Main Roads' Speed Zoning Policy and Application Guidelines, published in May 2020, adopted the replacement of Speed Buffer Zones with “Speed Limit AHEAD” signs. This allows the lowering of speed limits by greater than 30 km/h using repeated sets of “Speed Limit Ahead” signs.

Key Messages

• Speed Buffer Zones have been removed in the latest version of Australian Standards and have been replaced with “Speed Limit AHEAD” signs.

• The “Speed Limit AHEAD” signs replace the need for Speed Buffer Zones and achieve the same outcome by warning road users to slow down prior to a reduced posted speed limit.

• In WA, there will be two sets of “Speed Limit AHEAD” signs prior to any speed limit reduction which is more than 30km/h.  

• The use of “Speed Limit AHEAD” signs will bring Western Australia in line with the other states and territories across Australia.

When does it go live?

Since mid-2020, Main Roads has stopped implementing Speed Buffer Zones. Main Roads is not rolling out wholesale changes to existing Speed Buffer Zones, but is doing so gradually by working with the regions/local government when they seek review of, or changes to, speed limits. Some regional areas of WA are already utilising the “Speed Limit AHEAD” signs instead of “Speed Buffer Zone” signage.  

What is changing?

Previously, a short 300-400 metre Intermediate Speed Zone (e.g. An 80 km/h zone, where the speed was being reduced from 100km/hr to 60km/hr) would be used as a Speed Buffer Zone prior to any speed limit reduction which was more than 30km/h . Since mid-2020, this Intermediate Speed Zone is no longer required, and two sets of “Speed Limit AHEAD” signs (e.g. 60 AHEAD) would be installed instead.

Where are the changes occurring?

• The changes will continue to gradually occur state wide.

• Some Speed Buffer Zones have already been replaced by “Speed Limit AHEAD” signage. 

• The use of “Speed Limit AHEAD” signs is in harmonisation with other states and territories in Australia.

• The placement of “Speed Limit AHEAD” signs considers road conditions, and is typically at four to ten seconds of travel time from the change in speed limit.

What do I need to do differently?

When you see “Speed limit AHEAD” signs, you should prepare to reduce your speed to ensure you do not exceed the posted speed limit by the time you enter the new speed zone ahead.

Where will the speed limit be enforceable?

Speed limits are enforceable from the time a driver passes a speed limit sign, or from the time a driver enters a road which is subject to a default speed limit. The “Speed Limit AHEAD” signs are advisory signs pre warning drivers that a new speed limit is coming up ahead.