Western Distributor - Construction Information

The Western Distributor is the predominately elevated freeway skirting the western edge of the CBD, distributing traffic between the Harbour Bridge, the CBD, and the Western Suburbs. Due to the complex nature of on/off ramps, the entire route has a modest 70km/h speed limit.


Planning the Distributor

Lying entirely within the City of Sydney, the Western Distributor was not included in the County of Cumberland Planning Scheme, however the routes of the North Western, Western and Southern Expressways were all relative to a proposed western distributor, skirting the western edge of the CBD. An infantile proposal for the Western Distributor appeared in the City of Sydney's 1956 'Map of Proposed Expressways'.


Construction begins!

Harbour Bridge to Day Street

During the early 1960's it was realised that the arterial and surface street approaches to the Harbour Bridge could no longer cope with current and projected traffic volumes. Designs began for new expressway approaches to the bridge, and following the completion of the Warringah Expressway between the Bridge and Miller St, construction began on the first stage of the Western Distributor. This first stage, between the Harbour Bridge toll booths and Day St, involved the complete reconstruction of the southern terminus of the Bridge to allow for reversible traffic flow during peak periods.

The construction of this stage was part of a greater plan devised by the DMR: "The first stage of the Western Distributor, which is under construction, will complement the Warringah Expressway by extending this improvement south of the Bridge. It will ultimately be extended to connect with the planned Southern and Western Expressways by an interchange at Ultimo. There will also be a link with the North Western Expressway near Druitt Street." 1

The design of the Western Distributor here was primarily influenced by the need to provide grade separation of expressway traffic. Unfavourable topography and the close proximity of underground railway tunnels meant it wasn't practicable to carry the expressway below the street system. Therefore, it was necessary to carry the Western Distributor above the city streets on a viaduct.

The Department of Main Roads provides this description of its design for the Western Distributor: "Ultimately the Western Distributor is planned as a two-level viaduct. The top level will consist of a divided six-lane expressway provided mainly for through traffic between the Sydney Harbour Bridge and the Ultimo Interchange, which will be the commencement of the Southern and Western Expressways. The lower level will be mainly a collector-distributor road with a number of connections to the city streets. The southbound roadway on this level will commence at Margaret St and the northbound roadway will terminate at Jamison St."

"The first stage of the Western Distributor, now under construction, is the ultimate southbound carriageway of the upper level. It will consist of four 12-feet wide traffic lanes, two for each direction of travel, and without a median divider except at the northern end where the viaduct bifurcates to join the toll plaza. At the southern end the viaduct comes to ground at Day St. When the Distributor is extended, several of the spans on the southern end of the viaduct will be raised a maximum amount of 28 feet to allow for construction of the lower deck and restoration of the street system. Features to permit this raising are being incorporated into the construction."

"Part of the lower deck system, spanning Sussex St from Margaret St will be constructed with the present work in order to reduce interference to traffic in Sussex St during future construction and to give increased stability to the high columns placed over this section. This section of the deck, however, will not be used by traffic at this stage." 2

The abutment of the southbound viaduct structure, south of the Harbour Bridge toll plaza, is of unusual design due to the proximity to the underground railway tunnel. Because of the skew at which the viaduct crosses the tunnel, it was not practicable to span the length involved nor could a a conventional type abutment be used. To overcome this obstacle it was necessary to design a multi-cell abutment 168 feet long to spread the load over the tunnel roof. Further to this, supporting piers of up to 69 feet in height were needed to provide a suitable grade where the land drops away between Kent and Day Streets.

It was estimated that the cost of construction for this first stage would be $9.5 million (1970), 40% of which was property acquisitions.



Meanwhile, in June 1971, the Department of Main Roads announced that it would soon begin construction of the section of the North Western Freeway between the City and Glebe. In the words of the DMR: "The North Western Expressway will form part of the planned expressway route between the cities of Sydney and Newcastle. It will extend from the City at Druitt St via Glebe, Balmain and Drummoyne to Huntleys Point where it will connect with the Lane Cove Valley Expressway which, in turn, will join the Sydney-Newcastle Expressway at Wahroonga."3 At the time of this announcement, construction of this section of freeway was expected to commence towards the end of 1971 and it was expected that some of the work would be open by 1975, allowing the closure and demolition of Pyrmont Bridge.

