New Fatigue Design Loadings for New Zealand Road Bridges
- Publication no: ABC-AAI304-14
- Published: 22 October 2014
Fatigue design of new bridges in New Zealand must consider the future demands from increasing heavy freight volumes and higher productivity vehicles. The new vehicles are designed to carry more freight with fewer trips to offset the reduced productivity arising from traffic congestion and to reduce overall fuel usage and carbon emissions. This has prompted a review of bridge design standards, as was required in Australia in the late 1990s and early 2000s. The research project for the NZ Transport Agency has investigated the current bridge fatigue loadings on main highways, and potential increases arising from adoption of higher mass vehicle configurations over the next decade or so. For assessment of existing bridges, a vehicle spectrum representing the seven most common vehicle types has been developed. The vehicle spectrum format, with 2 or 3 weight bands per vehicle type, is suitable for use with any type of material fatigue endurance equation.The project has found that a higher mass truck and trailer fatigue vehicle is more suitable for design use in New Zealand than the M1600 vehicle specified in Australian Standard AS 5100.2, and modifications to the AS 5100.2 application rules are proposed to cover the combined effects from more than one lane.