bus bridge

Celebrating 35 Years As Civil Engineering Specialists

Client: Main Roads Location: Applecross, WA Value: $1.7 million Completion Date: May 1989

The works comprised the construction of an incrementally launched single cell, reinforced concrete box girder bridge over ’s busy Kwinana Freeway. The bridge permits east bound public buses to exit and enter the innermost lane on the Kwinana Freeway, heading north.

This bridge was proposed to allow public transport vehicles to cross the freeway to the dedicated bus lane, adjacent to the median, without causing disruption to the flow of traffic. This resulted in a faster and more efficient public transport service leading into Perth City.

Due to the location of the structure, the bridge was designed to withstand a collision load from the road traffic. Constructed in the corridors of an active freeway, it comprised of a single cell, prestressed concrete box girder with a cast in void. Incrementally launched, the highly curved member was supported on a concrete abutment that was built adjacent to the existing abutment used for Canning Bridge. Two smaller spans of 40m and 30m were used to transition from the curved span onto the Kwinana Freeway. The centre span was supported on two octagonal piers, chosen to match the piers supporting the canning bridge - kwinana freeway bus bridge | page 1 existing bridge. special features • The main bridge element was a curved prestressed concrete girder with a 1.5m diameter void and a radius of 77.5m with an overall length of 55.7m

• ~90% of the torsional forces resulting from the nature of the high curvature of the bridge was carried by the western abutment, resulting in a connection which only allowed longitudinal rotation, essentially making it a fully fixed connection

• A Honel expansion joint used on the northern abutment, allowing for longitudinal movement

• T-Roff beams were utilised for the straight sections of the bridge in order to minimise costs and time. A high degree of hog was induced into the beams to mitigate the angular appearance over the median column

• The substructure was designed to withstand a static load of 1000kN applied horizontally at a height of 1.2m above ground level

• Majority of the works was carried out during off peak traffic hours due to limited site access

• Parapets were cast and launched with the bridge deck

• Two temporary cast-insitu concrete piers were constructed to be used during the launching of the deck. These piers were demolished once the deck was installed.

canning bridge - kwinana freeway bus bridge | page 2

BOCOL CONSTRUCTIONS PTY LTD suite 13/7 kintail rd applecross wa 6153 / po box 80 applecross wa 6953 t (08) 9316 1148 / e [email protected] / w bocol.com.au ACN 008 904 005 | ABN 82 008 904 005 Celebrating 35 Years As Civil Engineering Specialists