WA Radio Scanner Users' Group

Located Southbound just past the overpass to Leederville Station. The only thing I could think of, is something to do with the overhead LED board further down the Freeway?

There are two, one located either side of the freeway

Hi WF,

My guess is they are configured as height sensors for passing traffic. As there is an overheight vehicle sign just south of that position with warning signals attached.

Its most likely comprised of two sets of laser sensors (with an emitter and reflector on either side of the road) to eliminate items such as birds from incorrectly triggering the system when the laser beam is broken.

If this is the case, it is similar to the systems used in shops as doorway chimes/alerts and customer counters.



Geoff

From memory I think they are the measuring devices for the over height sign for the graham farmer tunnel going in the southern direction. I pretty sure there is also one as you are travelling west on the graham famer freeway just before the over height sign.

They are definitely over-height sensors that trigger the message board flashing lights. Last week there was a sign set up saying that were actually not functioning!

Hi Geoff, that sounds quite feasible!

Last week there was a sign set up saying that were actually not functioning!

Coming off the Narrow Bridge, its still not working as of yesterday.

Thanks everyone!

So if a vehicle is overhight, the orange lights above the board flash??? Or does the LED board light up as well?

Haven't seen those ones work but have seen others say "OVERHEIGHT"

Sensors, Sign board+Flashing lights. Southbound freeway.

Likewise on other entries.