In my previous post, I showed how, in New York, high-speed rail can’t realistically be expected to reduce demand for travel much, and so to decongest its airspace something else is needed. The solutions are to reduce the number of slots, which means either moving them elsewhere (i.e. building relief airports) or increasing plane size. Although increasing plane size is desirable from an operational and environmental point of view, it has problems that make it harder than in Japan, where short-distance domestic flights use widebodies as large as the 747. In contrast, because short-distance air shuttles in the Northeast use very small planes, high-speed rail is a surprisingly promising way to reduce air congestion, despite my original implication.
The key to the plane size problem is this chart of the world’s top air city pairs, with Seoul-Jeju topping at nearly 10 million passengers per year. The chart mainly shows Asian city pairs; Europe and the US are not on the chart. The reason is that the chart considers individual airports, rather than city airspaces; data from within the US shows that there are city pairs that would make the list, all multi-airport. New York-South Florida is close to 20,000 passengers per day, or 7.1 million per year, but there are three airports at each end, and they are fairly evenly matched: the busiest of the nine airport pairs, LaGuardia-Fort Lauderdale, has just 3,500 passengers per day, too few to make the international list.
What this means is that if airlines offer any frequency, it’s harder to provide service with larger planes. Harder does not mean impossible, but this is nothing like the huge travel volumes between Haneda and Japan’s other major domestic airports. Larger planes soak up passengers very quickly: despite being the world’s busiest airport pair measured by seats flown, Tokyo-Sapporo has 23 flights per day, with 767s and 777s, compared with 60 for New York-Boston, mostly regional jets.
The other issue is competition between airlines. Tokyo-Sapporo is a duopoly between ANA and Japan Airlines. The busiest routes in the US have more companies, and if they don’t, then they’re dominated by a low-cost carrier, which will stick to narrowbodies to maintain fleet uniformity. The American competition, including the presence of low-cost carriers, lowers the fare: a random check of a roundtrip between Tokyo and Sapporo in early December gives me a fare of about $900 roundtrip, versus $80 one-way for New York-Chicago for the same check, or $171 on average.
However, the competition also means that if each airline wants to offer high frequency on its own, it must fly smaller planes. Even a plane every two hours works out to about 8 departures per day per direction; if the plane is a 787, it’s nearly 4,000 passengers per day in both directions. The busiest single-airline, single-airport pair in the US is American flying LaGuardia-O’Hare, at 2,400 passengers per day; this excludes connecting traffic, but connecting traffic will not by its own make the difference between LaGuardia-O’Hare and Tokyo-Sapporo.
To ordinary travelers the choice of airline doesn’t matter too much: there’s no difference between having two airlines each with flights that leave on the hour, and having each airline’s flights depart every other hours so that they overlie and create hourly frequency. At 6,300 passenger per day on all airlines, JFK-LAX has enough traffic as it is to run fifteen 787s per day in each direction. But other airport pairs not dominated by low-cost carriers, including those to South Florida, could only support three to five 787s.
More speculatively, good transit access to airports – including commuter rail through-running to allow easy travel from New Jersey and Westchester to JFK and from Long Island to Newark – could reduce the difference between Newark and JFK for the average traveler. This means that Newark and JFK could be lumped together. Business travelers may still want their hourly flights out of LaGuardia, but the rest could do with a flight out of each of JFK and Newark every two hours, alternating.
The problem is that it requires a massive rise in the transit mode share of airport access, because it is impossible to drive between JFK and New Jersey in a reasonable amount of time. That said, a political environment that taxed jet fuel to incentivize larger planes would also tax gas and induce a mode shift toward transit. In either case, LaGuardia would be outside this system, since connecting it to mass transit is expensive, and has little benefit other than airport travel; in contrast, commuter rail through-running is not only cheaper but also useful to people traveling to the Jamaica and Newark CBDs, who outnumber air travelers.
So on the busiest routes larger planes are feasible, but nontrivial. The final question should be how useful this exercise is. Each of New York’s three main airports has about a thousand aircraft movements per day – five hundred per direction. There are about 110 daily departures to Chicago, Miami, and Los Angeles, combined. Consolidation into larger planes can realistically cut about a third, or 3% of aircraft movements – a bit more at JFK, a bit less at the rest on account of low-cost flights. Fort Lauderdale and Palm Beach add another 50 between them, but they’re dominated by JetBlue. A few additional thick markets like San Francisco and Orlando add a bit more, but it can’t amount to more than 5% of the total.
In contrast, there are more than 40 daily flights to Washington, more than 60 to Boston (including Providence and Manchester), and nearly 30 to Philadelphia. Adding in the other cities within 3-hour HSR radius gives us about 300 departures per day, 19% of the aircraft movements. Most of those would see O&D air travel disappear, and even at the outer margin of the radius they’d see air travel greatly diminish. Connecting flights would also decrease, because of the relative ease of air/rail connections. Philadelphia would have no reason for an air connection to New York if people could take a train to the airport that were faster than flying; the same is true of Boston and Washington, though Boston is far enough and has no easy air/rail connection, so it might retain a handful of daily flights.
Although I could weasel and say that everything is needed – larger planes, relief airports, and substitution of short trips by HSR – the reality is that those are not equally significant. Not even close. My previous post’s analysis of New York’s air market papered over a large difference between the share of passenger traffic and the share of aircraft traffic that can be substituted by HSR, coming from the use of regional jets on short-range flights. (By the way, this is especial to New York; in California most short-range flights are run by Southwest and use 737s, and so at LAX, the share of short-range flights among both passengers and aircraft movements is the same, at 21%.)
So as it turns out, a significant portion of New York’s air traffic can be replaced, helping decongest the airspace. The total is close to a quarter, of which nearly 20% comes from HSR replacing the air shuttles, and an additional 3-5% could come from consolidation of domestic thick markets into less frequent flights on widebodies.