One of my go-to datasets for analyzing American intercity traffic is the Consumer Airfare Report. It reports on average airfares paid for domestic airline traffic, and on the way gives exact counts for O&D traffic between any pair of cities in the contiguous United States. Six and a half years ago I used this dataset to look at potential demand for high-speed rail, back when high-speed rail was still a topic of conversation in American politics, and a few days ago I got curious and looked again.
Unfortunately, the Consumer Airfare Report is no longer available as an easily downloadable table, due to web design horror. The relevant table, Table 6, used to be downloadable per quarter; today the only version lumps all data going back to 1996 and is 100 MB. Here are two cleaned up versions in .ods format, one a 40 MB table going back to 1996 and one an 800 KB table of just the most recent quarter available, the second quarter of 2018. The files lump all airports in a metro area together, such as JFK and Newark, and reports data in ridership per day; be aware that in the smaller file I repeat every city pair, one for each direction, making it easy to sort by city to figure out each city’s total air traffic, which means that just summing up ridership for all city pairs together yields double the actual traffic. In this post I’m going to compare data from 2018 to data from 2011, the year used in my previous post.
Air traffic is increasing
In 2011 Q3, the total volume of domestic air traffic in the US was 1,020,673 per day. By 2018 Q2, it had risen to 1,303,397. A small proportion of this increase is seasonality – Q2 is the busiest – but most of it is real. Here is a table of air traffic and average distance flown (in miles) by quarter:
Long-distance air traffic is especially increasing
The proposition of high-speed rail is that it can replace short-haul flights. A plane averages about 1,000 km/h but incurs considerable taxi, takeoff, and landing time, and passengers also have considerable airport access and egress times, including security and other queues. High-speed trains average about 200-250 km/h, but need no security – a well-run system allows passengers to show up at the station less than five minutes before the train departs – and have much shorter access and egress times as stations are located near city centers.
The above table shows a small increase in average distance flown, about 2% since 2011. However, this masks patterns in the largest cities. New York-Los Angeles traffic grew 30%, compared with 23% in national traffic growth; it is now barely behind New York-Miami (with West Palm Beach separated out) for third busiest American air city pair, the first being far and away Los Angeles-San Francisco.
We can look at the change in the proportion of traffic that can be served by HSR in the largest six American air markets since 2011; consult my post from 2012 for the exact definitions of which corridors count within which buckets – there are some revisions and fixed to be made, but I’ve not done them in order to keep the list of city pairs constant. Las Vegas is no longer ahead of Boston, and Dallas is a fraction of a percent below Boston as of 2018.
|City||Traffic (2011 Q3)||Traffic (2018 Q2)||< 3:00 (2011)||< 3:00 (2018)||< 5:00 (2011)||< 5:00 (2018)|
In the East, short-distance markets have shrunk, in relative terms. Observe that in Chicago the entire difference is within the 3-hour radius, including the spokes of any Midwest HSR network, where air travel has srhunk 12.6% in absolute terms, whereas the 3-to-5-hour annulus, including farther away cities like Atlanta and New York, has not only grown but kept up with Chicago’s overall domestic air travel volumes. But in New York, Washington, and Boston, both the 3-hour radius and the 3-to-5-hour annulus have shrunk, reflecting flights to intermediate Midwestern cities east of Chicago as well as to the South; Boston’s 3-to-5-hour annulus has shrunk 6% in absolute terms.
California holds steady
Since 2011 there has been an increase in air travel to California, especially San Francisco. Los Angeles-San Francisco, once the second largest air market in the US behind New York-Miami, is now far ahead of it, and on its strength, the share of air travel out of Los Angeles and San Francisco that’s within HSR radius has held up.
California’s HSR problems are not about whether there’s demand for such infrastructure. There clearly is. The problems are exclusively about construction costs. But as the state’s economy grows, demand for internal travel is increasing, making HSR a better proposition.
What does this mean for HSR?
The cynical answer is nothing, because in an America where even high-spending Green New Deal proposals neglect HSR and focus on electric cars, it’s unlikely there will be a political effort to build anything. Even Amtrak seems content with justifying capital expense on grounds of climate adaptation rather than reducing trip times.
That said, in the event of a concerted national effort to build HSR, the changes in travel patterns this decade suggest some changes on the margins. California and Texas grow in value while the Midwest falls in value.
In the Midwest, the core lines remain strong, but more peripheral Midwestern lines, say a bypass around Chicago for cross-regional traffic or improved rail service due west toward Iowa, are probably no longer worth it. The Cleveland-Columbus-Cincinnati corridor may not be worth it to build as full HSR – instead it may be downgraded to an electrified passenger-primary corridor (as I understand it it already has very little freight).
There is asymmetry in this situation in that there aren’t a lot of peripheral lines in California and Texas that are becoming interesting now that these states’ economies are bigger than they were when rail advocates first came up with maps in the late 2000s. There is still far too little traffic to justify stringing HSR from Las Vegas to Salt Lake City or from Sacramento to Portland under the mountains. In Texas, there has been a shift from the T-bone alignment to a more triangle-shaped network, since a direct Dallas-Houston line is already under construction, but beyond the Texas triangle, tails like Dallas-Oklahoma City and Houston-New Orleans aren’t getting stronger – Houston-New Orleans air travel volumes are actually down from 2011, though Dallas-New Orleans volumes are up.
The core lines, of course, don’t change. The Northeast Corridor is still the most important corridor, the next most important are still tie-ins extending it to the south and west, and the following is still California HSR. But the dreams of a nationally connected network, or at least a connected network in the eastern two-thirds of the US, should be cast aside – the in-between links, always peripheral, have weakened in this decade.