In September 1972, both carriageways of the first stage were opened to traffic, followed by a temporary northbound onramp to the Distributor from Pyrmont Bridge.in December of that year.

Construction of the next section of the Distributor was commenced in late 1971 (this section was still known as the North Western Expressway at this time). Construction was quite difficult due to the 24/7 operation of the Darling Harbour Goods Yard, much of which is land reclaimed from Darling Harbour in 1925. The Department undertook construction of the substructure with its own forces before awarding contracts to construct the superstructure to private companies.

In 1976 the State Government announced that there would be no further construction of the North Western Freeway, bringing it to an abrupt halt at Harris St, Pyrmont. Major community opposition to the destruction of the closely settled communities of Rozelle, Balmain and Drummoyne was a major contributor to the decision.

In October of the next year, the Government announced the cancellation of the Western Freeway (Concord to City) and the Southern Freeway (St Peters to City), meaning the Distributor would never be extended to Ultimo or be constructed to its original two-level design.

The first section across Darling Harbour, the westbound viaduct from Day St to Harris St, was opened to traffic in May 1980. In conjunction with this stage were major traffic switches including: Pyrmont Bridge made one-way eastbound, Sussex St made one-way southbound between King St and Hay St; and Kent St was made one-way northbound between Liverpool and Erskine Streets. In Pyrmont, Harris St between the freeway viaduct and Union St was made one-way northbound while Pyrmont St was made one-way southbound between Union and Quarry Streets. The eastern abutment of Pyrmont Bridge was demolished, meaning city-bound motorists had to negotiate two sharp left turns to access either the City (via King St) or the Harbour Bridge.

Just over a year later (August 1981) the citybound viaduct from Pyrmont St to King St was opened to traffic, closing Pyrmont Bridge to vehicular traffic permanently. The bridge was slated for demolition to expand the port facilities at Darling Harbour but redevelopment intervened in the form of the Bicentennial Redevelopment Project. The railway yards were moved to Enfield and Chullora and Darling Harbour began its transformation into the entertainment, shopping and recreation precinct that it is today. Meanwhile, the Pyrmont streets suffered from the heavy traffic to/from the CBD and Victoria Rd.


Congestion had reached unbearable proportions on the Glebe Island Bridge and the streets of Pyrmont by 1984. The State Government proposed a new high-level crossing to replace the Glebe Island Bridge, coupled with an elevated freeway to join the bridge to the Darling Harbour Viaducts. The project, known as the Glebe Island Arterial, opened in December 1995 to complete the Western Distributor, and construction and history of this project is discussed in detail HERE.

Since the completion of the Anzac Bridge, the capacity of the Distributor needed to be addressed. As discussed above, the Distributor was originally designed as a two-level roadway and the parts constructed were those meant to collect and distribute traffic to/from the CBD. There was only one through lane between the Harbour Bridge and Anzac Bridge, with the other lanes exiting and entering at various city streets. A widening project was commenced towards the end of 2002, to widen the viaduct between King St and the Harbour Bridge to 6-lanes and provide two through lanes along the entire route. Luckily the foresight of the Department of Main Roads meant that there was sufficient room on the carriageway to provide two traffic lanes without shoulders, however, the viaduct did need some widening. This work was completed in January 2004.


Future Improvements& Extensions

The Western Distributor will carry a great deal more traffic in 2006, with the opening of the Cross City Tunnel which will markedly decrease the travelling time for trips between the Western and Eastern Distributors. Plans for a M4 East may see the western end of the Distributor, at Victoria Rd, reconstructed, although it seems unlikely because the RTA prefers a shorter tunnel option.

1 - Department of Main Roads NSW, Main Roads Journal Vol. 36 No. 1, September 1970, pg. 3
2 - Department of Main Roads NSW, Main Roads Journal Vol. 36 No. 1, September 1970, pg. 4-5
3 - Department of Main Roads NSW, Main Roads Journal Vol. 37 No. 1, September 1971, pg. 2

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