What the study found
The study found that horizontal curve realignment on rural two-lane roads was associated with lower crash counts. It reports reductions in total crashes, injury and fatal crashes, run-off-road and fixed object crashes, dark crashes, and wet crashes.
Why the authors say this matters
The authors say the evaluation was intended to assess the safety effectiveness of this strategy and to reduce lane departure crashes, especially run-off-road crashes. They also note that the findings add to comparisons with earlier cross-sectional studies and include an economic analysis.
What the researchers tested
The researchers evaluated crash modification factors, or CMFs, which are measures of how a roadway treatment is associated with crash changes. They used a before-after empirical Bayes method with data from rural two-lane roads in California, North Carolina, and Ohio, and compared the CMFs with published cross-sectional study results.
What worked and what didn't
The evaluation found statistically significant reductions at the 95% confidence level: 68% for total crashes, 74% for injury and fatal crashes, 78% for run-off-road and fixed object crashes, 42% for dark crashes, and 80% for wet crashes. The before-after CMFs were lower than CMFs from two previous cross-sectional studies, and the economic analysis reported a benefit-cost ratio of 3.17:1, with a range of 1.75:1 to 4.38:1.
What to keep in mind
The results apply to the site characteristics described in the abstract, including the range of curve changes, traffic levels, and segment lengths. The authors note the need for further research with a larger sample of sites to assess how reliable these CMFs are.
Key points
- Horizontal curve realignment was linked to fewer crashes on rural two-lane roads.
- Reported reductions included total crashes, injury and fatal crashes, run-off-road and fixed object crashes, dark crashes, and wet crashes.
- All reported reductions were statistically significant at the 95% confidence level.
- The before-after CMFs were lower than those from two earlier cross-sectional studies.
- The economic analysis reported a benefit-cost ratio of 3.17:1.
Disclosure
- Research title:
- Curve realignment reduced crashes on rural two-lane roads
- Authors:
- Raghavan Srinivasan, Daniel Carter, Craig Lyon, Matt Albee
- Institutions:
- University of North Carolina at Chapel Hill, University of North Carolina at Chapel Hill
- Publication date:
- 2026-04-21
- OpenAlex record:
- View
Get the weekly research newsletter
Stay current with peer-reviewed research without reading academic papers — one filtered digest, every Friday.