On two-lane, two-way highways, pavement resurfacing is usually done by closing one lane at a time. Then, vehicles travel in the remaining lane along the work zone, alternating directions within each control cycle. Such a work zone can be analyzed as a one-way traffic-control system in which queuing and delay processes are analogous to those at a two-phase signalized intersection. Efficient scheduling and traffic control through work zones may significantly reduce the total cost. A model is presented for optimizing work plans, including zone lengths, work durations, starting times, pausing times (if any), and control-cycle times, for work zones on two-lane highways. This is done by minimizing total cost, including agency cost (maintenance cost and idling cost) and user cost (user delay cost and accident cost), while taking into account traffic-demand variations over time. Two optimization methods, Powell's and simulated annealing, are adapted for this problem and compared. In numerical tests, the simulated annealing algorithm yields better solutions using less computer time than Powell's method.