Vessel Dwell Times

The time vessels spend in a port is a major factor contributing to cargo throughput and performance. In collaboration with the U.S. Army Corps of Engineers, BTS has developed a method to estimate vessel dwell times at U.S. ports using the U.S. Coast Guard's (USCG) Automatic Identification System (AIS) data. 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
USCG has deployed a nationwide AIS (NAIS) system of towers and transceivers to receive and transmit AIS messages. The USACE has also deployed AIS transceivers at inland navigation locks. Together, these provide coverage for most of the ports profiled. An annual summary of the vessel dwell times by ship type is shown below.  These show that the dwell times for tankers are longer than those for container vessels, and both are longer than Ro/Ro vessel dwell times. Also, container and Ro/Ro vessel dwell times have increased while tanker dwell times have decreased. All vessel types experienced increased variability through 2020 and early 2021.
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