Mount Henry Bridge facts for kids
Quick facts for kids Mount Henry Bridge |
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| Carries |
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| Crosses | Canning River |
| Locale | Salter Point and Mount Pleasant, Western Australia |
| Maintained by | Main Roads Western Australia |
| Characteristics | |
| Material | Prestressed concrete |
| Total length | 660 m (2,170 ft) |
| Width | 40 m (130 ft) |
| Longest span | 75 m (246 ft) |
| Number of spans | 8 |
| Piers in water | 14 (7 per bridge) |
| History | |
| Construction begin | June 1979 |
| Opened |
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The Mount Henry Bridge is actually two bridges built side-by-side. They cross the Canning River in Perth, Western Australia. These bridges are very important because they carry the Kwinana Freeway and the Mandurah line railway.
At 660 meters long, the Mount Henry Bridge is the longest bridge in Western Australia! The first bridge opened in 1982. It carries cars heading south on the freeway and all the trains on the Mandurah line. The second bridge opened in 2006. It carries cars heading north on the freeway.
The first Mount Henry Bridge was built as part of a bigger project. This project extended the Kwinana Freeway. Construction started in June 1979 and finished in 1982. It cost about $13.5 million to build.
The second bridge was built later for the Mandurah train line. Engineers first thought about making the old bridge wider. But they decided to build a brand new bridge instead. This new bridge opened in January 2006. The Mandurah train line started running in December 2007. This second bridge cost around $23 million.
Contents
Building the Mount Henry Bridge
How the First Bridge Was Planned
Back in 1955, there was a plan for Perth's future roads. It suggested the Kwinana Freeway would cross the Canning River near the Mount Henry Peninsula. Later, in 1963, the plan changed the bridge's location slightly.
However, in 1967, the location was moved back to the Mount Henry Peninsula. This happened after people from the City of Melville objected to the new spot. Some people worried the freeway would spoil the natural beauty of the peninsula. But in 1975, the Parliament of Western Australia approved the Mount Henry Peninsula route.
Constructing the First Bridge
The first Mount Henry Bridge was part of a 6.5-kilometer extension of the Kwinana Freeway. Engineers from the Main Roads Department designed it. They looked at many different ideas before choosing the final design.
They picked a nine-span prestressed concrete bridge. This design looked good and allowed boats to still use the river easily. Construction started in June 1979. The builders used a special temporary structure that moved along as they built the bridge. This meant they didn't need to put temporary supports in the river.
Many concrete pieces for the bridge deck were made right there at the site. The bridge and freeway extension opened on May 9, 1982. The premier of Western Australia, Ray O'Connor, officially opened it.
Building the Second Bridge
The second bridge was built to make way for the Mandurah line train. This project also involved making changes to the Kwinana Freeway. The original bridge was made stronger to hold the weight of the trains.
Construction for the second bridge began in May 2004. At first, the plan was to widen the existing Mount Henry Bridge. But the construction company suggested building a completely new bridge next to it. This idea saved money and caused fewer traffic problems.
The new bridge was built using a method called "incremental launching." This means sections of the bridge were pushed out from one end. Because the bridge spans were quite long, temporary supports were used during this process.
The new bridge opened on January 22–23, 2006. This allowed workers to start preparing the original bridge for the train line. The entire project to add the second bridge cost $23 million. The Mandurah train line officially opened on December 23, 2007.
Bridge Design and Features
The original Mount Henry Bridge is 660 meters long and 28.8 meters wide. It's made from strong post-tensioned concrete. It's a special type of bridge called a "twin-cell concrete box girder bridge." It was built in sections.
This first bridge carried three lanes of freeway traffic in each direction. It also had a path for walking and cycling on both sides. These paths stuck out from the main bridge structure.
The second bridge was designed to look similar to the first one. Its supports were made to match the original piers. Even though the new bridge is a bit smaller, it blends in well. The second bridge actually overlaps the first one slightly, but they don't touch. This makes them look like one big, continuous bridge.
In 2024, the Mount Henry Bridge received a special award. Engineers Australia gave it an Engineering Heritage Marker. This shows how important and well-designed the bridge is. The bridge has also been on the City of South Perth's local heritage list since 2000.
