Bridges

This paper explores the design and construction of the integral bridge, trench retaining wall, and base slab structures within the Union and Mont Albert (UMA) Level Crossing Removal Project (LXRP) in Victoria, Australia. It discusses the design solutions implemented to address the constraints, optimise the construction program, and minimise the duration of critical rail and road closures.

The UMA LXRP separates road and rail traffic by lowering the rail line into an approximately 1.5km-long trenched underpass. The construction of five integral bridges spanning the trench rail corridor completes the connection of Union Road and Mont Albert Road, while providing pedestrian access across the rail corridor and to the new station platforms within the trench.

Situated on one of Melbourne’s busiest rail lines, the UMA LXRP involved complex staged construction and utility strategies to facilitate the construction of the bridge and trench structures. High groundwater levels and challenging ground conditions necessitated the use of a reinforced concrete base slab with tension micropiles to withstand large buoyancy uplift loads. Design and construction challenges were further exacerbated by a narrow rail corridor and the proximity of local roads and properties, preventing the rail line from deviating around the construction works. Consequently, much of the bridge and trench construction was completed during isolated rail corridor “occupations” in a staged approach.

To facilitate such an approach, the design team collaborated closely with the contractors to develop innovative “top-down” construction-staged solutions, while minimising road and rail closures. This paper explores the implementation and execution of design solutions such as the early installation of abutment segments and service beams beneath the existing rail tracks and roadway, staged construction of bridge elements around ‘live’ service beams, and the use of a base slab, tension piles and temporary props.

Opportunities for future development in design and on-site execution are presented in this paper for consideration.