Delay correction model for estimating bus emissions at signalized intersections based on vehicle specific power...

Area of Science:

• Environmental Science
• Transportation Engineering
• Traffic Management

Background:

• Intersections are major emission hotspots for buses, leading to high public exposure.
• Existing traffic performance indexes lack focus on their direct relationship with intersection emissions.
• Accurate emission estimation at intersections is crucial for urban air quality management.

Purpose of the Study:

• To propose a novel model that correlates bus emissions with traffic performance measures like delay time and number of stops at intersections.
• To develop a reliable method for adjusting emission factors based on intersection characteristics and traffic conditions.

Main Methods:

• Collected instantaneous emission and activity data using Portable Emission Measurement Systems (PEMS) to derive emission rates per vehicle specific power (VSP) bin.
• Utilized Global Position Systems (GPS) trajectory data from over 2000 diesel buses in Beijing to estimate delay and emission factors.
• Calculated delay correction factors for different intersection types (Arterial @ Arterial, Arterial @ Collector) and congestion levels.

Main Results:

• Established delay correction models tailored for specific intersection types and varying numbers of stops.
• Validated the model's reliability through comparative analysis of estimated versus field emission factors.
• Demonstrated that the proposed model accurately adjusts emission factors considering traffic delays.

Conclusions:

• The developed delay correction model provides a reliable approach to refine emission estimations at bus-heavy intersections.
• This research bridges the gap between traffic performance evaluation and emission assessment in urban transportation.
• Findings support improved traffic management strategies for reducing bus emissions and enhancing air quality in urban areas.