Bridges

The revision of AS(AS/NZS) 5100 series has resulted in key changes to the provisions for train braking loads, dynamic load allowance, train collision loads, bridge bearings and design for light rail bridges. Longitudinal rail force provisions have been modified with revisions to the existing empirical formulae and the introduction of an alternative rational method for deriving these forces for complex bridge arrangements, and rail loading patterns. The rational method uses a first principles approach for determining the longitudinal rail forces applied to a bridge which can result in significant economies for long bridges in particular. The dynamic load allowance (DLA) has been revised by considering international standards and a recent study by ARTC. The maximum DLA value has been reduced from 160 down to 67% for bending stress. The recent pot bearing failures necessitated more stringent durability requirements for rail bridge bearings. New provisions have been introduced for light rail bridges. This paper discusses the new provisions and how to implement them.