National accident records and road description databases are used to calculate accident rates (expressed as the number of reported injury accidents per 100 million kilometres) for some selected types of road.
Rates were calculated for three classes of passing lane on rural sections of New Zealand state highways, and for rural unsealed sections of state highways and local roads. Where there was sufficient data, rates were also calculated for several traffic volume and terrain severity sub-categories.
While apparently sound indicative results were obtained in some cases, there was too much uncertainty in database matching of accident locations to allow confidence in many of the sub-category rates.
It is recommended that similar studies not be undertaken until database information is improved.
Keywords: accidents rates, passing lanes, unsealed roads, New Zealand