do mobility-based performance measures reflect emissions trends ?
DESCRIPTION
Do Mobility-Based Performance Measures Reflect Emissions Trends ?. Alex Bigazzi & Dr. Miguel Figliozzi ITE Western District Annual Meeting June 2012. Introduction. ?. Total Emissions. Congestion. Emissions Rates (per vehicle-mile). VMT. Research Questions. - PowerPoint PPT PresentationTRANSCRIPT
Do Mobility-Based Performance Measures Reflect Emissions Trends?
Congestion and Emissions Co-performance
Alex Bigazzi & Dr. Miguel Figliozzi
ITE Western District Annual MeetingJune 2012
1
Introduction
Congestion and Emissions Co-performance 2
Congestion
Emissions Rates
(per vehicle-mile)
Total Emissions
?
VMT
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?
3Congestion and Emissions Co-performance
Methodology
• Correlations between emissions estimates & transportation performance measures– Metropolitan level
• Cross-sections and trends
– Corridor level
4Congestion and Emissions Co-performance
5
Performance Measures
Congestion and Emissions Co-performance
• 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)
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
6Congestion and Emissions Co-performance
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
7Congestion and Emissions Co-performance
𝑒= 𝑓 (𝑣 ,𝑟 )
Results – Cross-section
Congestion and Emissions Co-performance 8
LA
NY
2010
9
Normalized to # travelers
Congestion and Emissions Co-performance
2010
10
Including total travel
Congestion and Emissions Co-performance
2010
11
Correlations
Congestion and Emissions Co-performance
Total Emissions
Emissions per
Traveler
VMT *
VHT *
Delay
VMT / traveler
VHT / traveler
Delay / traveler
Travel Time Index *
Commuter Stress Index *
Rush Hours per Day *
Roadway Congestion Index *
% Congestion (lane-miles)
% Congestion (VMT)
# Peak period travelers
No correlation< 0.2
Weak correlation0.2 – 0.5
Some correlation0.5 – 0.9
Strong correlation> 0.9
* Weak correlation for PM2.5 and HC
2010
12
Trends in Portland, OR
Congestion and Emissions Co-performance
1985 1990 1995 2000 2005 2010
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Year
Fra
ctio
n o
f 19
82
Va
lue
Peak Emissions per TravelerTTIPeak VHT per TravelerPeak VMT per TravelerPopulation
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
14Congestion and Emissions Co-performance
Conclusions
• 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 16
Mobility measures should not be associated with emissions
performance for a city
Future Work
• Arterial corridor study
• Vehicle class-separated performance
• Exposure performance measures
17Congestion and Emissions Co-performance
Thank you!
Congestion and Emissions Co-performance
QUESTIONS?
Alex Bigazzi: [email protected]
Miguel Figliozzi: [email protected]/~maf
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