Tolling and Pricing Program - Links to Tolling and Pricing Program Home

Appendix B. Summary of Study Project Reported Environmental Findings




Major Caveats/Limitations

Simulated Pricing Field Demonstrations

Oregon Mileage Fee Concept and Road User Fee Pilot Program

No Environmental Analysis Performed

Puget Sound Traffic Choices Study

No Environmental Analysis Performed

Commute Atlanta Mileage Based Value Pricing

No Environmental Analysis Performed

Before-After Project Evaluations – U.S.

Minnesota I-394 MnPASS HOT Lanes

  • Small increases and decreases in on-hour average CO levels, ranging from +0.29 to -.01 parts per million
  • HOT lanes had no substantial impact on air quality
  • None reported
  • Small project-related increases in noise levels found at three sites
  • HOT lanes had no statistically significant change in average neighborhood sound levels
  • None reported
  • Beneficiaries of the HOT lane included a diverse population across all income, age, race/ethnicity, employment, and mode usage groups
  • No significant correlation between socio-demographics and project benefits and attitudes 
  • None reported

San Diego I-5 HOT Lanes

  • Estimated a.m. peak emissions on the control corridor increased three to five times more than emissions on the project corridor
  • The HOT lanes moderated emission levels in the project corridor
  • Since the impact of exogenous factors could not be precisely controlled or measured, all observed differences between the control and project corridors could not be attributed to the project.
  • On the study roadway, emissions increased significantly more on the HOT lanes than on the general purpose lanes
  • Consistent with the traffic data showing increased use of the HOT lanes

Empty cell.

Before-After Project Evaluations – International

The Stockholm Trial

  • 8.5 -14% decrease in emissions depending on the pollutant
  • The project had a positive impact on emissions
  • Weather conditions thought to contribute to emissions reductions to some degree
  • Minor reduction in noise levels
  • The project did not significantly impact noise levels
  • None reported
  • Great variation in congestion charges paid by individual
  • Wealthy, inner-city men pay the most
  • Higher income earners pay more than lower income earners
  • Commercial traffic and business trips are “net winners”
  • How pricing revenues are redistributed is the key to total cost-benefit effects on different people
  • None reported

London Congestion Pricing

  • Emissions decreased by between 13 and 16% depending on the pollutant, for the original project
  • Emissions decreased by between 2 and 6%, depending on the pollutant, for the Western Extension
  • The project had a positive impact on air quality
  • Roadside monitoring results inconclusive (unable to differentiate project impacts from exogenous factors)
  • Calculated emissions did estimate project impacts
  • No significant, project-attributable changes in noise levels
  • The project did not impact perceptible noise levels
  • Roadside monitoring results inconclusive (unable to differentiate project impacts from exogenous factors)
  • Significant reductions in traffic volumes are necessary to reduce noise levels (to get the smallest discernable change in noise levels—3 dBA—traffic volumes must be cut in half)
  • Actual impacts were less than travelers themselves expected
  • Issues of greatest concern are not project related
  • Majority of respondents found the charge affordable
  • No significant adverse and disproportionate impacts on environmental justice populations
  • Despite best efforts, some groups are likely over or under-represented in data collection
  • Perception and attitude data are not as “scientific” as quantitative data

Singapore Area Pricing

  • CO reductions in a.m. peak, monthly average NOx reductions, and redeuced smoke and haze (immediately after first project)
  • Project had a positive impact on air quality
  • Declines in smoke and haze could not be fully attributed to the project
  • Some people did not benefit from the initial project, e.g., those for whom the cost of the charge is not off-set by reduced travel time
  • After some initial crowding, transit riders enjoyed better service as service was expanded over time
  • Middle income travelers felt adversely effected
  • Shifts to transit were uniform across income groups
  • Although not all people benefitted equally, overall, the project did not significantly and disproportionately impact lower income people
  • None reported


Office of Operations