Accounting for acceleration and deceleration emissions in intersection dispersion modeling using MOVES and CAL3QHC

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Transportation Engineering

Background:

• Traditional near-road dispersion modeling uses simplified vehicle behavior (idle/cruise).
• The MOVES model enables second-by-second emission factors based on modal activity (acceleration, deceleration, idle, cruise).

Purpose of the Study:

• To investigate the impact of incorporating modal emissions data into near-road dispersion modeling.
• To determine optimal methods for representing acceleration and deceleration in dispersion models.

Main Methods:

• Utilized MOVES emission factors for vehicular modal activities.
• Adapted CAL3QHC input files to include unique modal links.
• Examined dividing acceleration/deceleration segments into multiple sublinks for higher resolution.

Main Results:

• The proposed method significantly increases CO prediction precision at intersections (up to 400% higher than cruise-and-idle).
• Acceleration emission factors are substantially larger than cruise emission factors.
• The number of sublinks used impacts predicted concentrations, with potential for erratic EFs from MOVES with excessive subdivision.

Conclusions:

• Incorporating modal vehicle activity improves the precision of near-road dispersion modeling.
• A method of dividing links by speed change increments is proposed for better representation of acceleration/deceleration.
• Further research is needed to validate accuracy with real-world monitored data.