Tasman Bridge

About

The Tasman Bridge is a prestressed concrete girder bridge carrying the Tasman Highway over the River Derwent in Hobart, Tasmania, Australia. When it opened on 29 March 1965, it was the longest prestressed concrete bridge in Australia, with a total length of 1,396 metres (4,580 ft), including approaches. The bridge provides a vital link between the Hobart central business district on the western shore and the City of Clarence on the eastern shore. Averaging around 73,000 vehicle crossings per day, it carries the highest traffic volume of any road section in Tasmania. It features five lanes of traffic, including a central lane equipped for tidal flow operations, and grade-separated shared-use walkways on both sides, with ramp upgrades for improved access and cyclists completed in 2010. The bridge gained national attention following the Tasman Bridge disaster. On 5 January 1975, it was struck by the bulk ore carrier SS Lake Illawarra, bound for EZ Industries’ Risdon Zinc Works with a cargo of 10,000 tonnes (11,000 short tons) of zinc concentrate. The impact caused two piers and three sections of concrete decking totalling 127 metres (417 ft) to collapse, sinking the vessel and resulting...

During the 1950s, Hobart's eastern shore underwent substantial expansion due to the opening of the Hobart Airport at Cambridge in 1956. By 1957, the airport was the country's fifth busiest, and the surge in air travel, associated automobile usage and surrounding developments led to a notable rise in traffic, overwhelming the capacity of the existing Hobart Bridge. With its single carriageway struggling to manage escalating traffic volumes and frequent disruptions due to the lifting of the bridge's lift span for passing ships, a necessity emerged for a novel bridge solution. These challenges highlighted the pressing need for a new, more accommodating bridge designed specifically for the increased traffic flow without constant interruptions for maritime navigation.

In 1956, Tasmania's Department of Public Works commissioned Maunsell & Partners Pty Ltd to design the new River Derwent crossing. The stable foundation for the bridge was ensured by the favorable conditions of the riverbed between Queens Domain and Montagu Bay on the eastern shore, which includes bedrock, dolerite, and basalt beneath the silt. The engineers recommended a bridge supported by multiple piers due to the width of the water expanse, similar to that of the Sydney Harbour Bridge but requiring a comparable height to accommodate medium-sized cargo vessels. Consequently, a decision was made to construct a girder bridge featuring twenty-two spans, including a navigation span at its apex, with thirteen spans to the west and six spans to the east, each measuring 42.7 meters (140 ft) wide. To achieve the height of the 60.5-metre (198 ft) apex, a large sequence of interval spans was critical in the design to accommodate the weight of concrete required for each heightened pier, with its deepest pile measuring 81 metres (265 ft) below mean sea level.

Criticism of Premier Eric Reece arose in 1958 when concerns were raised by engineers about the susceptibility of the concrete design to potential ship collisions. Investigative reports revealed Reece's dismissal of objections during parliamentary proceedings in favor of the $14 million project over a slightly more expensive suspension bridge option.

The bridge was originally built to a design life of about 100 years.

Tenders were issued in April 1959, and contracts were subsequently awarded to Reed, Braithwaite, Stuart, and Lipscombe in November of the same year. Construction on the eastern shore viaduct commenced in May 1960. A labour force of over 400 workers were employed during peak construction.

Several prerequisites were crucial during construction. The old Hobart Bridge had to remain operational until the Tasman Bridge's completion, and shipping lanes along the River Derwent needed to stay open. The construction posed significant challenges for Hobart as it marked the city's largest and most expensive undertaking to date. Procuring construction equipment, such as jacks and wires, required sourcing from the UK, while reinforced steel had to be imported from the Australian mainland, contributing to the bridge's elevated cost, totaling £7 million, equivalent to $14 million in 2015.

The first two lanes bridge opened on 18 August 1964. The other two lanes opened on 23 December 1964. It was officially opened on 29 March 1965 by Prince Henry, Duke of Gloucester. Upon completion, the Tasman Bridge was the longest prestressed concrete bridge in Australia, utilising 46,000 tonnes (45,000 LT) of concrete and 5,300 tonnes (5,200 LT) of reinforcement steel.

In 1956, Tasmania's Department of Public Works commissioned Maunsell & Partners Pty Ltd to design the new River Derwent crossing. The stable foundation for the bridge was ensured by the favorable conditions of the riverbed between Queens Domain and Montagu Bay on the eastern shore, which includes bedrock, dolerite, and basalt beneath the silt. The engineers recommended a bridge supported by multiple piers due to the width of the water expanse, similar to that of the Sydney Harbour Bridge but requiring a comparable height to accommodate medium-sized cargo vessels. Consequently, a decision was made to construct a girder bridge featuring twenty-two spans, including a navigation span at its apex, with thirteen spans to the west and six spans to the east, each measuring 42.7 meters (140 ft) wide. To achieve the height of the 60.5-metre (198 ft) apex, a large sequence of interval spans was critical in the design to accommodate the weight of concrete required for each heightened pier, with its deepest pile measuring 81 metres (265 ft) below mean sea level.

