Statistical and Spatial Analysis of Intersection Crashes in San Antonio, Texas
Road crashes are a leading cause of death and serious injuries in the US, and Texas is ranked No.1 in the country with the highest number of fatal crashes. Intersections are recognized as being among the most dangerous locations on the roads. On an annual basis, a cost of over $40 billion is associated with intersection crashes, which account for more than 20% of fatalities nationwide. Due to the limited resources available for road safety, it is important to identify high-risk intersections so that they can be prioritized for infrastructure improvement. This study used crash frequency and crash severity as the two essential approaches to understanding the relationship between crash occurrences at intersections and contributing factors. Crash data from 2013 to 2017 were used in the analysis. There are 73,755 intersection crashes in San Antonio during the period. Results from the detailed analysis show that different factors had varying effects on crash severity levels. Drivers' inattention and disregard for traffic control and signals are the major cause of most of the intersection crashes within the city. Generally, male drivers were involved in intersection crashes more than female drivers, even though we have more licensed female drivers than male. The predominant type of intersection crash was the angle crashes where vehicles involved are both going straight, while the one motor vehicle going straight type of crash has more occurrence in cases that involve fatal crashes.
The analysis further identified 52 intersections that had 100 crashes or more, and 36 intersections with a crash rate of greater than 1 crashes per million entering vehicles. The crash rate helps to determine the relative safety of an intersection compared to similar intersections. ArcGIS Spatial Analyst tool was used to identify the major high-risk intersections based on the volume of crashes within the city, and it revealed that we have major concentration around the central part of San Antonio (Downtown), the northeast and north-west side, and west side of San Antonio. There is a need for further studies on the high-crash number intersections identified to better understand challenges associated with each intersection and to develop effective countermeasures for reducing severe injuries and fatalities in San Antonio.