Before-After Rating Fields | |||
| Rating Inputs | Rating Outputs | ||
| Number of miles/sites of reference/comparison group for SPF estimation and trend analysis (for analysis based on "segments", number of miles should be used; for analysis based on intersections or similar units, sites should be used). | 50+ | Rating for number of miles/sites of reference/comparison group. | 10 |
| Exact number of miles/sites of reference/comparison group if known. | |||
| Number of crashes in reference/comparison sites for SPF estimation and trend analysis. | 1400 | ||
| Years of data in reference/comparison sites for SPF estimation and trend analysis. | 10 | Rating for number of crashes in reference/comparison group. | 10 |
| Reference/comparison group is appropriate to account for any spillover/crash migration | yes | Rating for spillover accounted for. | 5 |
| Number of miles/sites for treatment group (for analysis based on "segments", number of miles should be used; for analysis based on intersections or similar units, sites should be used). | 50+ | Rating for number of miles/sites of treatment group. | 10 |
| Exact number of miles/sites of treatment group if known. | |||
| Number of crashes in the before period, for treatment group. | 412 | ||
| Number of crashes in the after period, for treatment group. | 155 | ||
| Number of crashes expected in the after period, for treatment group. | Rating for crashes before plus expected after. | 10 | |
| At least one traffic volume count in the before period. | yes | ||
| At least one traffic volume count in the after period. | yes | Rating for at least one traffic volume count in before and after periods. | 10 |
| Possible bias due to RTM is addressed or the treatment was a systemwide implementation. | yes | Rating for RTM addressed. | 25 |
| Accounts for changes in traffic volume during the study period. | yes | Rating for changes in traffic volume accounted for. | 10 |
| Accounts for time trends and other changes during the study period. | yes | Rating for time trends/other changes accounted for. | 10 |
| Reference/comparison group is similar to treatment group in terms of AADT, i.e., the AADT range for the reference group overlaps the AADT range for the treatment group, and the mean AADT for the reference and treatment groups are similar to each other? | yes | Rating for reference/comparison and treatment similar AADT. | 10 |
| The reference/comparison group and treatment groups belong to the same roadway type (e.g., rural two lane roads) and site type (e.g., horizontal curve). In addition, the reference/comparison groups are similar to treatment group in terms of other important site characteristics? | yes | Rating for reference/comparison and treatment same roadway characteristics. | 10 |
| The SPFs were estimated using appropriate statistical procedures and functional form is reasonable? | yes | Rating for appropriate SPF. | 10 |
| CMF is statistically significant at 0.05, 0.10, or 0.15 levels. | 0.05 | Rating for CMF significance level. | 20 |
| RATING TOTAL | 150 | ||
Read more about how the Star Quality Rating scores are determined.
