  Shared autonomous vehicles (SAVs) can have significant impacts on the
transport system and land use by replacing private vehicles. Sharing vehicles
without drivers is expected to reduce parking demand, and as a side effect,
increase congestion owing to the empty fleets made by SAVs picking up travelers
and relocating. Although the impact may not be uniform over a region of
interest owing to the heterogeneity of travel demand distribution and network
configuration, few studies have debated such impact at a local scale, such as
in transportation analysis zones (TAZs). To understand the impact in relation
to geographical situations, this study aims to estimate the impacts of SAVs at
the local scale by simulating their operation on a developed simulator. Using
the mainland of Okinawa, Japan as a case study, it was found that parking
demand was reduced the most in residence-dominant zones in terms of quantity
and in office-dominant zones in terms of proportion. As a side effect of
replacing private vehicles with SAVs, empty fleets increase congestion,
particularly at the periphery of the city. Overall, the results show the
heterogeneous impacts of the SAVs at the TAZ level on both land use and
traffic, thus suggesting the importance of developing appropriate strategies
for urban and transport planning when considering the characteristics of the
zones.
