Tasman Bridge

Tasman Bridge
Coordinates	42°51′54″S 147°20′33″E
Carries	Tasman Highway
Crosses	River Derwent
Locale	Hobart, Tasmania, Australia
Maintained by	Department of State Growth
Characteristics
Design	Prestressed concrete girder bridge
Total length	1,395 metres (4,577 ft)
Width	17.5 metres (57 ft)
Height	60.5 metres (198 ft)
Longest span	95 metres (312 ft)
Clearance below	46 metres (151 ft)
No. of lanes	5
History
Constructed by	Reed & Mallik
Fabrication by	Braithwaite & Co.
Construction start	May 1960 (1960-05)
Construction end	23 December 1964 (1964-12-23)
Opened	18 August 1964 (1964-08-18) (2 lanes) 23 December 1964 (1964-12-23) (4 lanes) 18 March 1965 (1965-03-18) (official) 8 October 1977 (1977-10-08) (reopened)
Statistics
Daily traffic	73,029 (May 2019)
Location

The Tasman Bridge is a prestressed concrete girder bridge connecting the Tasman Highway over the River Derwent in Hobart, Tasmania, Australia. When it opened on 29 March 1965, the Tasman was the longest prestressed concrete bridge in Australia, with a total length measuring 1,396 metres (4,580 ft), including approaches. The bridge provides a vital link between Hobart's city centre on the western shore and the City of Clarence on the eastern shore. Averaging 73,029 vehicle crossings per day, the bridge is the highest volume road section in Tasmania. It features five lanes of traffic including a central lane equipped for tidal flow operations and separated shared-use walkways on both sides, with ramp upgrades for improved access and cyclists completed in 2010.

The Tasman Bridge gained national attention following the Tasman Bridge disaster. On 5 January 1975, the SS Lake Illawarra, a 140-metre (460 ft) bulk ore carrier, collided with the pile capping of pier 18 and then pier 19. This led to the collapse of three unsupported sections of the bridge deck, sinking the vessel and resulting in the loss of twelve lives. The disaster split the city in half, forcing commuters living on the eastern shore to make a 50-kilometre (31 mi) round trip to the CBD via the next bridge to the north. During repairs, passenger ferries became a popular mode of public transit and a temporary bailey bridge was constructed 10 kilometres (6.2 mi) to the north of the Hobart CBD, bridging Dowsings Point and Cleburne Point on the eastern shore. After two years, the Tasman Bridge reopened on October 8, 1977. The Bowen Bridge was subsequently constructed to mitigate any future failure of the Tasman Bridge.

In June 2022, the Tasmanian transport ministry revealed a $130 million investment in the Tasman Bridge, the largest since its 1977 reconstruction. Designed by GHD Group with a target completion date set for 2025, the upgrades encompass wider dedicated paths for cyclists and pedestrians, increased barriers between vehicles and pedestrians, improved lighting and digital signage.

History

During the 1950s, Hobart's eastern shore underwent substantial expansion due to the opening of the Hobart International Airport at Cambridge in 1956. By 1957, the airport was the country's fifth busiest, and the surge in air travel, 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.

Design

In 1956, Tasmania's Department of Public Works commissioned Maunsell & Partners Pty Ltd to design the new River Derwent crossing. 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 nineteen 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 then-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.

Construction

The Tasman Bridge under construction, while the Hobart Bridge remains in place (1964)

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 favorable conditions of the riverbed, consisting of bedrock, dolerite, and basalt beneath the silt, provided stability for the bridge's foundations.

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 18 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.

Disaster

Main article: Tasman Bridge disaster

On 5 January 1975, the Tasman Bridge was struck by the bulk ore carrier Lake Illawarra, bound for EZ Industries' Risdon Zinc Works with a cargo of 9,072 tonnes (10,000 short tons) of zinc concentrate. It caused two pylons and three sections of concrete decking, totalling 127 metres (417 ft), to fall from the bridge and sink the ship. Seven of the ship's crew were killed, and five motorists died when four cars drove over the collapsed sections before the traffic was stopped. A major press shot showed a Holden Monaro HQ and Holden EK perched balancing on the ledge.

The average depth of the river between pier 18 and pier 19 is 35 metres (115 ft), with the wreck of the Lake Illawarra lying on the bottom covered by a concrete debris, presenting no navigation hazard to smaller vessels.

