Innovative Intersections Design Tool and Storymap Improve Safety

CHANGE

The Central Traffic and Safety division has created a new tool to help planners, region program managers and designers improve intersection safety and mobility at a minimum cost. Using a web application within the commonly used mapping program ArcGIS, the team created an Innovative Intersection Tool and Storymap (a storymap is a web application that combines context-useful information integrated with GIS maps). 

The Innovative Intersection Tool is intended to categorize intersection safety performance and provide innovative intersection type recommendations beyond standard stop-controlled and signal-controlled intersections. It provides information, including an estimated safety benefit, that allows engineers to look at the most applicable alternative intersection type for their specific location. This is important because it allows engineers to see recommendations that can guide their designs toward safer intersection types. The accompanying storymap has in-depth information on all innovative intersection types to educate engineers on alternative intersections that they might be unfamiliar with. Both links together help engineers select the safest and most cost effective intersection for their location, while ensuring they have all the knowledge necessary for implementation.

When creating the tool, the team leveraged the intersection calibration data and safety performance research from a recent BYU research study that evaluated over 1300 intersections comparing observed crashes to what would be expected based on the control type and volumes. Furthermore, all of these intersections were compared to various alternative control methods and an estimate of the safety benefit was determined for each intersection. This information is available to users as they select individual intersections in the tool.

RESULT

The Innovative Intersection Tool and Storymap provides users with more intersection design alternatives in a context-relevant format that is easily accessible and highly efficient. It allows region users to combine their local knowledge and experience with the resources of Central Traffic and Safety. Benefits to particular users include:

• Designers / Planners – will benefit by suggesting potentially more safe and fiscally responsible alternatives to their current scope

• Region administration – provide prioritized intersection locations for safety improvements

• Intersection Control Evaluation (ICE) program – automatically determines the safety benefit for innovative intersections, reducing the work of the preliminary studies for the ICE program 

• Traffic and Safety Personnel – helps answer the safety performance of intersections for data requests, data analysis, or public communication

UDOT’s Research UT-15.13 claims that a Continuous Flow Intersection reduces crashes by 12%. Additionally, research for different types of innovative intersections has shown that these intersections reduce fatal and injury crashes from 12-87% depending on which intersection type is installed. The safety benefit presented is the amount of money society saves from avoiding deaths and injuries by implementing any of the alternative intersections. The purpose of the innovative intersection storymap is to help UDOT make better decisions and to begin moving towards the goal of zero fatalities.

Consider the following: The innovative intersection storymap looks at 841 stop-controlled intersections with a range of 0 to 7.4 injury and fatal crashes per year. By installing one innovative intersection at a stop-controlled location, the average societal cost savings ranges between $350,000 to $3,500,000 (average of $2M). 783 signal-controlled intersections were evaluated ranging from 1.3 to 63 injury and fatal crashes per year. By installing one innovative intersection at a signal-controlled location, the average societal cost savings ranges between $2M -$10M (average of $6M).

If the Department installed one innovative intersection at a stop-controlled intersection each year, and one innovative intersection at a signal-controlled intersection every 5 years, the societal cost savings in reduced crashes would be on average about $3,200,000 per year.

Next Steps: The next step would be to expand the current database to include other intersection types. We are actively working to obtain cross-street volumes that will allow the analysis and recommendations to be applied to any intersection.