The volume of cargo being moved between wharves on the Thames rose to 5.5million tonnes in 2015 - this is the fourth year in a row of tonnage growth.
This was also a 4% increase on the previous year’s total – 5.3million tonnes.
PLA director of planning and environment James Trimmer said: “These latest figures are great news for London communities and the environment.
“Every 20 tonnes of cargo moved by boat keeps a lorry trip off the capital’s busy roads.
"So with over 10million tonnes of material moved in the last two years that’s half a million truck trips saved.”
London's booming construction market, expanding businesses and transport schemes are all believed to be behind the latest growth in tonnage - sand, gravel and other building materials are easily shifted by river to wharves along the Thames.
To enable the construction of Crossrail three million tonnes of waste material from under London has been dug out and shipped to Wallasea Island in Essex, where the RSPB is using the soil to create a nature reserve.
Mr Trimmer added: “What’s encouraging is how organisations behind these massive projects which produce so much spoil and need such large volumes of materials are turning to the Thames and showing what can be done.
"We’re optimistic for the future, with both the Northern Line extension project and £4.1 billion Thames Tideway Tunnel scheme committed to using the Thames."