Emissions impact of connected and automated vehicle deployment in California - model results

This study helps understand how the anticipated emergence of autonomous
vehicles will affect various aspects of society and transportation,
including travel demand, vehicle miles traveled, energy consumption, and
emissions of greenhouse gases and other pollutants. The study begins with
a literature review on connected and automated vehicle (CAV) technology
for light-duty vehicles, the factors likely to affect CAV adoption,
expected impacts of CAVs, and approaches to modeling these impacts. The
study then uses a set of modifications in the California Statewide Travel
Demand Model (CSTDM) to simulate the following scenarios for the
deployment of passenger light-duty CAVs in California by 2050: (0)
Baseline (no automation); (1) Private CAV; (2) Private CAV + Pricing; (3)
Private CAV + Zero emission vehicles (ZEV); (4) Shared CAV; (5) Shared CAV
+ Pricing; (6) Shared CAV + ZEV. The modified CSTDM is used to forecast
travel demand and mode share for each scenario, and this output is used in
combination with the emission factors from the EMission FACtor model
(EMFAC) and Vision model to calculate energy consumption and criteria
pollutant emissions. The modeling results indicate that the mode shares of
public transit and in-state air travel will likely sharply decrease, while
total vehicle miles traveled and emissions will likely increase, due to
the relative convenience of CAVs. The study also reveals limitations in
models like the CSTDM that primarily use sociodemographic factors and
job/residence location as inputs for the simulation of activity
participation and tour patterns, without accounting for some of the
disruptive effects of CAVs. The study results also show that total vehicle
miles traveled and vehicle hours traveled could be substantially impacted
by a modification in future auto travel costs. This means that the
eventual implementation of pricing strategies and congestion pricing
policies, together with policies that support the deployment of shared and
electric CAVs, could help curb tailpipe pollutant emissions in future
scenarios, though they may not be able to completely offset the increases
in travel demand and road congestion that might result from CAV
deployment. Such policies should be considered to counteract and mitigate
some of the undesirable impacts of CAVs on society and on the environment.