upper level, so this is nothing new, just a more rigid way of running service than today. Each of the two levels has ladder tracks permitting access to about 10 platform tracks, which is more enough for a train every 2 minutes; for reference, the 4 platform tracks of Haussmann-Saint Lazare on the RER E turn 16 trains per hour at the peak today, and were constructed with the ability to turn 18.
The upshot is that very little station reconstruction is needed at this stage. Some reconstruction is required for through-running, as it would require all approach tracks to go to the lower level, but even that would be much cheaper than the through-running tunnels. But with terminating service, only one switch needs to be changed. This is not expensive; the limiting resource is imagination to do better than today’s slow service.