Spit Bridge

The Spit Bridge
The Spit Bridge with its bascule deck opened
Coordinates	33°48′09″S 151°14′46″E
Carries	The Spit Road Motor vehicles Grade-separated shared pedestrian footpath and cycleway
Crosses	Middle Harbour
Locale	The Spit, Sydney, New South Wales, Australia
Begins	Mosman (south)
Ends	Seaforth (north)
Owner	Roads & Maritime Services
Heritage status	Roads & Maritime Services heritage and conservation register
Preceded by	Roseville Bridge
Characteristics
Design	Girder bridge with a bascule lift span
Material	Steel and concrete
Trough construction	Composite concrete
Total length	745 feet 6 inches (227.23 m)
Width	54 feet (16 m)
No. of spans	7
No. of lanes	4
History
Designer	NSW Department of Main Roads
Constructed by	Cleveland Bridge and Engineering Company
Construction start	1952 (1952)
Construction end	1958 (1958)
Construction cost	A£1,110,000
Opened	19 November 1958 (1958-11-19)
Replaces	The Spit Bridge (1924–1958)
Statistics
Daily traffic	~33,000 (2012)
Location
References

The Spit Bridge, a steel and concrete girder bridge with a bascule lift span across the Middle Harbour, is located 10 kilometres (6.2 mi) northeast of the central business district in Sydney, New South Wales, Australia. The bridge carries The Spit Road (A8) from a point called The Spit, and connects the suburbs of Mosman, on the south bank and Seaforth, on the north bank.

History

Construction of The (first) Spit Bridge in 1924. The punt may be seen in bottom left foreground.

Sydney's Lower North Shore and Northern Beaches were serviced initially by a rowing boat from as early as 1829. A hand-operated punt service began in 1850 and continued until 1889, when it was replaced by a steam punt.

In 1924, The (first) Spit Bridge was completed and opened. By 1927 the timber low–level bridge saw a 60% growth over that of the punt for the year prior to the bridge opening. The amount of traffic using the bridge was higher than expected and the subsequent revenue from tolls providing a financial boon for the government. Various plans were considered to reduce congestion including a high-level bridge and a bridge further upstream, leaving the existing bridge for local traffic; however none were enacted until after World War II. The NSW Government decided to build another low–level bridge at the same site.

Description

The Spit Bridge from Ellery's Punt Reserve.

Construction of the current bridge had commenced in 1952 and after delays was completed in 1958; and opened on 19 November 1958.

The Spit Bridge over Middle Harbour can be described as a steel and concrete girder bridge with a bascule lift span. The Spit Bridge comprises 7 spans of a total length of 745 feet 6 inches (227.23 m), has four traffic lanes with a width of 44 feet (13 m) and a pedestrian walkway of 5 feet (1.5 m) on either side. There are three spans at either end of the opening span. Each of the six fixed spans have four welded plate girders as the main members, with cross girders, but without stringers or horizontal bracing. The concrete deck is dowelled to the steelwork. The opening span (Span 4) is a single-leaf bascule. It has two main girders, with cross girders and stringers, covered by an open mesh steel deck.

The two footways are of concrete on the fixed spans, and steel on the bascule span. The piers either side of the opening span are flanked by fenders, and when the bridge is in the open position a navigation channel of 80 feet (24 m) wide is created. At the Mosman end the slab and two column piers rest on concrete piles driven into the sands of the harbour bed at a depth of between 40 and 50 feet (12 and 15 m). At the Manly end the harbour bottom slopes up steeply to outcropping rock on which the northern abutment sits. Piers 5 and 6 are double cylinder piers sitting on bedrock below the harbour bed. The main pier which supports the bascule span is Pier 4. It rests on four cylinders taken down to sandstone bedrock at a depth of between 45 to 75 feet (14 to 23 m) which is 75 and 105 feet (23 and 32 m) below mean sea level. The pier is box-like and supports all machinery for the operation of the bascule, including the operator's cabin. The approaches and abutments at each end are varied due to the nature of the topography. The southern abutment is built up from the sandy beach level and has a retaining wall faced with stone on either side. The northern abutment is resting directly on the rock on the western side and is built up on the eastern side with a retaining wall. Due to the variation in ground level on each shore there is a grade of 2.68% from south to north. Traffic across the bridge is regulated by traffic lights at either end (located at the end of Spans 2 and 6) and by roadway gates which operate as the bridge is about to open.

