  Ridesplitting -- a type of ride-hailing in which riders share vehicles with
other riders -- has become a common travel mode in some major cities. This type
of shared ride option is currently provided by transportation network companies
(TNCs) such as Uber, Lyft, and Via and has attracted increasing numbers of
users, particularly before the COVID-19 pandemic. Previous findings have
suggested ridesplitting can lower travel costs and even lessen congestion by
reducing the number of vehicles needed to move people. Recent studies have also
posited that ridesplitting should experience positive feedback mechanisms in
which the quality of the service would improve with the number of users.
Specifically, these systems should benefit from economies of scale and
increasing returns to scale. This paper demonstrates evidence of their
existence using trip data reported by TNCs to the City of Chicago between
January and September 2019. Specifically, it shows that increases in the number
of riders requesting or authorizing shared trips during a given time period is
associated with shorter trip detours, higher rates of riders being matched
together, lower costs relative to non-shared trips, and higher willingness for
riders to share trips.
