Great Western Highway

Great Western Highway is a From Railway Square, the highway follows Broadway south and west, to the intersection with City Road (Princes Highway), where the highway changes name to Parramatta Road and heads generally west towards Parramatta. Hume Highway (Liverpool Road) branches south-west at Summer Hill/Ashfield, and a short distance further west the majority of traffic is diverted off the highway onto M4 Western Motorway via the WestConnex tunnel at Ashfield. A short distance further west, on the northern fringes of Ashfield, the City West Link arterial road ends at a major junction with the highway at Frederick Street (which proceeds south to join Hume Highway).

The highway continues west as Parramatta Road, with a major intersection at Homebush West with the A3 arterial road. Although the A3 road is called "Centenary Drive" in this area, the on-/off-ramps are separately named Marlborough Road, carrying on the name of the surface road that was replaced by Centenary Drive. Further west, on the boundary between Lidcombe and Auburn, the highway intersects the A6 arterial road (St Hillier's Road / Silverwater Road).

Just south of Parramatta, the highway meets Woodville Road and continues west onto an on-ramp for M4 Western Motorway, while the highway-designated route turns sharply to the north along Church Street, before turning west again at the southern fringe of the Parramatta central business district, continuing west across western metropolitan Sydney to , north of the central business district, where it crosses the Nepean River via the 1867 Victoria Bridge. At , M4 Western Motorway reconnects with the highway as it begins its ascent into the Blue Mountains. It intersects with Darling Causeway at Mount Victoria which heads north to connect with Bells Line of Road. From Mount Victoria, the highway descends via Victoria Pass into the Hartley Valley and then passes through the western suburbs of Lithgow where it is joined by the Chifley Road, which links eastward back to Bells Line of Road. The highway continues generally west, intersecting with Castlereagh Highway west of Marrangaroo, and crosses Coxs River to ascend the Great Dividing Range to reach its highest point (at just east of Yetholme) and over the western ridge of the Sydney basin before dropping into the Macquarie Valley to reach its western terminus at Bathurst, at the junction of the Mitchell and Mid-Western Highways. Parramatta Road dates to the 1792 formation of a route linking Sydney to the settlement of Parramatta, formalised under the direction of Surveyor-General Augustus Alt in 1797. Parramatta Road became one of the colony's most important early roadways, and for many years remained one of Sydney's premier thoroughfares. By 1810, Parramatta Road had officially open to traffic and was financed during a large portion of the 1800s by a toll, with toll booths located at what now is Sydney University and the Duck River.

After protracted arguments first with Governor Ralph Darling and then his successor Richard Bourke, and ignoring orders, Mitchell surveyed, designed and had built what is now known as Victoria Pass, where the highway drops from the Blue Mountains into the Hartley Valley. Midway down the road had to be supported on a causeway formed by massive stone buttressed walls, where a narrow ridge connects two large bluffs. This ridge had to be widened and raised to give the highway a route from the upper to the lower bluff. Mitchell cut terraces into the sides of these bluffs to form a passage for the road. It is a testimony of Mitchell's vision and engineering skill that this route, almost unchanged, and using his 1832 stonework, is still in use. Because this pass brought the road into the Hartley Valley several kilometres south of the Mount York descent, it necessitated a new route as far west as Hartley to meet Cox's Road. This also is still in use as part of the highway.

In 1929 the Main Roads Board deviated the route north from Old Bowenfels to Marrangaroo, using Trunk Road 55 (Mudgee Road, today Castlereagh Highway). From Marrangaroo a new road was built westward, running south of Wallerawang to meet Mitchell's 1830 deviation immediately east of Mount Lambie. This route avoids the long, steep gradients either side of Cox's River, which were the main drawback of Mitchell's route.

