Mount Henry Bridge facts for kids
The Mount Henry Bridge is a very important bridge in Perth, Western Australia. It carries the Kwinana Freeway and the Mandurah railway line over the beautiful Canning River. This bridge is about 10 kilometres (6.2 miles) south of Perth's city centre. At 660 metres (2,165.4 feet) long, it's the longest road bridge in Western Australia! It connects the Mount Henry Peninsula with the suburb of Brentwood.
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Building the Mount Henry Bridge
The Mount Henry Bridge was built as part of a big project to extend the Kwinana Freeway. This work happened in the late 1970s and early 1980s. The bridge officially opened in 1982. A company called Clough was in charge of building it.
How the Bridge Was Made
The original bridge is made from a special type of concrete called post-tensioned concrete. It has nine sections, making it 660 metres long in total. The top part of the bridge, where cars drive, is about 28.8 metres wide.
The bridge has a unique shape, like a double box. The top part carries all the traffic. Below that, on the sides, there are special paths for people to walk and ride bikes. The bridge was built in pieces, using a method called "balanced cantilever construction." This means sections were added from both sides at once, keeping the bridge balanced.
Making the Bridge Bigger
Between 2004 and 2006, the Mount Henry Bridge was made wider and stronger. This was done to make space for the tracks of the Mandurah railway line, which is a train line.
Why the Bridge Was Widened
To add the new train tracks, a completely new structure was built right next to the original bridge. This new part overlaps the old bridge. Now, the original bridge carries three lanes of traffic going south and the two railway tracks. The new part of the bridge carries three lanes of traffic going north.
The new bridge was built carefully to make sure it looked good next to the old one. Its foundations are separate from the original bridge. Each support pillar for the new bridge has two columns that get narrower towards the top.
The new bridge was built using a method called "incremental launching." This means sections of the bridge were pushed out from one end, piece by piece, until the whole bridge was formed. Companies like Leighton Constructions helped build this new section.