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 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 city centre 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

The repaired bridge span, 2011

Reconstruction of the Tasman Bridge by John Holland in October 1975, focusing on improved safety measures, such as directing large vessels to pass slightly west of the original main navigation span, training personnel (or harbour pilots) to use a special laser lighthouse for navigation, and halting all road traffic during vessel transit. Additionally, the bridge was upgraded to accommodate a fifth traffic lane, utilising a Japanese method dubbed the "Nippon clip-on," and incorporating a reversible lane management system for tidal flow operations. After two and half years and an approximate cost of $44 million, the Tasman Bridge reopened to the public on 8 October 1977.

Operations

Tidal flow operations

The reversible lane system, designed to optimize vehicle flow throughout the day, operates with a traffic light system and a sign above each lane. These signs, working in tandem with the traffic lights, utilise a pulley system to periodically shift over their respective lanes. During morning peak hours, the middle lane directs traffic towards the city side (or western shore), while during evening peak hours, it points back towards the eastern shore. Outside of peak hours, the lane generally directs traffic towards the eastern shore. This adaptable lane configuration maximises the bridge's capacity and reduces congestion by efficiently utilising lanes according to current traffic demand.

LED upgrade

Tasman Bridge lit up in solidarity for Ukraine on the anniversary of the Russian invasion of Ukraine

In 2019 the Hobart City Council commissioned Decrolux to convert the Tasman bridge's fluorescent lighting with modern LED lighting. Spanning almost 3 kilometres (1.9 mi) and utilising 1,930 LEDs, the project was completed in 2021. The lights are remotely programmable and have been used to celebrate Dark Mofo and the Hobart Hurricanes, as well as to show support for causes including Women's Health Week and Men's Health Week.

Gallery

Panorama of the Tasman Bridge at night.

• 
  View of the bridge from the eastern shore
• 
  Looking towards the Tasman Bridge from Montagu Bay
• 
  Dinghy and the bridge.
• 
  The view of the Bridge from Mount Wellington
• 
  A view of the bridge from the river
• 
  Tasman Bridge from the Western shore
• 
  Entering the bridge from the eastern shore
• 
  Entering the bridge from the west side

See also

• List of bridge failures
• List of disasters in Australia by death toll

Sources

• Christensen, E.M.; Jones, M.C. (1997). Before They Built The Bridge: An Anecdotal History (National Library of Australia). Hobart, Tasmania, Australia. ISBN 0646319450.{{cite book}}: CS1 maint: location missing publisher (link)
• Official Opening - The Tasman Bridge, Hobart (opening ceremony pamphlet) (Libraries Australia). Tasmania, Australia: Department of Public Works. 29 March 1965. 65392892.
• Cashion, Douglas (authorised by) (1965). Tasman Bridge Construction (16mm Eastmancolor Composite Release Print (colour, sound)) (documentary film). Hobart, Tasmania: Department of Public Works Tasmania. Reference: AB869/1/2610 – via Libraries Tasmania.
• Lewis, Tom (1999), By Derwent divided : the story of Lake Illawarra, the Tasman Bridge and the 1975 disaster, Tall Stories, ISBN 0957735111
• Hensher, David A. (David Alan) (1977), Re-opening of the Tasman bridge: the effect on mode and route of travel for east-west travel, School of Economic and Financial Studies, Macquarie University, ISBN 978-0-85837-257-3
• Ludeke, Michael (2006), Ten events shaping Tasmania's history, Ludeke Publishing, ISBN 9780957928428
• Aplin, Neil; Transport Tasmania. Economic Planning and Research Division (1983), Feasibility of discharging bulk fuel tankers south of the Tasman Bridge, Economic Planning and Research Division, Transport Tasmania
• The Story of Two Bridges, Platypus Publications, 1965

External links

Media related to Tasman Bridge at Wikimedia Commons

• Live webcam view of Hobart including the Tasman Bridge
• Traffic camera view of the Tasman Bridge
• Archival photographs of construction of the Tasman Bridge: page 1, page 2.
• 1995 article about Tasman Bridge safety
• Hobart To Tasman Bridge 1938–2000
• Tasman Bridge at Structurae