(AP) — In an effort to ease congestion at the nation’s busiest port complex, officials said Monday that they will start fining shipping companies whose cargo containers linger for too long at marine terminals.

The twin ports of Los Angeles and Long Beach said in a statement that arriving containers scheduled to be moved by trucks will be allowed to stay for nine days before fines start accruing. Containers set to move by rail can stay at the ports for three days.

After that, ocean carriers will be charged $100 per container, increasing in $100 increments per container per day, the statement said.

The new rules will go into effect Nov. 1.

“The terminals are running out of space, and this will make room for the containers sitting on those ships at anchor,” Port of Long Beach Executive Director Mario Cordero said in the statement.

It’s the latest step aimed at relieving the logjam of cargo ships that has interrupted the global supply chain. The backlog prompted the Biden administration to allow the port complex to operate 24 hours a day to try to get goods unloaded and out to consumers.

About 40% of all shipping containers entering the U.S. come through the Los Angeles and Long Beach ports.