Curbing Zombie Cars: Implementing a VMT Tax on Zero-Occupant AVs to Discourage Unnecessary Trips

Abstract

Like many American cities, Atlanta experienced an infrastructure boom in the post-war years that resulted in a network of highways and interstates encouraging an automobile-dependent lifestyle for its residents. With no natural boundaries, Atlanta’s growth sprawled outward creating suburbs in all directions. Today, Atlanta is home to 4.5 million residents whose primary mode of transportation is the car. The resulting congestion across the metro region costs $1,130 per commuter per year (1) and congestion remains high on the list of resident’s complaints (2). While the advent of automated vehicles (“AVs”) is poised to usher in an era of unprecedented road safety among other benefits, it is likely that the technology will lead to unexpected changes in the urban fabric of the city, similarly to the way cars reshaped Atlanta a century ago. One particularly harmful potential consequence of AVs is the likelihood that private owners will begin to increase the number of trips their vehicles make, because now the vehicle can make trips unsupervised by human drivers. Many owners will value the ability to send a vehicle home unsupervised in order to avoid paying for increasingly expensive parking in the city, but this behavior potentially doubles the amount of vehicle-miles traveled (“VMT”) accrued. Any increase in VMT is undesirable, but a sharp uptick in peak hour VMT in Atlanta would be gridlock inducing. AVs are not yet commercially available, so lawmakers have the rare opportunity to take steps to prevent this undesirable behavior before it begins, rather than having to retroactively alter behavior after it has become commonplace. One pre-emptive solution to mitigating unnecessary VMT is to charge empty AVs (“zombie cars”) a tax for each mile they drive. If the tax is set high enough, it could deter owners from sending their cars on unnecessary trips, choosing to park instead of accruing additional VMT. This report sets out the formula that jurisdictions should use to set the rates for owners of internal-combustion engine AVs (“ICE AVs”) and owners of electric AVs (“EAVs”) and applies these rates to the Atlanta metro area. Upon analysis, the rate should be set to at least $0.14 per mile for ICE AVs and to $0.23 per mile for EAVs in the Atlanta area.