FAQs

For any queries about Prinsep Road unrelated to the concept design please contact the City of Cockburn on 08 9411 3444 or [email protected].

The City does not allocate or manage speed limits, nor does the City have the authority to change a speed limit. 

Speed limits are guided by the Road Hierarchy for Western Australia Road Types and Criteria. Posted speed limits are determined and managed by Main Roads WA. 

Accordingly, the recommended operating speed of Local Distributor Roads such as Prinsep Road is 50 – 60km/h in built up areas and from 60 – 100km/h in non-built up areas. 

The City has put forward a request to Main Roads WA regarding a reduction of the speed limit on Prinsep Road to 50km/h. The outcome is subject to Main Roads discretion.

Main Roads WA (MRWA) provides the design guidelines and drawing for typical speed hump treatments. A Watts profile hump will be used. The speed humps are placed according to the Australian Standards (Austroads Guide to Traffic Engineering Practice) and MRWA guidelines.  

MRWA design considerations stipulate that where speed humps are used in series, hump spacing should ideally be between 80 and 100 metres with a maximum of 200m.

Some of the MRWA design principles to be adhered to for road humps to operate efficiently and safely are:

• The first hump should be within 50 metres of the start of the street where approach speed is low. If necessary, a treatment such as an entry statement may be provided to regulate approach speeds.
• Sight distance commensurate with an operating speed of 50 km/hr (or the prevailing speed zone in the street) should be available to approaching motorists.
• Humps should be constructed at right angles to the direction of travel.
• Where used in series, hump spacing should ideally be between 80 and 100 metres with a maximum of 200m.
• Humps should be clear of driveway entrances to avoid ground clearance problems when vehicles are accessing driveways.
• Piano markings on humps are to be located on the approach ramp and not on the road surface immediately before the ramp.
• The designer should ensure that the road drains efficiently.
• The portion of the hump on which the "piano" markings are to be applied, should be constructed from asphalt.

Street lighting is to be compliant with the Australian Standards.

Chicanes and blister islands have been considered however are not currently feasible for Prinsep Road for the following reasons:

• Treatments must be placed strategically to be effective, however underground services limit positioning options.
• Prinsep Road is a Local Distributor Road and therefore to be compliant blister islands would need to be designed for heavy vehicles, which makes them ineffective for the majority of road users (light vehicles).
• Blister islands would need to be installed either in conjunction with other calming devices such as speed humps or installed in high volumes, which may not be possible to do in an effective way (positioning constraints).
• Blister islands are not consistent with Local Area Traffic Management Policy recommendations for this section of road.