I travel this stretch of road every work day at some very early hours of the morning.
The coppers are frequently there on that bridge near the Buswood Tennis centre.
Makes for easy targets, as virtually everyone speeds along that stretch when there is little traffic.
The earliest I have seen them on the Bridge would have to be 4am with a Laser guns.
They will also follow you along Great Eastern highway in the wee hours of the morning heading to the airport in unmarked cars.
Funniest thing I have seen is a Riced up Lancer trying to race me that got nabbed.
Wish I could have seen the look on his face