Quote:
Originally Posted by Mr Downtown
^There's catenary, track, substations, ticket machines, and signals to be maintained. The vehicles require more expensive maintenance. They deadhead more than buses.
As for energy usage, here are some numbers from the Transportation Energy Data Book, 28th Edition, U.S. Energy Dept.
BTU of Energy Used per Passenger-Mile of Travel
7605 light rail average all systems
4800 light rail serious urban systems*
4315 transit buses
3700 heavy rail
3514 autos
1853 motorcycles
*estimated from Figure 2.2 after excluding North Little Rock, Memphis, Kenosha, and Galveston tourist lines.
The transit bus numbers are for all lines and systems nationwide; Chicago's heavily used system would have lower energy use per passenger. Conversely, the heavy rail numbers will be dominated by New York and Washington; Chicago's modestly used system will have somewhat higher energy use per passenger.
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While I think these numbers are important and instructive, I have an issue with measuring transit performance and efficiency with "passenger-miles" as it basically begs the land use question that impacts average trip lengths. Energy usage
per trip would be a better measure, I'd argue, and well-utilized transit systems would start to look much better given that (rapid rail and bus) transit trips are shorter than auto trips on average. Cars are indeed more efficient than transit for long trips, but that misses the point of an integrated transportation and land use strategic planning policy. The assumption that a single passenger-mile by car is equivalent to single passenger-mile by transit from the perspective of the rider and society introduces substantial bias to the metric that isn't clearly identified by the inclusion of comparable per-trip metrics.
Put another, more blunt way, passenger-mile stats tend to be the default tool of choice for the various anti-transit advocates, so I think it's necessary to point out these issues whenever they're brought up. Unfortunately, funding in this country tends to be largely apportioned to agencies based on the passenger-miles they provide, rather than trips, which is one component - in addition to local politics of course - of why CTA provides 80% of Chicagoland transit trips but receives around 55% of Chicagoland transit funding, and why CTA and it's short average trip lengths (relative to lower-density 'sunbelt' cities) is under constant budgetary pressure to maintain such high fare recovery ratios in support of a large highly utilized network.
If publicly-supported mass transit exists as a supplement and charity service filling in the gaps of a fixed development pattern and auto-oriented transportation network, then passenger-miles is a fine unit for performance measurement. But if transit is ever to be viewed as an essential public utility in coordinated support of a regional economy, the US will have to move to measuring based on total trips provided.