Home
hamburger menu icon

Mass Transit

Mass transit requires sufficient population density to be financially viable; otherwise, it doesn't tend to help cities much. See also our analysis of energy used in mass transit.

Density and Transit Viability

Mass transit, such as municipal buses and light rail, is financially infeasible below certain density thresholds. Following are some estimates of those thresholds.

The image: "density_threshold.svg" cannot be found!

Population density of select develoments are included for comparison. For some transit stops, residential density can be substituted with job density. Sources: 1, 2, 3, 4, 5, 6, 7. See also our analysis of the density of different housing forms.

Several other factors influence the viability of transit, including the degree to which different kinds of uses are mixed 8 and transit construction costs 9.

Assessing Light Rail Effectiveness (PDF)

As a case study, we examined a proposed light rail system in Nashville. Light rail can be a highly effective solution in dense cities, but requires a high throughput to be successful. A light rail system with relatively few potential passengers per mile of line is not likely to be well used, as would likely be the case for the recently proposed light rail project in Nashville 10.

The image: "Residents per Mile Light Rail.svg" cannot be found!

The energy efficiency of a light rail system, as measured by passenger-miles per unit energy, can also vary widely, depending on how well-used a system is 10.

Light Rail City Systems - Facts and Figures (2016)
CityUrban Area PopulationMiles of Light RailPassenger Miles Per Gallon of Diesel
Buffalo935,9066.456.89
Nashville969,58728.4NO DATA
Salt Lake City1,021,24344.879.67
Charlotte1,249,4429.6103.72
Hampton1,439,6667.453.65
San Jose1,664,49642.293.62
Sacremento1,723,63442.975.65
Pittsburgh1,733,85326.238.15
Cleveland1,780,6731836.25
Portland1,849,89860149.65
St. Louis2,150,70646138.88
Baltimore2,203,6633060.97
Denver2,374,20358.5124.36
Minneapolis2,650,8901290.4
San Diego2,956,74653.5176.55
Seattle3,059,39321.95242.44
San Francisco3,281,21236.897.58
Phoenix3,629,11426.3197.01
Boston4,181,01923104.23
Houston4,944,33223.885.99
Dallas5,121,8929377.51
Los Angeles12,150,996105123.47
Newark18,351,2956.293.14

Public Transit Systems perform best with high ridership, which has been a challenge throughout the U.S. across all public transit modes. While there is no way of knowing how systems will perform in the future, population size and system scale can be used to as a crude indicator of passenger throughput. The chart to the left shows that Nashville would be the second smallest urbanized area (as defined by the National Transit Database) with a Light Rail System in the U.S., and that larger populations tend to operate with greater efficiency. Source: National Transit Database (2016) -’Fuel and Energy’ and ‘Metrics’ data listings available at (https://www.transit.dot.gov/ntd/ntd-data) as of February 3rd, 2018 Notes: Light Rail mileage drawn from publicly available sources for each transit system reported. *This exhibit was prepared for a proposed Nashville Light Rail in April 2018.


References

  1. Bradford, C. "The Census Bureau embraces weighted density". Smart Cities Dive. Accessed May 8, 2021. ↩

  2. Guerra, E., Cervero, R. "Transit and the “D” Word". Access Magazine 40. Spring 2012. ↩

  3. Holtzclaw, J. "Using Residential Patterns and Transit to Decrease Auto Dependence and Costs". San Francisco, CA: Natural Resources Defense Council. June 1994. ↩

  4. Pushkarev, B., Zupan, J. "Where Transit Works: Urban Densities for Public Transportation". in Urban Transportation: Perspectives and Prospects, ed. by H. S. Levinson and R. A. Weant, Eno Foundation. 1982. ↩

  5. Santasieri, C. "Planning for Transit-Supportive Development: A Practitioner’s Guide". Federal Transit Administration, U. S. Department of Transportation. June 2014. ↩

  6. The Kinder Institute for Urban Research. "Excerpt: Many Cities Have Transit. How Many Have Good Transit?". Rice University. November 2018. ↩

  7. Twin Cities Metropolitan Council. "Density & Activity Near Transit: Local Planning Handbook". January 2018. ↩

  8. Cooke, S., Behrens, R. "Correlation or cause? The limitations of population density as an indicator for public transport viability in the context of a rapidly growing developing city". Transportation Research Procedia 25, pp. 3003-3016. 2017. ↩

  9. Transit Costs Project. "About". Accessed May 8, 2021. ↩

  10. Federal Transit Administration. "National Transit Database". Accessed May 24, 2019. ↩ ↩2