How Can Taxi Ridesharing Optimize Commuting Time?

Taxi ridesharing (TRS), in which multiple passengers “share” a single driver and vehicle en route to their respective destinations, can optimize the travel time of commuters and reduce the optimal number of taxis in urban settings, according to a January 7, 2020, study published inTransportation Science, a peer-reviewed academic journal, and co-authored by Dr. Christopher Monterola and Dr. Erika Fille Legara of the Asian Institute of Management.

The study noted, however, that less car ownership fixes traffic only if people share taxi rides, rather than swap their private car for a private taxi.

Some of the main objectives of the paper tackle the following:

• Is there an ideal taxi fleet size for a certain city size such that the demand for taxi service is met?
• How will this number change if commuters are more open to TRS? 
• Do commuters who share rides always sacrifice their total duration of travel (waiting time plus actual trip duration) for a more economical ride? 

Simulating an Entire Taxi System

To understand how ridesharing changes traffic dynamics, researchers from Singapore’s Nanyang Technological University, the Agency for Science, Technology and Research (A*STAR), and collaborators from AIM built a large-scale microscopic simulation of Singapore’s taxi network.

The simulation modeled both occupied and empty taxis, commuter bookings, boarding and drop-offs, route matching between passengers, and the roaming behavior of vacant taxis searching for riders. The system tracked the movement and status of every taxi and commuter across the road network in real time.

The researchers discovered a “phase transition” in taxi dynamics: there exists a tipping point between an oversaturated state, where demand exceeds taxi supply, and an undersaturated state, where too many taxis are on the road relative to demand.

“The boundary between these two phases effectively determines the optimal number of taxis a city should accommodate,” the researchers noted.

Why Ridesharing Can Save Time

The findings revealed that ridesharing does not always force commuters to sacrifice convenience for lower cost. Under certain conditions, sharing rides can actually reduce overall travel time.