Launch of Twin Steel Bridges Over Main Northern Railway at Sandgate, NSW: Temporary Works Design
- Publication no: ABC-DES401-14
- Published: 22 October 2014
The developed design of the 112-metre long twin superstructures included five fabricated steel I girders composite with a cast-in-place deck slab. These two decks were constructed on the southern roadway approach ramp and launched over the rail corridor during single-night track possessions. The rail corridor comprises six tracks, four of which carry coal between the mines in the Hunter Valley and the port of Newcastle and two which carry intercity passenger and freight traffic. A key consideration in developing the construction methodology was to ensure that the decks could be launched into place with absolute assurance that there would be no delay in executing the launch and delaying reopening of the rail corridor. Any interruption to the services on this busy strategic rail corridor would attract a significant cost penalty.A feature of this crossing is the 45 degree skew angle of permanent supports which align parallel to the rail corridor.This paper presents the methodology adopted for the design development and implementation of the temporary works required for the launch of the superstructures supporting only two of the five steel I girders as opposed to the original intention of supporting all five girders. A two girder supported launch provided far better definition of induced actions, providing a higher level of assurance that the launch would be completed safely over a short duration track possession.