The time vessels spend waiting in port is a major factor contributing to port performance. Vessel dwell times are the amount of time that vessels spend in port actively loading or unloading cargo, which in turn contributes to both port capacity and throughput performance. Shorter dwell times are usually desirable because vessel and marine terminal operating costs rise with dwell time.

In collaboration with the U.S. Army Corps of Engineers, BTS uses U.S. Coast Guard's (USCG) Automatic Identification System (AIS) data to calculate dwell times at berth for 3 ship types: container, liquid bulk (tanker), and roll-on/roll-off (Ro/Ro) vessels. AIS is a ship-to-ship and ship-to-shore maritime navigation safety communications system that monitors and tracks ship movements, primarily for collision avoidance. [1] Additional information on the BTS's methodology can be found at https://www.bts.gov/PPFS-Tech-Docs. 

Detailed interpretative analysis by ship type is provided for container, tanker, and Ro/Ro. Additionally, average container, tanker, and Ro/Ro vessel dwell times for these individual ports are shown in our online Port Profiles.

[1] 47 CFR §80.5