Bridges

The Torrens Road to Torrens River (T2T) project forms part of the overall North-South Road Corridor upgrade in Adelaide, South Australia and incorporates many components such as a new lowered motorway, road, service and pedestrian bridges, retaining walls and surface roads. This paper will discuss the Outer Harbor Railway Line bridge overpass (OHRB) that replaces an existing level crossing.

Whilst the alignment of the existing rail line has not been changed, it has been raised as far as practical in order to reduce the depth of the new lowered road and has resulted in a new 104 m long rail bridge with new 200m long approach ramp retaining walls to each abutment. Key performance indicators for the T2T project include minimal road traffic disruption with two lanes open in both directions at all times and no disruption to the rail traffic on the Outer Harbor Railway Line other than a 20-day occupation in January 2017.

This paper will discuss key features in the design and construction of the rail bridge and its approaches, particularly in relation to the short rail occupation:

• Approach ramps consisting of fill contained between precast concrete retaining walls up to 5m high
• Retaining wall and footing construction in a tight rail corridor with live rail operations of with more than 150 trains per day
• A 104m long three-span steel through girder rail bridge with a 39-degree skew and a maximum span of 40m carrying two rail tracks
• Large diameter bored pier footings with integral columns and stressed down headstocks
• Heavy lifting of three assembled bridge segments into place.