New Zealand's economy relies heavily on its roading network to move its primary produce to ports for shipping to overseas consumers. The transport and export industry sectors have for some time called for a review of current vehicle weights and dimension limits in an effort to increase transport productivity. This paper reports on a new project to investigate the safety and economic effects of altering heavy vehicle weight limits, either on the entire road network, or on a selected network of routes. The methodology used in this project has included examining the safety and bridge impacts of a spread of vehicle types and gross weight limits, refining the weight limit options, and ascertaining the costs of the associated geometric, pavement, and environmental impacts. These impacts have been included in an overall economic analysis. A final project report covering the main findings has been completed, and recommendations from the project have been presented to the government agency that is considering the current mass and dimension limits. Results indicate that the freight benefits from altering vehicle weights and/or dimensions would outweigh the costs both for the entire road network and for a selected network. However, it appears that the implementation of any changes must be combined with a rationalisation of the charges levied on heavy vehicles together with the promotion of better performing combinations by the introduction of performance based standards. The views expressed in this paper are entirely personal and should not be relied upon as representing those of Transit New Zealand or Government policy. The Government has not to date considered the issue of changing heavy vehicle mass and dimension limits. (a)
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