May 1 2007
The Western Link section of the Melbourne City Link Project will provide a long awaited connection between two major arterial roads, the Tullamarine Freeway and the West Gate Freeway.
The scope of work for the Western Link Project includes:
Upgrading and widening 7.5km of the existing Tullamarine Freeway to eight lanes between Bulla Road and Flemington Road. Additional features include the following:
- 7.5kms of widening of existing Freeway (2 lanes to 4 lanes)
- Approximately 265,000m3 bulk earthworks
- Upgrading or extending 15 bridges and overpasses
- Approximately 15km of noise attenuation walls to be constructed
- Extensive landscaping plans
Construction of a new 4.2km long elevated road joining the Tullamarine Freeway to the West Gate Freeway and 3.5km of on and off ramps constructed in addition to the main roadway. Additional features include the following:
- Match cast segmental span by span erection
- Approximately 210 Piers (5-20m high) constructed.
- Over 4,500 pre-cast concrete piles
- Approximately 3,500 segments to be produced
- Three lane segments weighing between 51-80t each
- Two lane segments weighing between 45-66t each
Construction of a new 490m balanced cantilever bridge to carry the Freeway link across the Yarra River. Additional features include the following:
- Construction of two 140m towers (6.5m2) for architectural purposes on either side of the bridge
- 30m clearance at high tide
- Dual Carriageway
Steel Design and Protection
This work included a stringent corrosion protection design life of up to 100 years with over 25 years to first maintenance undertakings required.
Design considerations assessed the corrosivity of the service environment, including the influence of prevailing winds, microclimatic effects, industrial influences and the severe effect of ultra violet exposure on materials over long periods.
After thorough research, hot dip galvanizing was employed on evidence of first cost saving and meeting long term requirement.
Elevated Road Enclosure-Noise Attenuation-Tube Structure
An Architectural Bypass
This unique component of the Western Link completes the freeway connection between the West Bound and Northern Freeways.
Due to its proximity to the Debneys Park estate, an innovative noise abatement structure has been designed to 'house' the passing traffic, over a 300 metre section of the elevated freeway.
Substantial enclosure of the roadway required a unique elliptical steel design to accommodate the road lanes passing through the architectonic tunnel.
The structure is also designed to accommodate an alignment curve with a radius of 750 metres in the progress of the road. Of the 1600 tonnes of steel involved in the structure, the steel frames and outer plating sections are hot dip galvanized while the internal frames are painted.
In this instance hot dip galvanizing was also chosen for aesthetic reasons, where architects recognised the powerful set of forms and futuristic appearance of the structure and preferred galvanizing for its natural silver metallic finish to match the scale and effect of their design.
The tube structure accommodates 6 x 3.5 metre wide traffic lanes in a 45-50 metre overall width.
Noise Wall Barriers
About 15 kilometres and 65,000 square metres of noise attenuation wall have been constructed in reflective cement panels with some sections containing further sound trap embedment features.
The panels are supported by hot dip galvanized steel columns of dimensions to accommodate the undulating terrain and contours of the wall design.
Soil Reinforcing
To meet the tight width constraints of the freeway space, a system of soil nails of some 6 metres in length were drilled and grouted as a means of accommodating retaining walls. The 6 metre steel rods were also hot dip galvanized to ensure the required steel service life in the buried environment.
Source: Galvanizers Association of Australia
For more information on this source please visit Galvanizers Association of Australia