Date of Award
Doctor of Philosophy (PhD)
Wayne A Sarasua
Jennifer H Ogle
William J Davis
This research focused on evaluating how crash geocoding has improved over the years and how this enhanced spatial accuracy of crashes can potentially lead to a new paradigm for midblock crash safety analysis. Robust midblock safety analysis exhibits special challenges because methods of locating crashes have historically not been very accurate. One objective of this research was to assess how the accuracy of crashes has improved over time and what the current state of the art is.
The second objective focused on using segment lengths less than the Highway Safety Manual (HSM) recommended minimum of 0.1 miles for statewide screening of midblock crash locations to identify site specific locations with high crash incidence through a peak search methodology. The research clearly indicates that the use of segments of 0.1 miles (or greater) in many instances’ “hides” the severity of a single location if the rest of the segment has few or no additional crashes. The research also evaluated a sliding window approach using short segments. Based on the analysis, the short segment peak search method is recommended for use by state agencies as a network screening approach because it is much less complex to implement than the sliding window approach, locations can be easily ranked, and direct comparisons can be made of segment crash incidence over multiple years.
The final objective of this research was to compare the short segment peak search approach to other HSM methods. The results of the comparison revealed similar results at the highest priority level and thus the former can be used as an alternative in case of insufficient data on driveway and roadway characteristics.
This research shows that improvements in crash geocoding makes short-segment peak search network screening viable for segment lengths less than 0.1 miles. By using short segment network screening, segments of high crash incidence can be displayed with overlayed crashes at their actual crash locations which can minimize the need for developing collision diagrams. Secondly, one of the hypotheses is that the current intersection to intersection process aggregates crashes to long segments which can mask the crash severity of point locations.
Iqbal, Adika, "Midblock Crash Analysis Using Short Segments and Precisely Geocoded Crashes" (2019). All Dissertations. 2506.