Level of Service Based on Fundamental Diagram of Waterway Traffic Flow

Abstract

The level of service (LOS) is an important indicator of the performance of transportation facilities. This paper proposes to define and establish the criteria for waterway LOS based on the fundamental diagram of waterway traffic flow for the first time. Building on our understanding of waterway traffic flow, we propose to divide waterway LOS into four levels, I to IV from the best to the worst, and the traffic conditions corresponding to these levels are delineated respectively based on traffic density as the service measure expressed in passenger standard vessels per nautical mile per channel (pv/nmi/channel). Our research is conducted on the Yangtze Estuary water area with its historical Automatic Identification System (AIS) data which are processed using Python to extract waterway traffic flow characteristics, in particular, flow, space mean speed, and density. The results are used to construct the fundamental diagram of waterway traffic flow, based on which capacity and its associated optimal density is determined. Using optimal density as the basis, the waterway LOS criteria are proposed. Considering that the density of waterway traffic is small in magnitude compared with that of roadway traffic, a four-level designation from I to IV suffices the purpose of waterway performance indicator. This study can serve as the basis to evaluate the performance of waterway transportation systems as well as providing input to their planning, design, operations, and management.