Heuristic is a technique designed to solve a problem that ignores whether the solution can be proven to be correct, but which usually produces a good solution or solves a simpler problem that contains or intersects with the solution of the more complex problem.

Wheel Chair Access at Airports (Flying Wheels)G. Zayas-Caban1,2, S. McDermott1, E. Dolzhenko2, Dr. N. Kong1

1Industrial and Management Systems Engineering, 2Mathematics

Long-term Decision Making• A wheelchair allocation problem.• Costs: wheelchair maintains, storage, labor• Labor Costs: fixed and variable.• Objective: place wheelchair storage facilities and allocate limited number of wheelchairs such that an aggregate cost is minimized.• Constraints: limited budget.• Capacitated Facility Location Problem (CFL).

Short-term Decision Making• A wheelchair routing problem.• Costs: labor cost, customer waiting cost, penalty incurred from unsatisfiable requests.• Labor costs: variable.• Objective: route wheelchairs to transfer disabledtravelers from arrival gates to departure gatessuch that an aggregate cost is minimized.• Constraints: time-window constraints, matchingconstraints.• Pickup and Delivery Vehicle Routing Problemwith Time Windows (PDVRTW).

Wheelchair access at airports, especially large airports serving as hubs of airline companies, is an important issue for the airline industry. Airline management must attempt to minimize relevant costs. Meanwhile, airline management has to consider customer satisfaction in wheelchair access. In fact, according to a report from the U.S. Department of Transportation, passengers filed 10,193 complaints with U.S. airlines in 2004, and about two thirds of the complaints were related to wheelchair access. Imagine many passengers have very little time and have to travel to a gate far away when they make connections at a hub or major city of an airline company. This is even challenging to normal travelers, not to mention disabled travelers. Therefore, decision making related to wheelchair access is critical to the success of airline companies. The problem becomes increasingly significant as the society is aging and the demand for wheelchair services is predicted to rapidly increase and even double.

REU 2006Poster No.IE.2

Research Extensions•Simulation model is developed to verify the optimal cost obtained from our analytic capacitated facility location (CFL) problem.•Stochastic program is developed to address uncertainty, e.g., weather, mechanical delays.

Future directions• Address the dynamic nature of the system• Develop an on-line decision making system.• Further consider uncertainty.

Results: We use the Minneapolis/St. Paul International airport (MSP) as our case study and consult for Northwest Airlines. Our study shows that for a large airport with high traffic flow it would incur that the optimal long-tem allocation cost is around $300,000 annually, and optimal short-term routing cost is around $90,000 annually.

Modeling: We present two modeling frameworks that in general, allow us to consider an airport of arbitrary size and traffic flow.

Mathematical Contest in Modeling (MCM): a contest where teams of undergraduates use mathematical modeling to present their solutions to real-world problems. Our team conducted this project during MCM 06, and won Meritorious Award.

Solution: • Long-term Decision Making: Exact Solution using commercial solver.• Short-term Decision Making: Meta-heuristics developed in C/C++.

Labor Cost Customer Waiting

Unmet Request Penalty

Fixed Labor Cost

Variable Labor CostStorage/Maintenance Cost