Work has begun on a new set of locks to allow giant cargo vessels to pass through the Panama Canal.
They will enable vessels known as post-Panamax ships to pass between the Atlantic and the Pacific Oceans, avoiding the longer route around Cape Horn at the southern tip of South America.
The contract is part of a $US5.25 billion project to expand the capacity of the canal.
It is scheduled for completion by 2014 - 100 years after the canal first opened. The 80km canal was built by the United States. It handles 5% of world trade.