A system for improving the logistics of medical transport in Ontario, Canada, developed through a series of Cornell master of engineering (M.Eng.) projects over the past three years, will soon be in use to help save lives.
Preliminary runs show that the new system may be cutting total travel distances by some 12 percent, and empty flights by 21 percent.
Since 2007, operations research and information engineering (ORIE) master's students have worked with Ornge, the nonprofit organization that provides medical transport for Ontario, to help improve the logistics of their service. Now a full-fledged system is in final testing phases and being rolled out for routine use.
Former graduate student Tim Carnes and ORIE professors David Shmoys and Shane Henderson have worked together in advising the M.Eng. medical transport projects. The Ornge project lead is Dr. Russell MacDonald, medical director for research and development and an associate professor at the University of Toronto.
After an early Cornell project focused on the basing of helicopters to be dispatched for emergencies, work shifted to the daily task of scheduling non-emergency medical transport planned for the following day. On an average day, Ornge flies or drives more than 10,000 miles to transport patients, and each year Ornge transports more than 20,000 patients.
The Flight Planning Optimization Tool developed by ORIE in partnership with Ornge uses operations research modeling as the basis for developing daily schedules from financial and aviation data. Doing so involves solving a challenging optimization problem: to find the best routes for aircraft, some of which can carry two patients, escorts or family members, and to determine the sequence of pickups and drop-offs along the way.
Before the tool was developed, flight planners developed routes, relying on software that identified the cheapest aircraft for a specific route. Test runs of the new approach, using more than 30 sample days of historical data, reduced total travel distance by 12 percent and reduced the number of flight legs with no patients on board ("empty legs") by 21 percent, according to Mahvareh Ahghari, project supervisor at Ornge.
Using results from an M.Eng. project that supplied proof of concept, Carnes first redeveloped the code to make it run quickly. He came up with a way to enumerate possible routes to efficiently construct an auxiliary optimization problem that can be solved, using commercial software, to obtain the desired optimal schedule.
"This made it conceivable for the first time to compute solutions to the scheduling problem that Ornge faces daily," Henderson said.
A follow-up M.Eng. project refined the cost data, after which computer science Ph.D. student Alex Fix added features to make the system more realistic (such as avoiding the transport of multiple patients when one of them is infectious) for putting the system into production at the Ornge headquarters near Toronto.
Carnes, who graduated in 2010 and is now a postdoctoral fellow at Massachusetts Institute of Technology, incorporated some of the results of his work with Ornge in his Cornell Ph.D. thesis.
Mark Eisner is a retired senior lecturer and part-time communications associate with the School of Operations Research and Information Engineering.
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