Length:

154 km (Pinjarra to Harvey: 52 km)

Termini:

Northern: Armadale Rd (SR14) and Albany Hwy (SR30), Armadale

Southern: Robertson Dr (NR1 / SR10) and Picton Rd (unnumbered), Glen Iris

Miscellaneous:

Continues as NR1 from Bunbury

Suburbs, Towns & Localities Along Route:

Blythewood, Coolup, Waroona, Hamel, Wagerup, Yarloop, Cookernup, Warawarrup and Harvey

Current: 20

Former: 1

Road Authority Internal Classification: ¹

H009

General Information:

State Route 20 is a north-south route connecting the southwestern suburbs of Perth with Western Australia's third largest city, Bunbury.

Once the primary thoroughfare connecting Perth to the southwest, this route links a multitude of small towns that owe their existence to the 19th-century construction of the railway line that closely parallels much of State Route 20's length.

The route is rural highway standard for most of it, and services residential, commercial, light industrial and agricultural areas.

1 July 1853: Colonial Secretary Frederick Barlee announced a new proposal for a Perth–Pinjarra–Bunbury route along the foothills of the Darling Scarp. ²

1864: Work commences on construction of the route announced in 1853 by two gangs of convicts.

1876: Construction completed of the route announced in 1853.

July 1941: The name South Western Highway officially adopted. ³

1980s: National Route 1 rerouted via Old Coast Road, SR20 introduced to the former NR1 alignment between Armadale and Bunbury.

2006: Additional passing lane added to the highway, south of Yarloop. ⁴

Pinjarra to Harvey

Entering Harvey:

Northbound as you enter the town of Harvey. July 2008.

Image © Paul Rands

Advance Directional Sign:

AD sign approaching Uduc and Weir Roads in Harvey. The town centre is bypassed by the highway. July 2008.

Image © Paul Rands

Reassurance Directional Sign:

Distance Sign as you leave Harvey. July 2008.

Image © Paul Rands

Entering Yarloop:

Entering the town of Yarloop near Johnston Road, July 2008.

Image © Paul Rands

Entering Waroona:

Sign announcing the town of Waroona, July 2008.

Image © Paul Rands

Waroona Town Centre:

Looking northbound through the Waroona townsite. July 2008.

Image © Paul Rands

Distance Sign:

RD sign as you leave Waroona, July 2008.

Image © Paul Rands

Entering Coolup:

Looking northbound as you enter the town of Coolup, July 2008.

Image © Paul Rands

Harvey to Pinjarra

Advance Directional Sign:

Advance directional sign at Harvey approaching Greenlands Rd, April 2016.

Image © Paul Rands

Entering Coolup:

Southbound at Coolup. December 2007.

Image © Paul Rands

Entering Waroona:

Southbound entering the town of Waroona near Patterson Road. December 2007.

Image © Paul Rands

Waroona Town Centre:

Southbound in Waroona. December 2007.

Image © Paul Rands

Waroona Town Centre:

Southbound in Waroona. December 2007.

Image © Paul Rands

Waroona Town Centre:

Southbound in Waroona. December 2007.

Image © Paul Rands

Distance Sign:

Southbound as you leave Waroona. December 2007.

Image © Paul Rands

Entering Australia's Southwest:

Southbound at Yarloop is this tourism sign indicating you've entered southwestern Australia, December 2007.

Image © Paul Rands

Entering Yarloop:

Southbound, entering the town of Yarloop, December 2007.

Image © Paul Rands

Local Radio Sign:

Southbound sign at Yarloop indicating which radio stations are receivable in the area, December 2007. This sign has since been removed.

Image © Paul Rands

Entering Harvey:

Southbound as you enter the town of Harvey, December 2007.

Image © Paul Rands

Entering Harvey:

Southbound as you enter the town of Harvey, April 2016. Click or tap here for a photo of this location by Paul Rands from December 2007.

Image © Paul Rands

Harvey River:

Southbound at Harvey as you approach the Harvey River, April 2016. Click or tap here for a photo of this location by Paul Rands from December 2007.

Image © Paul Rands

Approaching Weir Rd:

Southbound AD sign approaching Weir Road, Harvey. April 2016.

Image © Paul Rands

Distance Sign:

Southbound RD sign as you leave Harvey, April 2016.

Image © Paul Rands

Wellesley River:

South Western Hwy (SR20) as it crosses Wellesley River at Harvey, April 2016.

Image © Paul Rands