The bridge has two traffic lanes in each direction, with a tidal flow system established, while the approaches to it have three lanes in each direction. In 2007, the Roads and Traffic Authority found that traffic either side of the bridge doesn't return to normal for 15 minutes after the bridge is opened and reduced the number of bridge opening times.

Grade-separated shared pedestrian footpaths and cycleways are located on the bridge's western (upriver) and eastern (downriver) sides.

Heritage listing

The Spit Bridge was listed on the Roads & Maritime Services heritage and conservation register on 24 November 2003 with the following statement of significance:

The Spit Bridge, completed in 1958, is of state significance. It is a substantial landscape feature that has played a crucial role in allowing the development of the northern beaches suburbs to occur over the last 44 years. The Bridge is also extremely rare as it is the only lift bridge still operational on a major arterial road. As such, the Spit Bridge is representative of all the major lift bridges that were once a common sight throughout NSW. The relative lack of modification to the original design of the Bridge also contributes to its level of significance. Historically the Bridge has a high level of significance developed primarily through being part of an important local transport route that has been in operation over a large period of time in several different guises. The Spit Bridge Cultural Landscape also contains the remnant features and locales of the former bridge and punt crossing and the remains of other transportation links such as the tramways. These additional items add to the significance of the Bridge through their ability to add to contextualise the current bridge as a single element of the crossing points colourful history.

— Statement of significance, Heritage and conservation register, Roads & Maritime Services, 24 November 2003.

Alternative replacement options

The Spit Bridge forms part of the route from the Sydney central business district and Lower North Shore suburbs to Manly and the Northern Beaches. The next crossing is some distance upstream (north-west) at Roseville Bridge. The Roads and Traffic Authority announced in August 2006 that tenders had been called for widening of the bridge to six lanes, with two extra traffic lanes and a pedestrian/cycleway being added on the western side, and upgrades to the lifting mechanism. Construction was to have begun in 2007, however, the project was scrapped in May of that year. According to the government this was due to technical and engineering difficulties, according to the opposition it was because of political considerations. The increased cost estimates to $115 million were deemed to be not justifiable by the Minister for Roads Eric Roozendaal and the five–year plan was abandoned. Traffic delays either side of The Spit Bridge have been a problem for many years, not only on the approaches to the bridge itself, but also far up the hills on either side. Proposals to ameliorate delays have included widening the bridge, a tunnel linking the Warringah Expressway and the Burnt Bridge Creek Deviation, and a high-level bridge in place of the existing one. David Barr, the member for Manly, claimed in 2002 that the latter two were too expensive with $200 million estimated for a high-level bridge, and $1 billion for the tunnel. In 2009 it was reported that the Labor Government was reviewing a proposal for a tunnel from Cammeray to The Spit, linked to a new, higher bridge that would be able to let boats through without the need to be opened.

In 2014, Premier Mike Baird, also the member for Manly, announced plans to bypass Mosman and The Spit Bridge by constructing a $2–3 billion tunnel from Seaforth to Neutral Bay that would run underground beneath Military Road. In 2017, NSW Premier Gladys Berejiklian announced that the NSW Government will provide $77 million towards the construction of a tunnel to bypass The Spit Bridge. The tunnel, which is expected to take five years to build, will connect the Warringah Freeway from Cammeray and cross underneath Middle Harbour to meet up with the Burnt Bridge Creek deviation at Balgowlah. The proposed tunnel is to be located west of The Spit Bridge.

See also

• List of bridges in Sydney

External links

• The Spit Bridge opening times
• Live traffic camera - Manly Road
• Kass, Terry (February 2006). "RTA Thematic History: A component of the RTA Heritage and Conservation Register" (PDF). NSW Roads & Maritime Services (PDF) (2nd ed.). Government of New South Wales. Retrieved 12 January 2015.
• Wotherspoon, Garry (2010). "Spit Bridge". Dictionary of Sydney. Retrieved 8 October 2015. [CC-By-SA]
• instagram.com/simondrone (n.d.). Drone footage of The Spit Bridge (streaming video). Gold Coast Bulletin. {{cite AV media}}: |author= has generic name (help)