Great Western Highway today therefore consists of Parramatta Road to Parramatta, the Great Western Road to Emu Plains, Coxs Road to Hartley (other than Mitchell's deviations at and Mount York), Mitchell's route from Hartley to Old Bowenfels, the Main Roads Board route from Old Bowenfels to Mount Lambie, Mitchell's road from Mount Lambie to Kelso, and McBrian's road from Kelso to central Bathurst.

thumb|right|Great Western Highway at [[Blaxland, New South Wales]]

Road classification

The passing of the Main Roads Act of 1924 through the Parliament of New South Wales provided for the declaration of Main Roads, roads partially funded by the State government through the Main Roads Board (later Transport for NSW). Great Western Highway was declared (as Main Road No. 5) on 8 August 1928, from the interchange with Parramatta Road and City Road in the City of Sydney, via Penrith, Katoomba, and Lithgow to Bathurst; to provide for additional declarations of State Highways and Trunk Roads, this was amended to State Highway 5 on 8 April 1929. Its eastern end was extended to the intersection of Broadway and Wattle Street on 22 February 1967 (part of Sydney's Ring Road 1 at the time). It was extended east again to its current terminus at Railway Square in Haymarket on 22 January 1993.

As the main route for traffic from the Blue Mountains into Sydney was superseded from Great Western Highway to the Western Freeway/Motorway from the 1970s, the definition of Great Western Highway as State Highway 5 outside inner Sydney remained virtually untouched, until the western extension of Western Freeway from Emu Plains to Lapstone in June 1993, resulting in a roughly-2km gap between the beginning of the motorway and the interchange with Russell Street where the highway recommences. updated road classifications and the way they could be declared within New South Wales. Under this act, Great Western Highway today retains its declaration as Highway 5, from the intersection of Broadway and Quay Streets at Railway Square in Haymarket to the interchange with M4 Western Motorway at Leonay, then from the end of Western Motorway at the interchange with Governors Drive at Lapstone to Bathurst.

21st century

In March 2026, Mitchell's Causeway and Victoria Pass were found to be unsafe and were closed indefinitely by Transport for NSW. Traffic was diverted at Mount Victoria via the Darling Causeway and Bells Line of Road rejoining the Great Western Highway at Bowenfels. The government subsequently announced that Mitchell's Causeway would be closed for at least three months. In May 2026, two consortia led by Gamuda Berhad and Seymour Whyte were shortlisted to rebuild the causeway.

Improvements

During 19th century

The first recorded major improvement to the route of Great Western Highway was the construction in 1806 of ten bridges along Parramatta Road.

In attempts to improve the gradient of the descent from the Blue Mountains plateau to the floor of the Hartley Valley, Lawson's Long Alley was opened in 1824. This still did not prove satisfactory and construction of a second deviation, known as Lockyer's Pass, was commenced. However this route was not completed, as its construction was abandoned in favour of construction of Mitchell's route via Victoria Pass.

Originally the Great Western Road crossed the Nepean River at Penrith by means of a ferry adjacent to the Log Cabin Hotel. This was superseded in 1856 by a bridge which was destroyed by a flood in 1857. A second bridge was opened in 1860, and was destroyed by the record flood of 1867. In the same year a new bridge, Victoria Bridge, was nearing completion adjacent to the road crossing, as part of the Penrith-Weatherboard (Wentworth Falls) section of the Main Western Railway. Its deck was modified to accommodate road traffic as well as the single-track railway. This bridge continued in dual use until 1907 when the current steel truss railway bridge was built alongside, and the 1867 bridge was given over solely to road traffic. This bridge remains in use for Great Western Highway. The design of this bridge is almost identical to that of the 1863 Menangle Railway Bridge, also over the Nepean River.

In 1870 the Denison Bridge, a wrought iron truss bridge, was built across the Macquarie River at Bathurst. This replaced an earlier wooden bridge.

During early 20th century

In the first few years of the 20th century the railway overpasses between Lapstone Hill and Mount Victoria were replaced as part of the duplication of the Main Western railway. These bridges were of brick arch construction. They were in turn replaced in the mid-1950s to obtain the necessary height clearances for overhead wiring for the electrification of the Main Western Railway from Penrith to Bowenfels.

In 1912 Victoria Pass was superseded by Berghofers Pass, which followed a similar route to Victoria Pass, but below it. It was more winding and thus longer, thereby affording a less steep climb. However rapid improvements in motor vehicle performance meant that in 1920 Victoria Pass was rebuilt to become the main route again.

After the ascent of the eastern escarpment by the Main Western Railway was deviated for the second time in 1913 to its current route via Glenbrook Gorge, the Great Western Road was also deviated at this point for a second time in 1926 by the then Main Roads Board, which rerouted it via the disused 1867 stone arch railway viaduct across Knapsack Gully and around the southern side of Lapstone Hill to gain the first plateau in the ascent of the Blue Mountains. As this viaduct had held only a single railway track, its deck was widened in 1939 to its present two lane configuration. The viaduct was closed to motor traffic when the M4 Motorway was extended west from Russell Street to connect to the highway at Lapstone in 1994.

