Roadway Congestion’s Effects on Motor Vehicle Emissions Congestion Effects on Emissions A Review...

Congestion Effects on Emissions

Roadway Congestion’s Effects on Motor Vehicle Emissions

A Review of Methods & Findings

-Alex Bigazzi24 Feb 2010

Outline

• Introduction• Defining Congestion• Review of Methods• Summary of Findings• Conclusions (Research Needs)


Introduction

Congestion Effects on EmissionsIntroductionDefining Congestion

MethodsFindings

ConclusionsReferences

• Congestion and Emissions Increasing [1-3]

• Congestion Increases Emissions??? (i.e., CMAQ) [4-6]

• Costs and mitigation strategies

Congestion

• Longer travel times• Unreliable travel times• Accelerations• Rerouting• Suppressed Demand• Departure time changes• Mode shift• Vehicle wear• Vehicle costs• Freight operation changes

Emissions?

Introduction (Con’t)


• Objectives1. Review methods to study effects2. Summarize state of knowledge3. Identify research needs

• Scope of Review–Major studies – Key papers covering primary effects– Not: air quality, mitigation, indirect

emissions, or non-emissions studies

IntroductionDefining Congestion

MethodsFindings


Defining Roadway Congestion


MethodsFindings

• Recurrent vs Non-recurrent [8-10]

Traveldemand>supply

Sub-optimal system performance

Roadway conditions in which vehicle operation is affected by other road users

[4,7]


Review of Methods


MethodsFindings

• Important features [11-13]

1. Travel2. Speed profile3. Fleet

• Defining ‘uncongested’ [3,7,14]

– Free-flow speeds? (Measured or design?)– Steady-state?– Fixed demand or supply?– Optimal?


Methods (Con’t)


MethodsFindings

• Empirical – direct measurement [15-18]

– Real conditions– Ltd coverage– Ltd experimental control

• Modeling [12,19-27]

– High uncertainty– Travel demand/traffic model limits– Difficult on multiple levels (macro/micro)


Summary of Findings


MethodsFindings

Roadway Congestion Effects

Impacts on Motor Vehicle Emissions

Decreased average travel speed

at very low speeds [14,17,28,29,32]

for moderate speed reductions [16,28-31]

Increased speed variability (accel)

with accel intensity and frequency [14,28,29,33,34]

impact varies with travel speed [29,33,35]

Travel time unreliability

no studies found on direct or indirect effects

Suppressed demand Under most scenarios [4,7,24,25]

Depends on network factors [21,26,36]

Undifferentiated, short-term effects

by local AQ msrmt [15,17,37]

?


Findings (Con’t)


MethodsFindings

Not well studied/quantified:

• Travel time unreliability• Rerouting [36]

• Departure time changes• Mode shift to transit [32]

• Vehicle wear• Vehicle operating costs• Freight responses• Resuspension of PM10


Conclusions – Methods and Findings


MethodsFindings

• No method captures all effects– Arbitrary ‘uncongested’ conditions

• We cannot conclude that congestion increases emissions– Depends what is exogenous– Balance varies with location


Conclusions – Research Needs


MethodsFindings

• Benchmarks & multi-level modeling• Micro/macro diff b/n recurrent/nonrecurrent– Drive patterns (under diff conditions)

– Driving elasticity to TT reliability• Eco-driving without induced demand• Indirect effects

(routing, mode, freight, vehicle wear, resuspension)

• Relations among exhaust gasses• Effects of diff fleet scenarios


References 1


MethodsFindings

1. J. Fenger, “Urban air quality,” Atmospheric Environment, vol. 33, 1999, pp. 4877–4900. 2. U. S. Environmental Protection Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-

2007, U.S. EPA, 2009.3. D. Schrank and T. Lomax, “The 2007 urban mobility report,” Texas Transportation Institute, College

Station, TX, 2007. 4. P.R. Stopher, “Reducing road congestion: a reality check,” Transport Policy, vol. 11, 2004, pp. 117–131.5. O. Johansson, “Optimal road-pricing: simultaneous treatment of time losses, increased fuel

consumption, and emissions,” Transportation Research Part D, vol. 2, 1997, pp. 77–87. 6. Transportation Research Board, The Congestion Mitigation and Air Quality Improvement Program:

Assessing 10 Years of Experience, 2002. 7. European Conference of Ministers of Transport (ECMT), Managing Urban Traffic Congestion, OECD,

Transport Research Center, 2007. 8. J. Kwon, M. Mauch, and P. Varaiya, “Components of Congestion: Delay from Incidents, Special Events,

Lane Closures, Weather, Potential Ramp Metering Gain, and Excess Demand,” Transportation Research Record: Journal of the Transportation Research Board, vol. 1959, 2006, pp. 84–91.

9. A. Skabardonis, P. Varaiya, and K.F. Petty, “Measuring recurrent and nonrecurrent traffic congestion,” Transportation Research Record: Journal of the Transportation Research Board, vol. 1856, 2003, pp. 118–124.

10. M.E. Hallenbeck, J. Ishimaru, and J. Nee, “Measurement of recurring versus non-recurring congestion,” Washington State Transportation Center (TRAC), 2003.

11. S. Pandian, S. Gokhale, and A.K. Ghoshal, “Evaluating effects of traffic and vehicle characteristics on vehicular emissions near traffic intersections,” Transportation Research Part D, vol. 14, 2009, pp. 180–196.


References 2


MethodsFindings

12. J. Kuhlwein and R. Friedrich, “Uncertainties of modelling emissions from road transport,” Atmospheric Environment, vol. 34, 2000, pp. 4603–4610.

