Data Transport Networks: Case Studies in a Public Transit Environment

Ethernet has become the de facto standard for providing data transport not only throughout the Internet but also for numerous private and industrial networks. Before Ethernet's dominance, circuit-switched networks (or time-division multiplexed networks such as synchronous optical network (SONET) are popular choices for applications that require flexible and reliable data transport. Over the past ten years, packet-switched networks in general (and Ethernet in particular) usurped the role formerly played by these circuit-switched networks. But is this a good development given that not all applications that require data transport are created equally? This article explores the current trend of using packet-switched as opposed to circuit-switched networks in the context of providing data transport for rail-based public transit agencies and, after examining five case studies, draws conclusions that are relevant for public transit agencies.