West of Knapsack Gully, although now widened to four lanes, the 1926 route of the highway is still in use. It uses a long stretch of abandoned railway formation – the section from Zig Zag Street to Blaxland station is located on the original 1867 railway alignment. An indication of the need to divert the railway can be gained from the gradient of the highway as it climbs west from Hare Street to Lovett Street.

A number of deviations were built in 1929:

at Haslams Creek, , to straighten the road and provide a new bridge
between and , to remove an underpass and an overpass of the railway from the route of the highway
at Eusdale, Yetholme (in three sections) and Melrose (all west of Meadow Flat), to ease gradients.

In 1930 the level crossing at Bowenfels was replaced by an underpass.

Victoria Pass was upgraded in 1932 to give a constant width of 8.5 m, with a minor deviation built at the foot of the pass.

Upgrading since World War II

In 1957 a short deviation immediately west of Linden eliminated two narrow overpasses of the railway, both of which had right angle bend approaches from both directions. These bridges would have had to have been replaced in any event to allow for overhead wiring for the electrification to Bowenfels of the Main Western Railway. Such replacements occurred east of Linden, further west of Linden near Bull's Camp, east of Lawson, at Medlow Bath and east of Mount Victoria, and in these cases the replacement bridges were located at a skew angle to eliminate right angle bend approaches, with the earlier bridges left for pedestrian use.

In 1958 the 'Forty Bends’, where the Highway runs along the foot of Hassans Walls approaching Lithgow, were eased. The fact that this section of the highway is on the southern side of a very high escarpment poses severe ice problems during winter, due to the lack of sunlight.

In the early 1960s the highway was deviated east of Leura to cross under the railway at Scott Parade (which was itself part of the former highway route) and run along the north side of the railway to rejoin the previous route at Leura Mall.

In 1967, the highway was deviated to bypass Springwood shopping centre, eliminating two narrow underpasses of the railway from the highway route. The previous route remain in use for local traffic as Macquarie Road. In 1968 a dual carriageway 3 km deviation was opened at Prospect. This replaced the only winding section of the Highway between Parramatta and Penrith. The bypassed section was heritage-listed in 2014 as the best-preserved section of the 1818 alignment.

From the late 1960s to the early 1970s the highway was almost entirely realigned and constructed to three lanes, being deviated as necessary, between Kirkconnell and Glanmire. Ironically this included reinstatement of most of the parts of Major Mitchell's 1830 alignment which had been deviated in 1929 to ease gradients.

This work was extended eastward to Mount Lambie in stages during the late 1980s and early 1990s. A second Cox's River deviation, to replace the 1929 deviation, was completed in 1993, between Marrangaroo and Mount Lambie.

At Katoomba the highway was deviated in 1985 to travel along the eastern side of the railway station, whereas the original alignment crossed the railway via a level crossing at the north end of Katoomba Street and ran along the western side of the railway. Immediately west of where the highway now crosses the railway due to this deviation, the highway was realigned over a distance of 1 km in 2004 to remove the sharp bend at 'Shell Corner'.

In Bathurst, the Denison Bridge (1870) was bypassed in 1991 by a realignment of the Highway where it crosses the Macquarie River into Bathurst city centre. Because of its heritage value it was retained for use by cyclists and pedestrians.

During 1991–1993 a massive cutting was made to improve and widen the alignment of the highway immediately east of Woodford. At the top of the southern side of this cutting can be seen the rudimentary excavation of the rock for Cox's 1815 road. This was severed in 1868 by the construction of the Springwood-Mount Victoria section of the Main Western Railway. The railway itself was deviated at this point in the 1920s when it was duplicated, and a cutting on the original alignment of the railway now forms the top section of the southern face of the highway cutting, the terrace in the face of the cutting being the bed of the original cutting.

