KOMANOFF: Investing Congestion Revenues in Better Train Signals Could Save New Yorkers Lots of Time

A timer signal on the Williamsburg Bridge.
A timer signal on the Williamsburg Bridge.

Gov. Cuomo and legislative leaders are looking to congestion pricing to generate $1 billion a year to support $15 billion in capital spending on transit, mostly on subways. What if that revenue stream went to install Communications-Based Train Control on as many lines as possible?

I’ve taken a shot at quantifying the benefits, and they appear huge. By my estimates, $15 billion could pay for NYC Transit to install CBTC on around a dozen, or nearly half, of the city’s subway lines, cutting passenger travel time on those lines by 20 percent. Averaged across the entire system — a calculation that necessarily dilutes the per-trip savings — a typical trip on the subway would go 10-11 percent faster. That speed-up will save riders a million and a half hours a week, or nearly 80 million hours a year.

Not just straphangers but drivers too stand to save considerable time with the investments in CBTC, as the switch of some trips to more-reliable transit thins out traffic on city streets, highways and bridges.

Before I detail my calculations, it’s worth asking how plausible is a scenario investing $15 billion in CBTC. Needless to say, it’s unlikely that CBTC will grab every dollar of congestion revenues, notwithstanding that signal issues account for half of subway delays, according to the Regional Plan Association, the transit research and advocacy group whose insistent and expert research helped make CBTC “a thing” in recent years:

RPA collected delay data published by the MTA daily from September 2016 to June 2017. Signal-related delays accounted for over half of the delays (54 percent) during this period. Second was the MTA’s generic category “incidents” — a catch-all that also likely includes more signal-related issues. Other mechanical systems accounted for a much lower share of overall delays — tracks (16 percent), switches (4 percent), rolling stock (3 percent) and power (less than 1 percent).

(Save Our Subways: A Plan to Transform New York City’s Rapid Transit System, June 2018, p. 23.)

But it’s possible that the budget bill that will pass in Albany by March 31 could include more than the default billion a year in new monies for the MTA, especially with new taxes on weed and pricey pieds-a-terre on the agenda. And if congestion tolls do pass, the legislature could further pad the revenue by retooling the for-hire vehicle surcharges that went into effect last month.

Moreover, replacing the subways’ ancient “fixed-block” analog signals with digital CBTC is widely seen — as in this MTA video and the Regional Plan Association’s ”Moving Forward” report — as the city’s most-burning transportation infrastructure priority. So even as a hypothetical, it’s worth seeing what New Yorkers could get from a decision to dedicate a billion bucks a year to CBTC. NYC Transit president Andy Byford’s 2018 “Fast Forward” pledge to compress from four decades to just 10 years the time to equip all 26 subway lines with CBTC remains a linchpin of hopes for 21st-century transit in New York.

Nevertheless, this being NYC and the MTA being the MTA, 100 percent CBTC has never gotten an official price tag; nor have the potential travel time savings from CBTC been estimated. Recently, with funding from an anonymous transit advocate, I set about filling the data gaps. Here are my findings:

  • Based on experience installing CBTC on the Canarsie Line (L train) and Flushing Line (7 train), equipping a mile of track with CBTC costs $45 to $50 million (in constant 2019 dollars).
  • Excluding lines shorter than 10 miles, which account for a very small fraction of total track-miles, the average subway line is 26 miles, a length that will require nearly $1.25 billion each to install CBTC.
  • $15 billion invested in CBTC — roughly the capital that can be secured with a new billion dollar a year revenue stream — could pay for installing CBTC on a dozen lines totaling 315 track-miles, or roughly 45 percent of the system’s 696 track-miles.
  • CBTC can cut 20 percent from the duration of a typical subway trip; I calculated that figure taking into account lower headways and better spacing between trains, fewer signal-caused delays, enhanced flexibility to mitigate issues as they occur, higher rolling speeds and shorter station dwell times from reduced crowding.
  • Prorating those savings over the entire system, the $15-billion investment in CBTC enabled by the $1 billion a year revenue stream will shorten the duration of an average subway trip by 10 percent.
  • Traveling by subway consumes an estimated 833 million hours a year of New Yorkers’ time. Dedicating $1 billion a year to install CBTC can shorten that time by 80 million hours.
  • Per day, the time saved is 216,000 hours, a daily savings worth $3.5 to $4 million to riders, based on a wage-based average value of time of $17.23.

To be clear, these hours of time savings are for the dozen lines that can be converted to CBTC with $15 billion. Making CBTC system-wide will slightly more than double them, but of course will cost well more than the initial $15 billion in capital that congestion pricing is intended to make available for transit.

If you’re familiar with my quantitative work on driving, transit and pricing, you know that I obsessively break travel costs and data into their component parts which I combine in my ever-evolving BTA spreadsheet (8.5 MB Excel file, downloadable here; see especially the new CBTC tab). My most important methods and assumptions follow:

CBTC costs to date

  • According to MTA records, the authority opened CBTC-install budget lines in 1996 for the Canarsie line and in 2004 for the Flushing line. Adjusting each year’s expenditures to constant dollars — a must for extrapolating from empirical data — the installations cost $56.4 million a mile (Canarsie) and $38.7 million a mile (Flushing) in 2019 dollars.
  • The marked drop in CBTC costs from the Canarsie install to Flushing cries out for explanation. While it’s tempting to discount the Canarsie data on the premise that it was bloated by first-time costs, it’s also possible that the financials for Flushing are incomplete. Lacking more info, I conservatively averaged the costs to project that future CBTC installations will cost $47.6 million a mile (in 2019 dollars).

Smoother running with CBTC

  • CBTC builds an interconnected network of trains and signals in which real-time tracking of trains is possible and accessible for riders. This central information network will enable NYC Transit to react in real time to both breakdowns and increased demand by rerouting trains. (With antiquated fixed-block signaling, a train’s final location is set beforehand and all tracks are unidirectional.) Individual issues can be localized without snowballing.
  • I assume that on lines with CBTC, during the 7 a.m.-7 p.m. period accounting for three-quarters of all subway trips, station “dwell times” will drop by ten seconds, rolling speeds will rise 25 percent, and trains per hour will increase to an average of 28, from 23 at present.
  • These assumptions translate mathematically to 20.4 percent quicker trips on the lines that will get CBTC (paid for by the $15 billion in capital backed by the $1 billion a year revenue stream). That equates to a 9.6-percent system-average shortening in trips and, in turn, a 10- to 11-percent increase in subway trip speeds (recall that velocity = distance/time, so that percentage shortenings of time give rise to slightly higher percentage gains in speed).

Other assumptions along with my calculations and sources are detailed in the BTA spreadsheet. One result not shown there — it takes a bit of tweaking with the model — is that drivers will save 40 million hours a year from lighter traffic as improved subway service reduces use of for-hire vehicles and private cars.

But the bigger picture is that CBTC will enable NYC Transit and the MTA to begin to unify the subway under a single network of connections allowing better communication and efficiency. Even for me, the ultimate benefits of that are hard to quantify.

Transit advocate and enthusiast Michael Kendall greatly assisted in the research underlying this post.


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