It’s a commonplace that Amtrak can’t expand service frequency or even lengthen consists because it has a shortage of rolling stock. This is usually what is meant by “Amtrak is at capacity,” since there’s ample room to run longer trains. So I’ve been trying to investigate how much rolling stock constraint Amtrak actually has.
The sharpest shortage would be present in the Acela trains, since they have high seat utilization – about 60-65%, vs. 45-50% on the Regional. There are ten daily Acela roundtrips north of New York and fifteen south of New York, so at worst, fifteen consists are sufficient. The maximum frequency is hourly; the Boston-Washington trip time is just over 6.5 hours, so fourteen consists should be enough to provide more service than is available today, and with the current mix of hourly and two-hourly service currently used north of New York, thirteen are enough. There are twenty consists, so there are more than enough spares, and rolling stock does not actually limit capacity.
The New York-Washington trip time is 2:47-2:52, and the turnaround time is 8-13 minutes, which means that six trainsets could provide one extra hourly train. This implies Amtrak could do one of three things with the seven spares:
1. It could increase the frequency south of New York to half-hourly, except in the peak one hour in which the North River Tunnels are at capacity with current signaling.
2. It could couple two trainsets together. It could also mix this with option 1, depending on North River Tunnel capacity – i.e. couple two trains together just during rush hour and run every 30 minutes otherwise, and use the seventh spare to cover the mismatch in peak scheduling if necessary.
3. It could cannibalize the cars of some of the spares to lengthen the other consists from six to eight cars – or even ten if service to Boston is strictly two-hourly, which would require only ten consists.
For the most part, the platforms are long enough for the reconfigurations in options 2 and 3. All platforms are long enough for eight cars, and it’s fairly trivial to lengthen the few Acela platforms that are only eight-car long to ten cars except New London. All from New York south are long enough for twelve cars, used in the Pennsylvania Railroad days; Washington’s long platforms are low-floor, but it suffices to convert just one to high-floor. Option 2 really requires fourteen-car platforms – there are twelve cars but two power cars are in the middle – but the platforms are long enough at New York, Philadelphia, and Washington, and at the other stations people at end cars could walk to an adjacent car, a practice already used at the low-floor Regional stations in Connecticut and Rhode Island.
Note that in option 3, it’s in principle possible to make all service north of New York half-hourly, and either run all trains in double or cannibalize trains to create twelve-car consists. The problem with this is not platform length, but the complete lack of spares throughout the day.
There is, in other words, capacity for doubling Acela service south of New York, where the highest demand is. If Amtrak doesn’t provide this service, it could be an artificial shortage meant to keep prices high, or just insufficient demand for the quality of service. And if it cries capacity, it’s just after more money.