The 12 included studies: study methods and population sizes
| Study ID | Location | Method | Sample size | |
|---|---|---|---|---|
| Before/case | After/control | |||
| *Before/after road side observation or interrupted times series method. | ||||
| Cote, 1992 | Maryland, US | Non-equivalent control group | 51 | 379 |
| Cameron, 1994 | Melbourne, Australia | Before/after* | 3709 | 2477 |
| Ni, 1997 | Oregon, US | Before/after | 2168 | 2140 |
| Foss, 2000 | British Columbia, Canada | Before/after | 3950 | 4246 |
| Kanny, 2001 | Florida, US | Non-equivalent control group | 21313 | 450 |
| LeBlanc, 2002 | Novo Scotia, Canada | Before/after | 1494 | 672 |
| Thomas, 2002 | North Carolina, US | Before/after | 2448 | 1949 |
| Delamater, 2003 | Florida, US | Before/after | 1658 | 1029 |
| Liller, 2003 | Florida, US | Before/after | – | – |
| Parkin, 2003 | Toronto, Canada | Before/after | 1227 | 916 |
| Hagel, 2005 | Alberta, Canada | Before/after | 699 | 271 |
| Povey, 2005 | New Zealand | Before/after | 10646 | 5725 |