In June 1993 the highway route was severed at Emu Plains with the closure to road traffic of the Knapsack Gully Viaduct. This occurred in conjunction with the westward extension of the M4 Motorway from its terminus since 1971 at Russell Street, Emu Plains. This extension connects directly to the highway at Lapstone, bypassing the viaduct. The portion of Great Western Highway west from Russell Street to Mitchells Pass Road is now only used by local traffic to access residential properties. Mitchells Pass, travelling is now one way eastbound between Lennox Bridge and the highway, due to its narrowness. Great Western Highway traffic therefore has to use the M4 between Russell St and Governors Drive.

A major realignment west from Mount Boyce (the highest point on the highway) to eliminate the Soldiers Pinch and other nearby sharp curves was completed in 2002.

Duplication and widening

From Railway Square to Woodville Road, the highway was widened to its present width when it was reconstructed in reinforced concrete in the 1930s. From Woodville Road west to The Northern Road the highway was widened, generally progressively westward, from the mid-1960s to the late 1970s. This section is a combination of six lanes with median strip, six lanes with wide landscaped median, and four lanes undivided. At The Northern Road in Kingswood the highway reverts to a four lane undivided configuration through Penrith shopping centre, widens to six lanes at the Castlereagh Road intersection, reverts to two lanes west from Castlereagh Road to Russell Street, and is then four lanes undivided with sealed shoulders from Russell Street to the base of Mitchells Pass, where it has been truncated.

Between 1981 and 2015 the NSW Government Roads & Maritime Services duplicated the highway between and west of Katoomba, generally working westward. This work incorporated the dual carriageway Springwood bypass, opened in 1967.

West of Katoomba, there is a further of dual carriageway on the River Lett Hill, and of dual carriageway from Magpie Hollow Road at Old Bowenfels to Lidsdale State Forest. This was completed as follows:

road widening and realignment completed in 2006
River Lett Hill 2014/15
Old Bowenfels to Bowenfels completed in sections during the late 1990s
Bowenfels to Marrangaroo Creek mid-1970s
Marrangaroo interchange with the Castlereagh Highway 1970
Marrangaroo interchange to Lidsdale State Forest (second Cox's River deviation) 1993.

Four-lane undivided sections are the of Victoria Pass (except for Mitchell's 1832 causeway, which is two lanes), and from Boyd Street in to the terminus of the highway at its junction with the Mitchell and Mid Western Highways in West Bathurst (parts have a raised median strip).

From Lidsdale State Forest as far west as Glanmire most of the highway is three lanes, with almost continuous overtaking lanes alternating between eastbound and westbound.

Controversy

Many people, including Aboriginal communities, are complaining about the expansion works. The completed highway will destroy a lot of native lands. There are also fears that the highway could wipe out platypus populations.

Current projects

Repairs and enhancements from Victoria Pass to Lithgow. The bridge at Victoria Pass is being refurbished and kept as two lane (one each direction.)
Forty Bends upgrade (from top of River Lett Hill to Magpie Hollow Road) – consists of extension of the length of three-lane pavement and measures to reduce the incidence of black ice in winter
Duplication from Ashworth Drive to Stockland Drive Kelso (in Bathurst). When M4 East opened between Strathfield and Haberfield in July 2019, route M4 was rerouted onto the new motorway. As a result, the section of Great Western Highway/Parramatta Road between Strathfield and Haberfield was designated A44, replacing the previous A4 designation.

Former route numbers

Great Western Highway has many former route allocations, including former National Route 32. Where and when the former route numbers were implemented are stated below.

Chippendale – Summer Hill:

National Route 31
Metroad 4
National Route 32
Metroad 5
State Route 31
A22

Summer Hill – Haberfield:

National Route 32
Metroad 4
unallocated:

Haberfield – North Strathfield:

National Route 32
Metroad 4
A4
A44

North Strathfield – Auburn:

National Route 32
State Route 44
A44

Auburn – Clyde:

National Route 32
State Route 44
A44

Clyde – Granville:

National Route 32
State Route 44
A44

Granville – Mays Hill:

National Route 32
State Route 44
A44

Mays Hill – Prospect:

National Route 32
State Route 44
A44

Prospect – Eastern Creek:

National Route 32
State Route 44
A44

Eastern Creek – Emu Plains:

National Route 32
unallocated:
State Route 44
A44

Emu Plains – Lapstone :

National Route 32
Metroad 4
M4

Lapstone – Bathurst:

National Route 32
A32