This press release from the German manufacturer of speed cameras:
Western Australia police: Greater speed detection effectiveness using PoliScanspeed
(openPR) – Wiesbaden. Through deployment of PoliScanspeed, 58 percent more vehicles were detected exceeding the speed limit in Western Australia than in the previous twelve months. The Western Australia police force recently published these figures in its latest annual report for the year to 30 June 2011. “This performance is attributed to the improved effectiveness of new VITRONIC digital speed cameras”, the report states.
According to the report, 13.7 million vehicles were measured between July 2010 and June 2011. Of these 26.1 percent were detected travelling in excess of the speed limit. Over the previous four years, this proportion was consistently between 16.1 percent and 17 percent. These independently published results demonstrate that the Western Australia police have now joined a long list of PoliScan users who have reported outstanding performance results following introduction of the VITRONIC system.
These independently published figures also demonstrate that, as 26.1% are exceeding the posted speed limit, the speed limit is evidently set too low, not even including the 75th percentile of speeds. Speed limits are to be set to include the 85th percentile speed to minimise the incidence of crashes and to maximise road safety.
The report is in line with previous observations where the freeway speed limit includes only the 35th percentile. Do the arithmetic.
A single speed camera clocked more than 8000 motorists speeding in about 7 1/2 hours on the Kwinana Freeway this week, with close to 3000 fines expected to be issued because of the operation.
The new digital dual-lens camera was next to the Mill Point Road exit of the freeway monitoring southbound traffic for several hours on Monday and Tuesday.
Acting Assistant Commissioner Michelle Fyfe said yesterday that on Monday, between 8.50am and 11.30am, the camera had monitored 5588 vehicles and found that 3522 had exceeded the 80km/h speed limit.
On Tuesday, the camera measured the speed of 8759 vehicles between 8.50am and 1.35pm and found that 4791 were speeding.
Trying to comply with a speed limit that is way too low for the conditions is worse for road safety than compliance with an appropriate speed limit, based on including the 85th percentile of speeds under free-flowing, un-policed conditions.
contrary2belief 
The same thing happened out here in California. Years ago, our speed limits were 55 mph (sorry, too lazy to convert that to kph for you guys. I’m an American, remember 😛 ) but so few people obeyed that speed limit that it was eventually raised to 65 mph. Now, for the same reasons mentioned previously, there is talk of raising it to 70 mph! Montana is actually a U.S. State without a speed limit. Scary!