There is also a need to determine if the Roadway Safety Improvement (RSI) Projects completed from 1986 to 2000 have actually reduced accidents. Accident Reduction Factors (ARFs) are values used to determine the degree to which accidents decrease after an improvement project. A Severity Reduction Ratio (SRR) is a ratio of average accident severity before an improvement project to the average accident severity after an improvement project. A SRR of less than 1 indicates a reduction in the average severity of accidents following an improvement project. The SD1998-13 Project "Development of South Dakota Accident Reduction Factors" computed sixty-two ARFs and SRRs. However, it was decided that South Dakota should rely on reduction factors from other states to calculate benefit/cost ratios until the South Dakota Accident Reduction Factors are performed on a minimum of ten accident locations per type of improvement. Research is needed to review South Dakota RSI Project information to compare accident data for a three-year period before a project started to a three-year period after the project was completed. The resulting data can then be used to update Accident Reduction Factors and Severity Reduction Ratios for South Dakota by calculating the factors from at least ten accident locations for each type of improvement.
In 2000, the State Legislature raised the threshold for reportable accidents. Prior to that time, property- damage-only accidents generating $500 or more damage to an individuals property or accumulated property damage of $1,000 or more per accident were required to be reported. Since July 1, 2000, only those property-damage-only accidents generating $1,000 or more damage to an individuals property or accumulated property damage of $2,000 or more per accident are required to be reported. (Note: These changes do not affect the reporting of fatal and non-fatal injury accidents). RSI Project information needs to be updated and documented so that the data used to develop accident reduction factors remains consistent and can be used even though the reporting thresholds have changed.