Potential of Taxi-Pooling to Reduce Vehicle Miles Traveled in Washington, DC

This paper presents a pilot study of taxi-pooling in Washington, D.C. to demonstrate its potential for city-wide vehicle mileage reduction with real-world taxi trip data. In the taxi-pooling problem, riders specify their origins, destinations, earliest departure times, and latest arrival times. Taking all requests into consideration, the system dispatcher determines which requests can be grouped and thus served by one taxi, without violating any user-specified time windows and taxi capacity. This paper first presents a mathematical programming model whose objective is to minimize the system-wide vehicle miles traveled. Then an efficient solution approach to this problem is proposed. Results from analyzing the case of Washington, D.C. show that the total vehicle miles traveled can be reduced by 18% if the average buffer time in their travel schedule is 25% of their direct travel time.