SPEED
Map 1. Winter weather effect on speed-related collisions (2011) Winter weather colllisions, as % of total collisions Median = 6.9%
Collisions involving drivers speeding too fast for weather coniditions, as % of total collisions Median = 4.5%
Speed collisions, as % of total collisions Median = 9.5% Below median Above median Source: Indiana State Police Note: Winter weather collisions include as collisions occurring in snow, sleet/hail/freezing rain, or blowing sand/soil/snow.
Understanding the spatial distribution of traffic collisions and injuries can assist law enforcement and elected officials in developing policies and programs, while targeting resources to address the many issues that contribute to the frequency and severity of crashes. A variety of factors may influence the num- ber and nature of traffic collisions that occur in a given area, including the size and makeup of the population, the number of registered vehicles and licensed drivers, and the number of vehicle miles travelled (VMT). The following choroplethand density gridmaps show counties with the highest collision and injury rates in Indiana in 2011 by a select group of crash charac- teristics. Additionally, Indiana counties are ranked on a variety of collision metrics to determine which counties experienced the highest collision and injury rates in 2011. The economic costs associated with 2011 collisions are also reported for each county.
Notes:
All density grid maps were created using a ten-mile search radius.
Choropleth maps show counties grouped by quartiles.
Collision severity and injuries
In 2011, 188,132 collisions occurred in Indiana, 674 of which were fatal. The mean number of collisions per county was 2,045, and the mean number of fatal collisions per county was 7. Marion County ranked highest in the total number of colli- sions (27,426), and Warren County ranked highest in the per- centage of all collisions that were fatal (1.9), followed by Rush County (1.6). The median county rate of collisions per 100m VMT was 225.1, and the mean county rate per 100m VMT was 229.7. Tippecanoe County had the highest rate of collisions per 100m VMT (488.8), and Benton County had the lowest (80.4).
The total number of individuals involved in 2011 Indiana colli- sions was 303,528, and the mean number of individuals involved in collisions per county was 3,299. Marion County had the largest number of individuals involved (48,200) and the largest number of traffic fatalities (85), but ranked 74th out of 92 counties in the percentage of all injuries that were fatal.
Counties with the highest traffic fatality rates included Warren, Daviess, Benton, and Rush.
Speed-related collisions
Speed-related collisions accounted for 9.3 percent of all Indiana collisions in 2011, and 19.4 percent of all fatal collisions. The mean number of speed-related collisions per county was 190.
LaGrange County ranked first in the percentage of all collisions that were speed-related (17.8 percent). The median percent of speed-related collisions by county was 9.5, and the mean per- cent was 9.6. Many counties with the highest percentages of speed-related collisions were clustered in northern portions of the state.
Collisions involving alchol-impaired drivers
Collisions that involved an alcohol-impaired driver accounted for 2.6 percent of all Indiana collisions in 2011, and 18.5 percent of all fatal collisions. The mean number of alcohol-impaired
collisions per county was 54, and the mean number of fatal alcohol-impaired collisions per county was 1. The median per- cent of alcohol-impaired collisions by county was 2.6. Vermillion County had the highest percentage of collisions that involved an alcohol-impaired driver (4.6 percent), and Ohio County had the lowest (0.5 percent). The southwestern region of Indiana had more counties with high percentages of alcohol-impaired collisions than other areas in the state.
Collisions involving deer
A large percentage of collisions in rural counties throughout the state involved a deer. Counties with the highest percentage of deer-involved collisions were clustered in the northern and southern regions of the state. Counties located in the east cen- tral portions of Indiana have lower percentages of deer- involved collisions than other areas of the state. Pulaski County had the highest percentage of deer-involved collisions (55.6 percent).
Work zone collisions
There were 4,309 work zone collisions in Indiana in 2011. The median county rate of work zone collisions per 1,000 total colli- sions was 10.6, and the mean rate of work zone collisions was 13.2. Hancock County, located in central Indiana, had the high- est rate of work zone collisions (83.9 per 1,000 collisions). A number of other counties along the I-70 corridor across the state also were among the highest work zone collision rates in 2011. It is worth noting that work zone locations are constantly changing throughout the state, a fact that will likely impact which counties have the highest work zone collision rates in any given year. Counties with higher levels of road construction are likely to experience higher rates of work zone collisions.
Restraint use
Forty-four percent of vehicle occupants killed in Indiana colli- sions were unrestrained in 2011, while 9.2 percent of individu- als suffering non-incapacitating injuries were unrestrained. The median county percent of unrestrained individuals involved in collisions was 3.2 percent, and the mean county percent was 3.3. Daviess and Switzerland counties had the highest rates of unrestrained vehicle occupants at 8.9 percent and 6.9 percent, respectively. Urban counties throughout the state had some of the lowest rates of unrestrained injuries.
Young drivers
In 2011, 40,537 young drivers (aged 15 to 20) were involved in collisions (14 percent of all persons involved), of whom 55 suf- fered fatal injuries, 4,424 incurredpersonal injuries, and 36,058 were reported as other injury types or no injuries. On average, 15 percent of persons involved in collisions in Indiana counties were young drivers; the smallest proportion was reported in Pulaski County (9.9 percent) and the largest in Franklin County (21.2 percent). The median county rate of young driver involve- ment in collisions was 72.4 per 1,000 licensed young drivers, and the mean county rate was 75.2. Tippecanoe County had the highest rate of young driver involvement in collisions (161.1).