SENSEable City: Ride-sharing for Efficiency

Cellphone apps that find users car rides in real time are exploding in popularity: The car-service company Uber was recently valued at $18 billion, and even as it faces legal wrangles, a number of companies that provide similar services with licensed taxi cabs have sprung up.
What if the taxi-service app on your cellphone had a button on it that let you indicate that you were willing to share a ride with another passenger? How drastically could cab-sharing reduce traffic, fares, and carbon dioxide emissions?
Authoritatively answering that question requires analyzing huge volumes of data, which hasn’t been computationally feasible with traditional methods. But in today’s issue of the Proceedings of the National Academies of Sciences, researchers at MIT, Cornell University, and the Italian National Research Council’s Institute for Informatics and Telematics present a new technique that enabled them to exhaustively analyze 150 million trip records collected from more than 13,000 New York City cabs over the course of a year.
Their conclusions: If passengers had been willing to tolerate no more than five minutes in delays per trip, almost 95 percent of the trips could have been shared. The optimal combination of trips would have reduced total travel time by 40 percent, with corresponding reductions in operational costs and carbon dioxide emissions.

[From a story by Larry Hardesty on the MIT News -- read more.]