Autonomous Vehicles: A New Solution to the Last Mile Problem?
The problem of limited accessibility to public transit is a well-documented problem in transportation theory and network literature. The lack of first and last mile specific transit services impairs access to public transit causing more commuters to opt for private modes of transportation over public modes of transit. The emergence of autonomous vehicles (AVs) may provide an opportunity to conveniently connect individuals to transit nodes and thereby increase load factors (passengers/vehicle) of existing transit services and improve their system operating efficiency (on a passenger-mile/passenger-kilometer basis).
A case study was developed to evaluate the potential of autonomous vehicles (i. e. self-driving vehicles) to provide last mile services for trips from Detroit Metro Airport to Ann Arbor, Michigan. The life cycle energy and greenhouse gas results from utilizing single trip “door to door” transport from the airport to the final destination (e. g. passenger vehicles, taxis, shuttles) are compared to public transit coupled with an AV trip segment between the transit hub and the final destination. Multiple scenarios are explored to evaluate the life cycle energy, emissions and costs. Last mile segments served by AVs coupled with trains or buses show significant energy and emission benefits compared to “door to door” options using sedans and van shuttles. AVs could facilitate accessibility to public transit nodes and consequently increase use of more efficient, public transit “door to door” options. Results indicate life cycle energy savings between 50 and 60% for the AV-public transit option when compared to the taxi option. Travel time differences were also estimated for each travel option scenario. The results also highlight hot spots to be addressed through AV system design to make AV services attractive to users.