Safety Processes
Our Customer Success team helps agencies turn crash data into actionable insights. The processes below show how they’re making their communities safer.
Using Optimal Fit SPFs
The Ohio Department of Transportation worked with AASHTOWare Safety to generate more specific SPFs to run network screenings based on predictive metrics and to help reach their safety goals, such as reducing the number of fatal and serious injury crashes.
Implementation Effort
- Requires minimal effort
- Timeline between 2-3 weeks*
* Assuming an agency has an existing, configured AASHTOWare Safety instance and all required data
Required Data
- Crash Data
Focus Areas
- Safety Performance Functions
- Network Screening
Process Overview
The Ohio Department of Transportation (ODOT) partnered with AASHTOWare Safety to create custom, state-specific SPFs using the Optimal Fit feature, allowing ODOT to conduct network screenings based on predictive metrics and see results statewide. After working closely with the AASHTOWare Safety team to set up Ohio’s crash and roadway data in the system, ODOT then identified the segment and intersection characteristics to be used for SPF creation. Special effort was placed on ensuring these groups accurately represent the various location types across the state.
Intersections were grouped based on the following criteria:
- Rural, Urban, Suburban
- Divided/Undivided
- Control Type
- Number of Legs
Segments were grouped based on the following criteria:
- Rural, Urban, Suburban
- Divided/Undivided
- Freeway/Non-Freeway
- Number of Lanes
- One-way/Both Directions
In addition to roadway characteristics, SPF groupings were made based on crash attributes, allowing ODOT users to target only the specific crashes they want to consider in network screenings. For example, this allows them to remove crashes, such as work zone, non-injury, and animal-related crashes.
Users can filter the following crash types to generate SPFs:
- All Crashes
- All Fatal and Injury Crashes
After completing this work, ODOT was able to generate meaningful SPFs in AASHTOWare Safety, using the Optimal Fit feature within Predictive Analysis.
AASHTOWare Safety’s Optimal Fit feature analyzes the crash history for each segment and intersection grouping and generates a custom SPF that represents the crash population for all segments on that roadway. By minimizing the average error between annual crash rates for each segment, the Optimal Fit function ensures an accurate SPF that represents the unique crash characteristics of each segment and intersection grouping.
ODOT utilized the FHWA resource center and SPF-R to validate the SPFs generated by AASHTOWare Safety’s Optimal Fit. This validation process proved that Ohio could use AASHTOWare Safety’s SPFs with full confidence in their processes.
ODOT uses these SPFs to conduct network screenings in the various AASHTOWare Safety Network Screening applications, allowing them to quickly locate the sites where their efforts can have the greatest impact and make the most of the available funding.
Using network screening to identify study locations allowed the ODOT team to diagnose safety issues, select appropriate countermeasures, and conduct economic appraisals. For example, based on FHWA guidelines and Ohio-specific before/after data, ODOT knows roundabouts are an effective countermeasure to prevent certain crash types in specific areas.
Based on this information, ODOT conducted a network screening to identify ideal candidates for roundabouts and encourage these areas to submit funding proposals. Thanks to this effort, about 83 roundabout projects were funded through HSIP between August 2022 and September 2024.
A big priority for ODOT was reducing the number of fatal and injury crashes on its roads. Investing in these roundabout projects helped achieve an immediate and long-term impact in mitigating fatal and injury crashes in these areas.
“Ohio DOT has embedded predictive analysis into almost every step of our roadway safety management process, from network screening through project prioritization. We’re leveraging AASHTOWare Safety to complete or assist in most steps, primarily network screening, but we’ll be expanding in the next few years. We’re starting to customize network screening methods to screen for locations that would be ideal for specific countermeasures, like roundabouts, and we’re also looking into what other countermeasures we can focus in on and screen for as well.”
– Brenton Bogard, HSIP Reporter, Crash Data System Manager for the Ohio Department of Transportation
More information on this topic can be found below: