An anonymous reader shares a report: A trio of MIT researchers recently tackled a tricky vehicle-routing problem when they set out to improve the efficiency of the Boston Public Schools bus system. Last year, more than 30,000 students rode 650 buses to 230 schools at a cost of $120 million. In hopes of spending less this year, the school system offered $15,000 in prize money in a contest that challenged competitors to reduce the number of buses. The winners -- Dimitris Bertsimas, co-director of MIT's Operations Research Center and doctoral students Arthur Delarue and Sebastien Martin -- devised an algorithm that drops as many as 75 bus routes. The school system says the plan, which will eliminate some bus-driver jobs, could save up to $5 million, 20,000 pounds of carbon emissions and 1 million bus miles (Editor's note: the link could be paywalled; alternative source). The computerized algorithm runs in about 30 minutes and replaces a manual system that in the past has taken transportation staff several weeks to complete. "They have been doing it manually many years," Dr. Bertsimas said. "Our whole running time is in minutes. If things change, we can re-optimize." The task of plotting school-bus routes resembles the classic math exercise known as the Traveling Salesman Problem, where the goal is to find the shortest path through a series of cities, visiting each only once, before returning home.