Ann Melissa Campbell (PhD OR 2000) is an associate professor in the Tippie College of Business at the University of Iowa. Her research interests include routing and related distribution problems, including new network design problems based on challenges faced by UPS and new delivery pricing problems inspired by e-grocers. She also studies stochastic routing problems and efficient ways to solve them.

One of the problems she examined for UPS involves how to design a delivery network to move ground shipments from their origins to their destinations in a cost-efficient manner that satisfies promised delivery time commitments. This is a problem that has become increasingly challenging for companies such as UPS, as more customers are opting for the shorter delivery times that many ground freight companies now offer. At the same time, completely redesigning a company's delivery network based on these new delivery times is a very expensive proposition.

Campbell and co-authors Barrett Thomas (also at the University of Iowa) and Hui Chen (a former PhD student at Iowa and now a senior analyst at Northwest Airlines) have focused on a version of the problem where none of the hubs move, since the hubs would be the most expensive part of the network to change. Each "connection" represents a truck and a driver carrying ground freight from one hub to another. From each hub, there may be connections going to a single hub or to many other hubs. The number of connections has a significant impact on cost (as a truck and a driver represent a substantial investment) and on the ability to satisfy all promised delivery time commitments. Thus, Campbell, Thomas, and Chen specifically examine how to find the best possible set of connections that satisfy delivery time commitments given a limit on the total number of connections that may be used.

For many potential scenarios, there is not a feasible network that satisfies all delivery time commitments, so they measure the amount of violation of these commitments and seek to minimize either the maximum violation or the total sum of violations. For the maximum violation version of the problem, they have developed algorithms that solve several versions of the problem exactly. For the total sum version, exact solutions are not possible, but the authors have created some clever heuristics that capitalize on the solution structure.

In their computational experiments based on different ground networks in the United States, they found the solutions to problems with lower budgets always took on the appearance of connecting each hub to a "superhighway" going across the country. As budgets increase, the superhighway remains, but with additional connections added. This solution structure reveals the importance of having high-flow lanes and prioritizing movement of freight on these lanes to promote service quality and customer satisfaction.

Campbell received a prestigious NSF CAREER grant in 2003 and was awarded a Hesse Fellowship at the University of Iowa in 2004. She was named an associate editor of Transportation Science in 2007 and has authored twenty journal articles and four book chapters.

This article fist appeared in the Fall 2009 issue of Industrial & Systems Engineering, the alumni magazine of the Stewart School of ISyE.