Do Mobility-Based Performance Measures Reflect Emissions Trends ?

1. Do Mobility-Based Performance Measures Reflect Emissions Trends? Congestion and Emissions Co-performance Alex Bigazzi & Dr. Miguel Figliozzi ITE Western District Annual Meeting June 2012

2. Introduction ? Total Emissions Congestion Emissions Rates (per vehicle-mile) VMT Congestion and Emissions Co-performance

3. Research Questions Do congestion & mobility performance measures reflect macroscopic emissions trends? If not, what transportation performance measures can be used to better understand and indicate emissions trends? Congestion and Emissions Co-performance

4. Methodology • Correlations between emissions estimates & transportation performance measures • Metropolitan level • Cross-sections and trends • Corridor level Congestion and Emissions Co-performance

5. Performance Measures • Average speeds* • Travel Time Index, Commuter Stress Index • Reliability of speeds* • - Buffer Time Index, Planning Time Index • Congestion extent • - % congested, # rush hours, Roadway Cong. Index • Amount of travel • - VMT, VHT * Normalized to travel volume (i.e. only sensitive to changes in speed) Congestion and Emissions Co-performance

6. Traffic Data • Metropolitan-level Estimates • 2011 Urban Mobility Report data tables • 101 U.S. Urban Areas • Peak-period speeds, volumes, # travelers, congestion performance… • Simplifying assumptions • Corridor Estimates • Hourly freeway data • 3 years of counts & speeds over 14 miles Congestion and Emissions Co-performance

7. Emissions Estimates MOVES emissions model (U.S. EPA) Emissions rates a function of speed and facility only (not fleet or time) CO2e, CO, NOx,PM2.5,HC Congestion and Emissions Co-performance

8. Results – Cross-section 2010 LA NY Congestion and Emissions Co-performance

9. Normalized to # travelers 2010 Congestion and Emissions Co-performance

10. Including total travel 2010 Congestion and Emissions Co-performance

11. Correlations 2010 Strong correlation> 0.9 Some correlation0.5 – 0.9 Weak correlation0.2 – 0.5 No correlation< 0.2 * Weak correlation for PM2.5 and HC Congestion and Emissions Co-performance

12. Trends in Portland, OR Congestion and Emissions Co-performance

13. Corridor Study Similar analysis on a 14mi freeway over 3 years Strong correlations between Emissions and VMT, VHT Weak correlations with speed, congestion, and reliability Congestion and Emissions Co-performance

14. Conclusions Mobility measures should not be associated with emissions performance for a city Mobility and related congestion performance measures do not reflect emissions trends at the aggregate level VMT and VHT are the key outputs of the transportation system to understand emissions trends Congestion and Emissions Co-performance

15. Future Work Arterial corridor study Vehicle class-separated performance Exposure performance measures Congestion and Emissions Co-performance

16. Thank you! Congestion and Emissions Co-performance Questions? Alex Bigazzi: abigazzi@pdx.edu civil.alexbigazzi.com Miguel Figliozzi: figliozzi@pdx.edu web.cecs.pdx.edu/~maf