13. J. Kuhlwein and R. Friedrich, “Traffic measurements and high-performance modelling of motorway emission rates,” Atmospheric Environment, vol. 39, 2005, pp. 5722–5736.

14. I.D. Greenwood, R.C.M. Dunn, and R.R. Raine, “Estimating the effects of traffic congestion on fuel consumption and vehicle emissions based on acceleration noise,” Journal of Transportation Engineering, vol. 133, 2007, p. 96.

15. J.W.D. Boddy, R.J. Smalley, N.S. Dixon, J.E. Tate, and A.S. Tomlin, “The spatial variability in concentrations of a traffic-related pollutant in two street canyons in York, UK—Part I: the influence of background winds,” Atmospheric Environment, vol. 39, 2005, pp. 3147–3161.

16. M.B. Dijkema, S.C. van der Zee, B. Brunekreef, and R.T. van Strien, “Air quality effects of an urban highway speed limit reduction,” Atmospheric Environment, vol. 42, Dec. 2008, pp. 9098-9105.

17. M. Kohler, U. Corsmeier, U. Vogt, and B. Vogel, “Estimation of gaseous real-world traffic emissions downstream a motorway,” Atmospheric Environment, vol. 39, 2005, pp. 5665–5684.

18. K. Ropkins, J. Beebe, H. Li, B. Daham, J. Tate, M. Bell, and G. Andrews, “Real-World Vehicle Exhaust Emissions Monitoring: Review and Critical Discussion,” Critical Reviews in Environmental Science and Technology, vol. 39, 2009, pp. 79–152.

19. H.C. Frey and J. Zheng, “Probabilistic analysis of driving cycle-based highway vehicle emission factors,” Environ. Sci. Technol, vol. 36, 2002, pp. 5184–5191.

20. R. Joumard, F. Philippe, and R. Vidon, “Reliability of the current models of instantaneous pollutant emissions,” Science of the Total Environment, The, vol. 235, 1999, pp. 133–142.

21. R.G. Dowling, Predicting air quality effects of traffic-flow improvements: final report and user's guide, Transportation Research Board National Research, 2005.


References 3


MethodsFindings

22. K. Adler, M. Grant, and W. Schroeer, “Emissions Reduction Potential of the Congestion Mitigation and Air Quality Improvement Program: A Preliminary Assessment,” Transportation Research Record: Journal of the Transportation Research Board, vol. 1641, 1998, pp. 81–88.

23. K. Hirschmann and M. Fellendorf, “A toolbox to quantify emission reductions due to signal control,” 89th Annual Meeting of the Transportation Research Board, Washington, D.C.: 2010.

24. R.B. Noland and M.A. Quddus, “Flow improvements and vehicle emissions: Effects of trip generation and emission control technology,” Transportation Research Part D, vol. 11, 2006, pp. 1–14.

25. F.G. Stathopoulos and R.B. Noland, “Induced travel and emissions from traffic flow improvement projects,” Transportation Research Record: Journal of the Transportation Research Board, vol. 1842, 2003, pp. 57–63.

26. HDR, Assessing the Full Costs of Congestion on Surface Transportation Systems and Reducing Them through Pricing, U.S. DOT, 2009.

27. R. Smit, A.L. Brown, and Y.C. Chan, “Do air pollution emissions and fuel consumption models for roadways include the effects of congestion in the roadway traffic flow?,” Environmental Modelling and Software, vol. 23, 2008, pp. 1262–1270.

28. M. Barth and K. Boriboonsomsin, “Real-World Carbon Dioxide Impacts of Traffic Congestion,” Transportation Research Record: Journal of the Transportation Research Board, vol. 2058, 2008, pp. 163–171.

29. M. Barth, G. Scora, and T. Younglove, “Estimating emissions and fuel consumption for different levels of freeway congestion,” Transportation Research Record: Journal of the Transportation Research Board, vol. 1664, 1999, pp. 47–57.

30. E. Cascetta, V. Punzo, and R. Sorvillo, “Impact on vehicle speeds and pollutant emissions of a fully automated section speed control scheme on the Naples urban motorway,” 89th Annual Meeting of the Transportation Research Board, Washington, D.C.: 2010.


References 4


MethodsFindings

31. S.K. Zegeye, B. De Schutter, H. Hellendoorn, and E. Breunesse, “Reduction of Travel Times and Traffic Emissions Using Model Predictive Control,” American Control Conference, 2009.

32. S.D. Beevers and D.C. Carslaw, “The impact of congestion charging on vehicle emissions in London,” Atmospheric Environment, vol. 39, 2005, pp. 1–5.

33. M. Barth and K. Boriboonsomsin, “Energy and emissions impacts of a freeway-based dynamic eco-driving system,” Transportation Research Part D: Transport and Environment, vol. 14, Aug. 2009, pp. 400-410.

34. K. Boriboonsomsin and M. Barth, “Impacts of freeway high-occupancy vehicle lane configuration on vehicle emissions,” Transportation Research Part D: Transport and Environment, vol. 13, Mar. 2008, pp. 112-125.

35. K. Boriboonsomsin and M. Barth, “Evaluating Air Quality Benefits of Freeway High-Occupancy Vehicle Lanes in Southern California,” Transportation Research Record: Journal of the Transportation Research Board, vol. 2011, Jan. 2007, pp. 137-147.

36. A. Nagurney, “Congested urban transportation networks and emission paradoxes,” Transportation Research Part D: Transport and Environment, vol. 5, Mar. 2000, pp. 145-151.

37. S. Mahendra, “Air Quality Deterioration Due to Traffic,” 89th Annual Meeting of the Transportation Research Board, Washington, D.C.: 2010.


Thank you!


Questions????

Alex Bigazzi: [email protected]

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