Development of a temporary traffic management plan to help protect Bibra Lake’s vulnerable nesting turtles from road mortality has earned Cockburn Council endorsement.
A trial to reduce speed limits on Hope Road, Progress Drive and Bibra Drive by 10km/hr during the 2027 nesting season will now be developed, along with a cost estimate.
The Council will also take steps to clarify if a proposed Progress Drive turtle underpass project can be included in Main Roads WA (MRWA) funding of the Bibra Lake Urban Road Safety Program.
City of Cockburn Director of Sustainable Development and Safety Dan Arndt said the speed reduction trial would have broader safety benefits not only for turtles, but for road users in general.
“Data already available from the 2025 Turtle Monitoring Report, TurtleSAT citizen science app and City and community observations show local hotspots where female turtles are often killed due to vehicle strike as they cross busy roads in search of nesting grounds,” Mr Arndt said.
Roads planned for temporary speed reductions of 10km/hr during the September-December 2027 nesting season are:
- Progress Drive between Hope Road and Bibra Drive – 2.3km reduced to 40km/hr
- Hope Road between Progress Drive and Bibra Drive – 1.3km reduced to 50km/hr
- Bibra Drive between Progress Drive and Hope Road – 2.7km reduced to 50km/hr.
MRWA has notified the City that its approval for temporary speed reductions, signage and other traffic management measures is not needed on City-managed roads as part of a local government-approved Traffic Management Plan.
A report detailing trial outcomes, community feedback and a proposed way forward will be presented to Council for consideration following completion of the trial.
Funding to implement the temporary traffic plan will be considered as part of the 2027-28 budget process. Implementation of the trial, including public notification and traffic management, will cost about $75,000.
Mr Arndt said the separate turtle underpass proposal would be the first of its kind in the City if it came to fruition.
“It is proposed for the narrowest area of the Bibra Lake bank, between the northern retaining wall and Hope Road, allowing turtle access to nesting habitat in bushland west of Progress Drive without having to traverse busy parklands, shared paths and roads,” he said.
The latest Murdoch University Turtle Population Report received in March 2026 noted the underpass as a significant conservation opportunity for easy monitoring due to the high number of microchipped turtles in Bibra Lake from several years of capture and release research surveys.
The report noted that while the City’s turtle population persists, it remains vulnerable due to predation and road mortality.
At Bibra Lake, this had resulted in a male-dominated population and a low number of juveniles which is a concern for long-term population viability.
Mr Arndt said the City employed a multifaceted approach towards turtle conservation.
“These measures will complement the existing suite of actions that include volunteer nest protection, habitat restoration, and feral animal control.”