MRACMAN is a new high-throughput backbone Metropolitan Area Network (MAN) aimed at interconnecting a collection of Local Area Networks (LANs) via simplified bridges. The backbone network and LANs are all based on a dual unidirectional slotted bus architecture. The simplified bridges (the backbone nodes) perform only simple buffering and routing logic. In addition, a high-throughput scheme, called Multislot Reservation Alternating Cycle Control (MRAC), is used as the medium access control protocol on both the backbone network and each interconnected LAN. MRACMAN, as will be shown, offers high throughput by means of efficient and parallel transmissions among all local LANs and the backbone network. Moreover, with a reasonable degree of traffic locality assumed, simplified bridges are guaranteed congestion-free. The paper provides performance evaluation and comparison via simulation results to demonstrate the feasibility of congestion-free bridges and throughput superiority of MRACMAN over other MANs.