A generic approach to the problem of optimal coordinated ramp metering control in large-scale motorway networks is described that is implemented in the software tool Advanced Motorway Optimal Control. In this approach, the traffic flow process is modeled by use of a second-order macroscopic traffic flow model. The overall problem of coordinated ramp metering is formulated as a constrained discrete-time nonlinear optimal control problem, and a feasible-direction nonlinear optimization algorithm is employed for its numerical solution. The control strategy's efficiency is demonstrated through its application to the 32-km long Amsterdam ring road. A number of different scenarios with regard to the number of controlled ramps and the available storage space are discussed in some detail. The results of the presented approach are very promising and demonstrate the high efficiency and general applicability of the optimal control methodology for motorway traffic control problems.