Sydenham (Illawarra Line) Underbridge | NSW Environment & Heritage

Culture and heritage


Sydenham (Illawarra Line) Underbridge

Item details

Name of item: Sydenham (Illawarra Line) Underbridge
Other name/s: Sydenham - M50 Over I00 & M24 Flyov
Type of item: Built
Group/Collection: Transport - Rail
Category: Railway Bridge/ Viaduct
Primary address: , Sydenham, NSW 2044
Local govt. area: Marrickville


The curtilage is limited to the footprint of the bridge, abutments and wing walls.North: Rear of abutments and wing wallsSouth: Rear of abutments and wing wallsEast: Line through edge of steel bridge and end of wing wallsWest: Line through edge of steel bridge and end of wing walls
All addresses
Street AddressSuburb/townLGAParishCountyType
 SydenhamMarrickville  Primary Address


Organisation NameOwner CategoryDate Ownership Updated
RailCorpState Government 
RailCorpState Government 
RailCorpState Government 

Statement of significance:

The Illawarra Line Flyover is of local significance as the largest item of original infrastructure on the Botany Line. The bridge is a good representative example of a riveted steel Pratt truss rail bridge.
Date significance updated: 20 Oct 09
Note: The State Heritage Inventory provides information about heritage items listed by local and State government agencies. The State Heritage Inventory is continually being updated by local and State agencies as new information becomes available. Read the OEH copyright and disclaimer.


Designer/Maker: Engineering staff, Way and Works Branch, NSWGR
Builder/Maker: Day labour
Physical description: Single span, single track, steel Pratt truss over the Illawarra lines, with 37.5 m span between brick abutments.
Physical condition and/or
Archaeological potential:
The bridge is in good condition with the following defects: mild corrosion of truss, stringers, cross girders and bracing members
Date condition updated:20 Oct 09
Further information: 2012 July - management of this item was transferred to ARTC, however the line remains in RailCorp ownership.
Current use: Carries the single track Botany Line over the Illawarra Lines.
Former use: Nil


Historical notes: A goods line from Marrickville to the industrial area at Botany was planned c1914, as an extension of the Metropolitan Goods Lines, but was deferred until after World War I. In the early 1920s the project was resumed. All the bridges were erected prior to the earthworks being carried out because the fill material was at the Botany end of the line. Construction began at the Botany end of the line and proceeded towards Marrickville. For the last high level section from Sydenham to Marrickville, the embankment was formed by a method commonly used in the USA. A temporary timber trestle viaduct was built such that the ballast trains from Botany could tip the sandy material through the open transom deck to gradually build up the embankment. Eventually the temporary trestle viaduct was filled over and abandoned. The Botany Line was opened on 11 October 1925.

Pratt Trusses were introduced to Australia from the U.S in 1892 with the construction of the light-rail Yass Tramway. Thereafter they became the standard for Main Line railways for spans over 30 metres. While previous forms of truss had lent themselves to construction from timber, with stocky timber sections with good compressive and buckling resistance forming the diagonal members, the Pratt Truss reversed the direction of load in the diagonal members, enabling light rods or flat bars to be used in tension, making steel trusses highly efficient. The New South Wales railways continued to employ the use of steel Pratt trusses for major bridge crossings until the advent of reinforced and prestressed concrete in the 1970’s.

The Botany Line was opened on 11 October 1925.

Historic themes

Australian theme (abbrev)New South Wales themeLocal theme
3. Economy-Developing local, regional and national economies Transport-Activities associated with the moving of people and goods from one place to another, and systems for the provision of such movements Building the railway network-

Assessment of significance

SHR Criteria a)
[Historical significance]
The Illawarra Line Underbridge has historical significance as part of the original infrastructure for the Botany Line.
SHR Criteria c)
[Aesthetic significance]
The Illawarra Line Underbridge has technical significance as the largest item of infrastructure on the Botany Line.
SHR Criteria g)
The Illawarra Line Underbridge is a highly representative example of Pratt Truss style steel rail bridge.
Integrity/Intactness: The bridge is of high integrity, retaining its original fabric in good condition.
Assessment criteria: Items are assessed against the PDF State Heritage Register (SHR) Criteria to determine the level of significance. Refer to the Listings below for the level of statutory protection.

Recommended management:

1. Conservation principles: Conserve cultural heritage significance and minimise impacts on heritage values and fabric in accordance with the ‘Australia ICOMOS Charter for Places of Cultural Significance’. 2. Specialist advice: Seek advice from a qualified heritage specialist during all phases of a proposed project from feasibility, concept and option planning stage; detailed design; heritage approval and assessment; through to construction and finalisation. 3. Documentation: Prepare a Statement of Heritage Impact (SOHI) to assess, minimise and prevent heritage impacts as part of the assessment and approval phase of a project. Prepare a Conservation Management Plan (CMP) prior to proposing major works (such as new additions, change of use or proposed demolition) at all places of State significance and all complex sites of Local significance. 4. Maintenance and repair: Undertake annual inspections and proactive routine maintenance works to conserve heritage fabric in accordance with the ‘Minimum Standards of Maintenance & Repair’. 5. Movable heritage: Retain in situ and care for historic contents, fixtures, fittings, equipment and objects which contribute to cultural heritage significance. Return or reinstate missing features or relocated items where opportunities arise. 6. Aboriginal, archaeology and natural heritage: Consider all aspects of potential heritage significance as part of assessing and minimising potential impacts, including Aboriginal, archaeology and natural heritage. 7. Unidentified heritage items: Heritage inventory sheets do not describe or capture all contributory heritage items within an identified curtilage (such as minor buildings, structures, archaeology, landscape elements, movable heritage and significant interiors and finishes). Ensure heritage advice is sought on all proposed changes within a curtilage to conserve heritage significance. 8. Recording and register update: Record changes at heritage places through adequate project records and archival photography. Notify all changes to the Section 170 Heritage & Conservation Register administrator upon project completion.


Heritage ListingListing TitleListing NumberGazette DateGazette NumberGazette Page
Heritage Act - s.170 NSW State agency heritage register     

References, internet links & images


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Data source

The information for this entry comes from the following source:
Name: State Government
Database number: 4805746

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