How Do Traffic Control Measures Affect Vehicle Gas Emissions

1. How Do Traffic Control Measures Affect Vehicle Gas Emissions Presented by: Ryan O’Connell Co-Authors: Kevin Lu Dr. Wen Cheng Dr. Xudong Jia

2. Overview • Introduction • Objective • Methodology • Study Location • Data Analysis • Conclusions and Recommendations

3. Introduction • To ensure a safe and efficient traffic movement on the systems of roadways, a large multitude of congestion relief measures have been proposed and developed over the last century • However, most of the available methods are based solely on operational standards and rarely consider the potential impacts on emissions

4. Objective • To fill the gap and help researchers further understand the impacts of various traffic congestion relief measures on vehicle emissions, the main objective of this study is to explore the relationship between gas emissions and some of the most frequently used traffic control measures or devices. • Specifically, the traffic control measures investigated in the study includes stop control, yield control, pre-timed traffic signal, actuated traffic signal and signal coordination.

5. Methodology • Emissions analyzed: • Carbon monoxide (CO) • A product of incomplete combustion and occurs when carbon in the fuel is partially oxidized. Reduces the flow of oxygen in the bloodstream and is particularly dangerous to persons with heart disease. • Nitrogen oxides (NOx) • Under the high pressure and temperature conditions in an engine, nitrogen and oxygen atoms in the air react to form various nitrogen oxides. Nitrogen oxides are precursors to the formation of ozone. • Volatile organic compounds (VOC) • Are emitted both from the tailpipe and through fuel evaporation.

6. Methodology • Control types analyzed: • Yield • Stop • Free

7. Methodology • The following procedure was implemented for Synchro analysis of the study area: • Create the traffic network in Synchro based on data observed on Google Maps. • Assign the different traffic control types to all intersection approaches, e.g.: yield control, stop control, and free control. • Input traffic volume data (100, 500, or 1000 vehicles per hour for through lanes and 10, 50, or 100 vph, respectively, for turn lanes) at all the intersections. • Run the simulation for all possible combinations of traffic control measures and traffic volumes. Create reports of simulation outputs containing CO emission, NOx emission, and VOC emission. • Analyze the outputs in the form of charts to quantify the relationship between gas emissions and various traffic control measures.

8. Methodology • Fuel consumption formula (gallons): • F = TT*d = k1 -TD* k2 +ST* k3 • Emissions formulas (grams): • CO = F*69.9 g/gal • NOx = F*13.6 g/gal • VOC = F*16.2 g/gal Where k1 = 0.075283 – 0.0015892 * S+ 0.000015066 * S2 k2 = 0.7329 k3 = 0.0000061411 * S2 F = fuel consumption in gallons S = cruise speed in mph TT = vehicle miles traveled TD = total delay in hours ST = total stops in vehicles per hour

9. Study Location Fresno, California

10. Data Analysis

11. Data Analysis

12. Data Analysis

13. Conclusion • Greenhouse gas emissions from vehicles consist mostly of carbon monoxide. • Volatile organic compound emissions are slightly higher than nitrogen oxide emissions. • Emissions are proportional to assumed traffic volume. • Intersections with no traffic control produce much higher greenhouse gas emissions than those with yield control and stop control, which indicates that the fuel consumption formula may not be valid for no-control intersections. • Intersections with stop control produce slightly higher greenhouse gas emissions than those with yield control.

14. Recommendations • If necessary, free control would be best implemented and/or maintained at intersections with the least amount of existing traffic volume in order to minimize emissions • For intersections with higher existing traffic volumes either stop control or yield control would be appropriate

15. The End Any Questions?