There are more than ten thousand fewer truck trips as a result of a two-year-old scheme designed to boost productivity.
The high productivity motor vehicle permit scheme was introduced in an attempt to boost productivity by $180 to $500 million dollars a year by allowing longer and much heavier trucks on approved roads.
Some 2700 applications have been lodged with the Transport Agency, with about 1600 approved.
A spokesperson for the agency spokesperson, Harry Wilson, says the scheme has been a challenge, espeically from the perspective of upgrading bridges so they can take trucks weighing up to 62 tonnes in some cases. He says the agency has to prioritise the money available.
The agency is citing the case of Pan Pac Forest Products in Hawke's Bay as an example of how the scheme can boost productivity.
Hawke's Bay acting state highways manager Gordon Hart says Pan Pac has reduced its truck trips from Whirinaki to the Port of Napier by 5400 as a result of being able to carry 50% more freight. The company is saving 78,000 litres of fuel as a result.
Mr Hart says routes approved in Hawke's Bay have required little or no upgrade work, but it is taking longer to improve routes in which bridge strengthening is required because funding is tight.
The Transport Agency says this is also the case elsewhere on its state highways.
Local Government New Zealand president Lawrence Yule says councils are struggling to strengthen bridges on proposed routes because they have little or no money to do it and if the Government wants bridges upgraded faster, it needs to make more money available.
The Forest Owners Association says upgrading highways and local roads must be made a funding priority to make the most of the scheme.
The Transport Agency says it hopes to have 60% of the high volume areas of the state highway network approved for heavier or longer vehicles in the next few years.