Tonkin Highway
Tonkin Highway is an north–south highway and partial freeway in Perth, Western Australia, linking Perth Airport and Kewdale with the city's north-eastern and south-eastern suburbs. As of April 2020, the northern terminus is at the interchange with Brand Highway and Great Northern Highway in Muchea, and the southern terminus is at Thomas Road in Oakford. It forms the entire length of State Route 4, and connects to several major roads. Besides Brand Highway and Great Northern Highway, it also connects to Reid Highway, Great Eastern Highway, Leach Highway, Roe Highway, and Albany Highway.
Planning for the route began in the 1950s, but the first segment between Wattle Grove and Cloverdale was not opened until 1980. Over the next five years, the highway was extended north to Great Eastern Highway and south to Albany Highway, and a discontinuous section was constructed north of the Swan River. In 1988 the Redcliffe Bridge linked these sections, and three years later, Reid Highway became the northern terminus. The next major works on the highway, between 2003 and 2005, extended the highway south to Thomas Road.
The central section of Tonkin Highway was upgraded to a six-lane freeway-standard road between 2013 and 2015, as part of the Gateway WA project to improve the wider road network around Perth Airport. From 2016 to 2020, construction commenced to upgrade the section of Tonkin Highway between Guildford Road and the original Reid Highway terminus to a six-lane freeway-standard road, and to build a four-lane freeway standard road up to Muchea, as part of the NorthLink WA project. The extension was originally known as the Perth Darwin National Highway. Planning provisions have been made for Tonkin Highway to be extended south of Byford in the future.
Route description
Tonkin Highway forms the entire length of State Route 4. It is a dual carriageway road maintained by Main Roads Western Australia, and subject to control of access along its entire length. Some junctions on the highway are at-grade and traffic light controlled; however, all junctions north of Hale Road in Wattle Grove and junctions with Albany Highway and Corfield Street in Gosnells, are freeway-standard with grade-separated interchanges. The central section of the highway between Reid Highway and Roe Highway is primarily six lanes wide; the remainder of the highway is primarily four lanes wide. The speed limit is near at-grade intersections, and along the stretches in between with north of Ellenbrook. A shared pedestrian and bicycle path is built alongside most of Tonkin Highway; namely between Muchea and Hale Road, as well as south of Mills Road East. In most other sections, the highway's sealed shoulders also function as bicycle lanes.Main Roads Western Australia monitors traffic volume across the state's road network, including several locations along Tonkin Highway. The section near Perth Airport, south of Great Eastern Highway, is the busiest, averaging over 56,000 vehicles per weekday in 2007–08, and over 57,000 in 2008–09. North of the Swan River, the traffic volume gradually decreased to under 40,000 vehicles per weekday near the northern terminus, in 2007–08. Measurements in 2008–09 showed the lowest volume to be under 10,000 vehicles per weekday near the southern terminus, north of Thomas Road.
In 2013, immediately preceding the upgrade of Tonkin Highway's central section to a six-lane freeway-standard road, junctions in and around Kewdale, Forrestfield and Perth Airport carried traffic volumes beyond their capacity during peak periods. Average peak period traffic speeds in this part of Tonkin Highway were measured as or less in 2013. The slowest section was from Leach Highway to Horrie Miller Drive, which recorded an average of during the afternoon peak period. Traffic volume, exceeding 50,000 vehicles per day in 2012, is forecast to almost double by 2031. Traffic modelling showed that leaving the current network of traffic light controlled intersections in place would have resulted in gridlock by 2021. Following the completion of the Gateway WA project in 2015, the upgraded road network is forecast to have an average speed in peak periods of between in 2021.
Muchea to Ellenbrook
Tonkin Highway commences at a roundabout interchange with Brand Highway and Great Northern Highway near the town of Muchea in the Shire of Chittering of the Wheatbelt region. The highway is a continuation of Great Northern Highway to/from the north of Western Australia with direction signage including Port Hedland some away. The interchange is characterised by both the installation of curvy green street lighting known as "wiggle poles" on both the bridge passing over the roundabout as well as on the westbound approach to the roundabout as well as a large road train assembly area to the southeast of the interchange.After, Tonkin Highway passes over the old Brand Highway connection between Muchea and Great Northern Highway before curving to the southwest to pass over Muchea South Road and the Midland railway line. The highway then enters the Perth metropolitan region and provides a western bypass of the town of Bullsbrook. The highway curves back to the south to pass over a roundabout interchange with Neaves Road. After, Tonkin Highway passes over another roundabout interchange with Stock Road West on the eastern side and Cooper Road on the west. A Heavy Vehicle Inspection Area is located immediately to the south.
After a further Tonkin Highway curves to the south-west, upon which the farmland that dominated the first section of the highway gives way to the more undulating and less fertile Bassendean dune system. The transition is marked by the presence of a fauna overpass crossing the highway. Just south of the overpass the highway starts skirting the western edge of the major suburb of Ellenbrook for the next.
