The effectiveness of the 3-feet legalised passing distance is examined in this study, and the answer is “yes”, in general terms. The study was made one year after the law was introduced, and no “before” data was included.
The study looks at 10.8 hours of video footage recording 586 vehicle passes collected during 34 trips and concludes that about 80% of cars leave more than three feet of space when overtaking a person riding a bicycle, 20% leave exactly three feet or marginally less. Nor surprisingly 5-feet wide marked bicycle lanes resulted in consistently safe passing distances.
Further interesting reading on the problematic of safe passing distance can be found in articles written by Marilyn Johnson at Monash University. She examined well over 100 hours of video footage and established that an on-road cyclist can expect a negative interaction with a car about every three hours, with the car driver being at fault in over 80% of incidents.
We have been asking for a safe one metre passing distance in WA for well over a year, and have repeatedly spoken to the Road Safety council about the need to make WA roads safe for people riding bicycles. We have also spoken to the RAC on the topic, but the RAC (who represent all road users on the Road Safety Council) are opposed to a legalised safe passing distance.