The cost of tow delays is a serious problem in a waterway network. One way to reduce the delay cost is to increase capacity at waterway locks. Planners must determine how much additional capacity to provide at particular lock sites and when to implement the capacity expansion projects. Answers for such project sizing and timing problems are difficult to obtain analytically. The use of a new approach for optimizing through simulation, called simultaneous perturbation stochastic approximation (SPSA), is investigated. This approach, which seeks optimal values for all decision variables after each pair of simulation runs, is quite promising for optimizing large problems relatively fast. A small numerical example tests how this simulation and optimization algorithm may be used to optimize lock capacities and implementation times.