This project is being carried out jointly with Kelly Mara for the Land Transport Safety Authority. In recent years, speed cameras and compulsory breath testing have been introduced as road safety measures. The object is to see if we can identify any change in accident rates due to the safety measures or the reorganisation. Over the last few years there has been a gradual decline in serious and fatal accidents. In addition there appears to be an increasing traffic flow, at least on rural roads, possibly accelerating over the last year due to the economic upturn.
Good records are available on the fatal accidents.
Reporting rate on minor injury accidents is very low and we are not using this data. Detailed records on the use of speed cameras are available but there is less data on the effort being put into compulsory breath testing. We do not know of consistent detailed information on other safety campaigns. Somehow we have to separate the effect of the speed cameras and the compulsory breath testing from everything else. The main methods we are using include graphing a variety of breakdowns of the data, cusum charts and Poisson regression models.