AustRoads Design Guidelines 

Austroads Design Guidelines explicitly specify that vegetation on the central island must not prevent an approaching driver from seeing oncoming vehicles. It specifies a sight distance triangle which should not be visually obstructed by any means.

As such it is always an issue that can be easily rectified. Consequences of not rectifying this easy issue is far greater. All vegetation on central islands must not be a type that grows above drivers’ eye levels measured from a passenger car. Road authorities must also ensure vegetation is regularly maintained to prevent this issue from occurring.

Aside from this, there must treatments in place to reduce approaching speeds of vehicles at roundabouts. These include reverse curves, rumble strips, street signage, flashing signs etc.