We present a simulation-based software system for evaluating Hub-and-Spoke transportation networks. A complete description of the software system, known as HUBNET, is presented. Major topics of discussion include the motivating problem environment of truckload trucking, the overall simulation solution architecture, and the primary components of the HUBNET system. The simulation driver, written in the SIMNET II language, is described in detail. Also discussed are the information management systems designed to create appropriate supporting information to drive the simulator and to integrate the software system with befitting data, and the user support facilities designed to enhance usability and to isolate the user of the system from detailed simulation coding tasks. Concluding remarks include a discussion of technology transfer and field use, and a discussion of ongoing and future research with the HUBNET simulator.