Criticism of Premier Eric Reece arose in 1958 when concerns were raised by engineers about the susceptibility of the concrete design to potential ship collisions. Investigative reports revealed Reece's dismissal of objections during parliamentary proceedings in favor of the $14 million project over a slightly more expensive suspension bridge option.

The bridge was originally built to a design life of about 100 years.

Tenders were issued in April 1959, and contracts were subsequently awarded to Reed, Braithwaite, Stuart, and Lipscombe in November of the same year. Construction on the eastern shore viaduct commenced in May 1960. A labour force of over 400 workers were employed during peak construction.

Several prerequisites were crucial during construction. The old Hobart Bridge had to remain operational until the Tasman Bridge's completion, and shipping lanes along the River Derwent needed to stay open. The construction posed significant challenges for Hobart as it marked the city's largest and most expensive undertaking to date. Procuring construction equipment, such as jacks and wires, required sourcing from the UK, while reinforced steel had to be imported from the Australian mainland, contributing to the bridge's elevated cost, totaling £7 million, equivalent to $14 million in 2015.

The first two lanes bridge opened on 18 August 1964. The other two lanes opened on 23 December 1964. It was officially opened on 29 March 1965 by Prince Henry, Duke of Gloucester. Upon completion, the Tasman Bridge was the longest prestressed concrete bridge in Australia, utilising 46,000 tonnes (45,000 LT) of concrete and 5,300 tonnes (5,200 LT) of reinforcement steel.

On 5 January 1975, the SS Lake Illawarra, a 140-metre (460 ft) bulk ore carrier, collided bow first with the pile capping of Pier 19 and then amidships with Pier 18 while en route to EZ Industries ' Risdon Zinc Works with a cargo of 10,000 tonnes (9,800 long tons; 11,000 short tons) of zinc concentrate. These successive impacts led to the collapse of both piers, their supporting pylons, and three unsupported sections of the bridge deck spanning 127 metres (417 ft), causing the vessel to sink and resulting in the deaths of seven crew members. Five motorists lost their lives when four cars drove over the collapsed sections before traffic was halted. A major press shot showed a Holden Monaro HQ and Holden EK perched balancing on the ledge.

The breakage of an important arterial link isolated the residents in Hobart's eastern suburbs – the relatively short drive across the Tasman Bridge to the city suddenly became a 50-kilometre (31 mi) journey via the estuary's next bridge at Bridgewater. The only other vehicular crossing within Hobart after the bridge collapsed was the Risdon Punt, a cable ferry which crossed the river from East Risdon and Risdon, some five kilometres (3.1 mi) upstream from the bridge. It was totally inadequate, carrying only eight cars on each crossing, and although ferries provided a service across the river; it was not until December 1975 that a two lane, 788-metre-long (2,585 ft) bailey bridge was opened to traffic, two kilometres (1.2 mi) to the north from Dowsing Point to Cleburne Point thereby restoring some connectivity. The bailey bridge remained in use until replaced by the Bowen Bridge in 1984.

The separation of Hobart saw an immediate surge in the small and limited passenger ferry service then operating across the river. In a primary position to provide a service were the two ferries of Bob Clifford. He had introduced the locally-built ferries Matthew Brady and James McCabe to the river crossing, from the Hobart central business district to the eastern shore, shortly before the collision. These were soon joined by the MV Cartela, a wooden vessel of 1912 vintage, and Kosciusko, Lady Ferguson and Lady Wakehurst that were loaned by the New South Wales Public Transport Commission.

Following the Tasman Bridge Disaster, former-Premier Eric Reece maintained his defence of the chosen bridge design. Reece argued that the selected design was the sole financially viable option for the state at that time, despite the construction costs doubling throughout the project's execution.

Reconstruction of the Tasman Bridge by John Holland commenced in October 1975. Due to the amount of debris at the foundations, engineers decided not to rebuild Pier 18. Pier 17 on the western side of the gap was reinforced, and the pile cap and shaft of the pier above water level were replaced. A new pier was built at the site of the decimated Pier 19, and the existing Pier 20, on the eastern side of the gap, was repaired and strengthened. A new span, about 85.5 metres (281 ft) long, was built in steel box girder construction between piers 17 and 19, and another new, prestressed concrete span, about 42.5 metres (139 ft) meters long, was built from the new Pier 19 to Pier 20.

The annual expenditures on the Tasman Bridge reconstruction were $1.7 m in 1974–75; $12.3 m in 1975–76; $13.2 m in 1976–77 and $6.1m in 1977–78. After two and half years and an approximate cost of $44 million, the Tasman Bridge reopened to the public on 8 October 1977.