Our results show that roadway functional class, routes, traffic flow, types of roadway section, speed limit, traffic control device, functioning of traffic control device, lighting condition, roadway alignment and roadway profile are important determinants that engineers can target to reduce hit-and-run in fatal crashes.
14 Crash-level variables included day of the week, time of day, light conditions, weather conditions, roadway function class at the crash site, urban versus rural crash locale, traffic control devices present, and whether or not the crash occurred at an intersection.
Using ArcGIS 10.1 with Street MapTM North America (ESRI, Redlands, CA), aerial photographs, and internet resources, we geocoded locations of each reported residential address and calculated distance to the nearest major roadway (U.S. Census class A1 or A2).
In our study, fewer than 10% of the sample locations were within 200 m of a Class 1 roadway and fewer than 5% were within 100 m.
Also, the inclusion of two Class 3 roadway length variables in the same model is problematic due to their strong positive correlation (ρ = 0.72).
In these models, we did not find significant interactions by season, with the exception of the effect estimates for Class 1 roadways and for the terminal effect.
The effect estimate for Class 1 roadways was less stable at smaller sample sizes, likely due to the low density of Class 1 roadways across our study domain, implying that a relatively small proportion of our sampled sites contribute to the estimation of the effect of these roadways.
We additionally evaluated the effect of session-specific meteorology on the associations with local traffic sources by repeating the model-building procedure using the wind-weighted class-specific roadway length variables (200 m buffers).
However, these buffer-defined variables can limit the fraction of sampling points that contribute to parameter estimation where there is heterogeneity in source distribution at sub-domain scales (e.g., Class 1 roadways in our domain).
Soil erosion alongside roadways of various classes is impacted jointly by historical policy, distance to roadways, and landscape.