Ellenbrook to the Swan River
Tonkin Highway then descends from the dunes to cross under a roundabout interchange with The Promenade to the east and Birralee Road to the west in Ellenbrook, after which it continues southwest and meets Gnangara Road at a parclo interchange. The highway then curves back to the south and passes between the suburbs of Cullacabardee and Whiteman, replacing a section of Beechboro Road North. The highway heads south to cross over Baal Street, after which another roundabout interchange is reached with Hepburn Avenue and the remainder of Beechboro Road North. Around south of the interchange the Ellenbrook line enters the median from the northeast, with both road and rail soon passing underneath Marshall Road. Tonkin Highway then arrives at a major free-flowing combination interchange with Reid Highway, previously the northern terminus of the highway. The wiggle pole street lighting reappears here, though the lights are yellow in colour this time. The highway then gains an additional lane and continues southwards, forming the border between the residential suburbs of Beechboro and Noranda; after, the highway enters the City of Bayswater LGA. The highway travels south for to both Benara Road and Noranda station, which Tonkin Highway passes under. The south-eastern corner of Noranda is south of the flyover, leaving the highway entirely within Morley. Tonkin Highway continues south through the residential area for, and reaches a roundabout interchange, with Morley Drive and Morley Drive East.Tonkin Highway continues southwards through a narrow S curve that realigns the highway further east. Partway through the curve, south of Morley Drive, the highway passes under Broun Avenue and Morley station, though there is no access between the roads. At this point the highway enters the north-eastern corner of, travels through it for, and then enters. The border between Embleton and Bayswater follows Beechboro Road, which is discontinuous either side of Tonkin Highway. The highway continues through Bayswater, between residential housing to the north-east and an industrial area to the south-west. After the S curve ends, with the highway now travelling between industrial and commercial properties. There is another interchange, this time a single-point urban interchange further south, with Collier Road. The Ellenbrook line deviates and exits to the southwest south of the interchange, with the highway forming collector-distributor lanes prior to the next major interchange with Guildford Road, further south. It is connected via a grade-separated interchange folded diamond interchange, with all the ramps located south of Guildford Road; to the north is the Midland railway line, and the parallel road Railway Parade, which the highway passes over. From here the highway turns south-easterly, perpendicular to the, and travels through another residential part of Bayswater for. Tonkin Highway crosses the river via the Mooro-Beeloo Bridge, which takes the highway into, in the City of Belmont LGA.
Perth Airport
A grade-separated interchange with Great Eastern Highway is located south-east of the Mooro-Beeloo Bridge. It is a parclo interchange, with the eastbound to southbound and westbound to northbound entry ramps looped. Previously, Great Eastern Highway's intersection with the southbound exit ramp also connected to Brearley Avenue which, until September 2018, provided one of the main access roads to Perth Airport's domestic terminal. However Brearley Avenue was closed to allow construction on the Redcliffe railway station. Beyond this interchange, Tonkin Highway, once again with three lanes, is within 's residential areas. A further takes the highway to the edge of the suburb of, where it becomes the border between Redcliffe to the south-west and Perth Airport to the north-east. later, the highway approaches the interchange with Dunreath Drive. Dunreath Drive replaced the Brearley Avenue entrance as the main access road from Tonkin Highway to Perth Airport's domestic terminal in 2015, it is a partial dogbone interchange, with the eastern side free-flowing while the western side controlled with a roundabout.After, the highway turns south, travelling in that direction for before reaching and curving back to the south-east, meeting Leach Highway and Airport Drive. Known as the Grand Gateway interchange, it is the primary access to Perth Airport's international terminal. It is a modified three-level combination interchange with two loop ramps. These movements, along with another five of the eight available between the three roads are free-flowing. Only Tonkin Highway north to Leach Highway west is controlled by traffic lights at the subsequent Leach Highway/Abernethy Road interchange before entering the highway itself to minimise the danger posed by weaving. The interchange is only high, its height limited by the airport runway to its north with tunnelling not possible due to the high water table in the vicinity. It is located at the borders between three suburbs: Cloverdale to the west, to the south, and the Perth Airport to the north-east.
Beyond Leach Highway, Tonkin Highway continues past industrial properties for, reaching the interchange with Kewdale Road to the south-west, and Horrie Miller Drive to the north-east. Now a single-point urban interchange, the initial signalised intersection was the original primary access road for Perth Airport's international terminals. Horrie Miller Drive now serves the industrial areas south of the terminal, and provides a secondary access to the terminals. After another, the highway reaches Abernethy Road. The only connections are a north-westbound looped exit ramp that merges with a local road, McDowell Street, north of Abernethy Road and a south-eastbound entrance ramp built in 2014. Beyond this intersection, the highway enters the City of Kalamunda LGA, and is the location of the border between the suburbs of Kewdale to the south-east and to the north-east. It continues along the border for, until it reaches Roe Highway, which marks the border between Kewdale and, on the south-western side of Tonkin Highway. Initially built as a signalised diamond interchange favouring Tonkin Highway, the Gateway WA project has since modified the connection into a hybrid diamond-stack interchange, with all Tonkin Highway southbound movements free-flowing, along with both left turns from Roe to Tonkin Highway.