Identifying Roadway Physical Characteristics that Contribute to Emissions Differences between Hybrid and Conventional Vehicles

In this study, a second-by-second (SbS) data set obtained from
monitoring vehicle emissions over a series of 75 test runs from 2 test
vehicles (a conventional vehicle (CV) and a hybrid-electric vehicle (HEV))
over an 18-month period in 2010-2011 during real-world on-road operations
on a specified 32-mile route in Chittenden County, Vermont was used in an
innovative new method of analysis to assess emissions differences between
the two propulsion systems and attribute these differences to physical
roadway/infrastructure characteristics. The K-S test was used to assess
the difference between the cumulative distributions of the CV and HEV
emissions samples on each link, and the K-S test statistic was regressed
against the full set of roadway link characteristics. The regression
results allowed the team to identify specific roadway characteristics that
contribute to emissions differences between the vehicle types. Overall,
the models that included maximum grade and intersection control type
performed best, however speed limit and horizontal curvature were also
shown to be important. The performance differences identified in this
project confirm that engine controls that are responsive to roadway
characteristics are necessary.