Methodology for Developing Transit Bus Speed-Acceleration Matrices for Load-Based Mobile Source Emissions Models

Abstract

An emissions model for transit bus based on road load estimates emissions as a function of transit bus power demand for given transit bus activities and environmental conditions. Transit bus speed and acceleration rates are key activity parameters and are the most important parameters in the estimation of transit bus power demand, also known as engine load. Once the transit bus engine load is calculated for a given speed and acceleration, emissions in grams per vehicle hour can be calculated with grams per brake-horsepower hour emission rates. However, collecting speed and acceleration data on various road types and times of day requires extensive efforts for use in load-based mobile source emissions models. To quantify Atlanta regional transit bus speed and acceleration rates, the Georgia Institute of Technology research team installed trip data in a transit bus operated by the Metropolitan Atlanta Rapid Transit Authority. The team collected second-by-second speed and location data for 3 weeks on a varie...