The Secret Worldwide Transit Cabal

Informed but opinionated commentary and analysis on urban transportation topics from the Secret Worldwide Transit Cabal. Names have been omitted to protect the guilty.

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Monday, August 19, 2002

TRANSIT MODAL CHOICE IN JAPAN (Monorail Installment 11)

From the Cabalmaster:

This installment outlines how Japan has established a practical field of application for various
urban transport modes. The criteria are very well-defined (New Urban Transport Systems Reconsidered," by Akira Nehashi, Japan Railway & Transport Review No. 16, June 1998; see:, but defy simple description.

Japanese urban transport planning lacks the highly-politicized, adversarial atmosphere of American mode-choice "contests." Instead, the "domain of efficiency" for each mode has been worked out, based on technical and economic factors. It helps to remember that Japan must import virtually all of its oil and coal.

A technical fact often overlooked by U.S. politicians, and some planners: transportation "workload" depends on how many people travel -- and how far they travel.

It takes an extremely high passenger count to justify a short-distance fixed-guideway facility. A longer facility, which can carry longer trips, does not require such a high passenger count. This would be true from the standpoint of operating efficiency even if passenger revenue were not considered. In Japan, distance-based or "stage" fares are long-established and universally accepted.

For a given traffic level, a short-distance fixed-guideway facility has a higher operating cost per passenger-mile than than a long-distance one. It therefore requires a higher passenger volume to justify construction.

It's possible to imagine (or build) a fixed-guideway facility that cannot carry enough traffic to justify its construction. The best example, in the Japanese context at least, is "personal rapid transit."

Summarizing the Japanese criteria:

--Individual transportation, on foot or bicycle, is considered adequate for all trips shorter than 0.6 mile (1.0 kilometer), and for all trips along corridors where the one-way traffic density is less than 2,000 pass-mi per mile of route. Moving sidewalks might be provided in locations where traffic is great enough.

For example, no public transportation would be provided where the average trip length was one mile and the daily (two-way) traffic volume was less than 2,500 passengers (or, more correctly, boardings per route-mile) per day.

Buses, as emphasized in Japanese transport literature, provide no economies of scale. Given a one-mile average trip length, buses are economical for traffic volumes up to 5,000 daily boardings per route-mile.

At higher volumes, bus operation becomes uneconomical (no economies of scale!), but the minimum threshold for conventional urban railways is 12,500 boardings per route-mile per day, given a one-mile average trip length.

These "thresholds" change drastically as average trip length changes -- again, owing to economies of scale!

[One critical fact that is almost never considered in the U.S.: if average trip length increases, more vehicle-miles must be operated, even if "ridership" (boardings per route-mile) does not change. If not, average vehicle occupancy will increase (more passenger-miles per route-mile), and by implication peak-hour crowding will also increase.]

Given a 5-mile average trip length, public transport becomes viable with fewer than 500 boardings per route-mile per day. Buses become uneconomic with more than 750 boardings per route-mile per day, but conventional railways are not justified with fewer than 2,000 boardings per route-mile per day. The standard Japanese transit bus is about 35 feet long, eight feet wide and seats 28 passengers. The legal "maximum load" is 74 passengers, or 6.9 passengers per meter of vehicle length. Articulated buses are not used for urban transport services in Japan.

Under the Japanese criteria, if public transportation is justified at all, and the average trip length ranges from 6 miles (with 700 daily boardings per route-mile) to 31 miles (with 130 daily boardings per route-mile), it is better to build a railway than operate buses.

Skeptics are reminded that 1) these criteria were developed with reference to Japanese economic conditions, and 2) buses provide no economy of scale. Longer trips require more vehicle-miles per passenger, and so the "economy of scale" effect reduces the boarding "threshold" as average trip length increases.

Express ("highway") buses are efficient only for longer trips, and once the daily boarding count exceeds 200 per route-mile, high-speed rail becomes more efficient.

It is essential to keep these numbers in context. A suburban rail line handling an average travel distance of 31 miles would be longer than 31 miles end-to-end. The minimum daily "boarding count" required to justify a 50-mile suburban rail line becomes 6,500. Converting from "average daily" to "average weekday" ridership in line with U.S. practice, this implies more than 8,000 boardings per weekday.

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