An Integrated Field Study of Turbulence and Dispersion Variations in Road Microenvironments.

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Transportation Engineering

Background:

• Traffic-related air pollutants (TRAPs) pose exposure risks due to dispersion from vehicle emissions.
• Accurate identification of TRAP emission hotspots is crucial for risk assessment.

Purpose of the Study:

• To investigate the relationship between turbulent kinetic energy (TKE) and pollutant dispersion (D).
• To develop a field-validated TKE-D model for estimating vehicle emissions and identifying hotspots.

Main Methods:

• Conducted a five-year near-road sampling campaign and an on-road sampling campaign.
• Measured TKE and calculated pollutant dispersion (D) based on vehicle emissions and concentrations.
• Collected 198 near-road and 377 on-road measurement pairs for analysis.

Main Results:

• A positive relationship was observed between TKE and D with vehicle flow rate near roads (R² ≥ 0.69).
• On-road measurements showed similar decay patterns and vehicle type sensitivity for TKE and D.
• Developed a robust TKE-D relationship with strong correlation (R² ≥ 0.61) and consistent slopes (1.1-1.3).

Conclusions:

• Field evidence confirms a positive association between TKE and D, independent of measurement methods or location.
• The TKE-D relationship allows for vehicle emission estimation using TKE as the sole input.
• Facilitates high spatiotemporal resolution identification of traffic emission hotspots.