The Road Safety Crisis

April 1, 2024
How GIS can help America achieve Vision Zero’s goals

By Adam Carnow , Contributing Author

America faces an emergency, and the problem is our streets. The U.S. transportation network is getting more dangerous.

Since 2010, the number of pedestrians killed by drivers has increased more than 75%. The federal government is aware of the problem and is designating significant resources to address the crisis.

If we are going to be successful, we need to apply a geographic approach. There are proven best practices that we can learn from to increase the likeliness of success in this important battle.

With the creation of the National Roadway Safety Strategy, increasing transportation network safety is a top priority for the U.S. Department of Transportation (USDOT).

USDOT has authored an interactive online report, Our Nation’s Roadway Safety Crisis, to help the public understand this issue. The report provides data analyses and visualizations and information on the progress towards the Vision Zero goal.

Vision Zero is a global initiative used by agencies to provide a strategy to eliminate all traffic fatalities and severe injuries, while increasing safe, healthy, equitable mobility for all.

The Vision Zero strategy includes community input. It provides transparency and accountability by sharing the process and progress with the community.

Interactive surveys, web maps, dashboards, and open data sites provide an intuitive and easily accessible way to communicate and engage the community throughout the process.

The vision also includes the notion that traffic deaths are preventable, and the solution needs to use a multidisciplinary, systems approach. This approach prioritizes the use of data, and it addresses equity and incorporates community engagement.

For the next five years, there are multiple transportation safety project federal funding sources, including the Safe Streets and Roads for All (SS4A) and Rebuilding American Infrastructure with Sustainability and Equity (RAISE) grant programs.

To take advantage of this funding, organizations need to understand where the problem is in their community, identify appropriate mitigation measures, prioritize those projects in an equitable manner, and provide transparency and accountability via community engagement.

Making our transportation network safer is a spatial problem. Transportation fatalities and injuries occur at specific locations.

Spatial data and analysis are required to understand why these incidents are happening at these locations and to prioritize mitigation strategies.

Equity is also a spatial problem. As we address transportation safety, it is crucial that remedies are equitably applied across our communities by understanding where the disadvantaged are located and ensuring that their interests are considered.

A Geographic Information System (GIS) is designed to assist with solving spatial problems. GIS is a mission-critical, enterprise IT system that integrates all types of data, and it provides visualization, mapping, analysis, and modeling to better understand complex spatial problems. It also develops data-driven plans and strategies for better decision making.

GIS allows for advanced spatial analysis to better understand contributing factors around transportation safety incidents.

Traffic crash data is hard to visualize and analyze using traditional methods. Analyzing traffic crash data requires advanced methods and visualizations incorporating 3D and time.

A GIS-powered technique known as space time pattern mining delivers better understanding of traffic crash data over time.

Figures 1 and 2: In this visualization, the GIS has identified “hot spots” (statistically significant clusters of crashes) and classified them as new, consecutive, or sporadic, and symbolized them as hexagon stacks. These stacks show how the hot spot data changes over time. Each hexagon represents a month of data and the hexagons at the top of the stack are the most recent.

Figure 3: Another effective way of visualizing traffic crashes over time is using 3D ribbons in relation to road segments. In this example, each of the six layers of ribbons reflects a year of data, with 2010 on the bottom, and each subsequent year above. Lighter colored red ribbons are statistically significant but are less intense than darker red ribbons.

The objective of these spatial analyses and visualizations is to designate a community’s High Injury Network (HIN).

The goal of this exercise is to help prioritize transportation safety efforts by analyzing crash trends over at least five years that include severe injuries and fatalities.

Once the high injury network is identified, it is critically important to analyze who is being injured and killed by the crashes.

Research shows that traffic injuries and fatalities disproportionally impact disadvantaged communities. The location of these populations can be mapped, visualized, and analyzed with GIS.

Sociodemographic data can be used to identify populations based on a variety of factors. This allows for the application of an equity lens to the high injury network using a social vulnerability or equity index developed with GIS.

There are multiple data sets and tools provided by federal agencies to assist with this including the USDOT’s Historically Disadvantaged Communities and the Justice40 initiative.

The development and application of an equity index with GIS was pioneered at Tacoma, Wash. The index is built upon 32 key indicators within five categories: livability, education, environmental health, economy, and accessibility.

Indicators include such things as crime, home value, affordable housing, school quality, amount of green space, and access to recreation and transit.

The map and its underlying data give the city council guidance to see and repair the harm done by systemic racism. All city projects are now required to be analyzed with the equity index before they are eligible for funding.

Other technologies like artificial intelligence (AI) can be added to spatial analysis to yield additional insight.

Cobb County, Georgia used AI and GIS, known as GeoAI, to analyze multiple years of single vehicle fixed object crashes.

Their work found that the highest contributing factors to those crashes were slope and curvature of the road. They used this information to prioritize and focus transportation improvements in those areas to mitigate the risk.

The Americans with Disabilities (ADA) Act of 1990 requires the installation and maintenance of curb ramps designed to provide a safe and accessible route for all pedestrians at intersections. In Douglas County, Nebraska, GeoAI was used automate the identification of over 34,000 ramps in just 12 days, saving six months of staff time had they used traditional methods.

This GIS-powered approach to improving transportation safety has been proven through numerous success stories across the U.S.

Maps and GIS analysis helped transportation planners and engineers in Louisville prioritize roadway safety improvement projects by identifying high-risk corridors and vulnerabilities in communities. GIS analysis also helped Louisville earn a $21 million SS4A grant.

While most of the U.S. is dealing with rising traffic crash fatalities, Hoboken, N.J. has managed to solve this problem. As of November 2023, they have not experienced a single traffic death since January 2017.

Though Hoboken is about two square miles, it is densely populated with about 60,000 residents. Still, they represent one of the few victories that others can look to emulate.

One of the contributing factors to their success has been the use of the geographic approach to realizing safer streets. They have used GIS to support their entire Vision Zero initiative, from traffic crash data visualization and analysis to the prioritization of transportation safety improvement projects, grant applications, and community engagement.

It is of paramount importance that the U.S. works together to reverse the trend of increasing traffic injuries and fatalities.

Transportation safety and equity are spatial problems. GIS is the mission-critical, enterprise IT system designed to help solve spatial problems.

There are numerous resources available to help agencies apply the geographic approach. GIS can support the entire process toward realizing Vision Zero, the elimination of all traffic fatalities, and severe injuries:

  • Crash and High Injury Network Visualization and Analysis
  • Equity Analysis
  • Project Prioritization
  • Public Engagement, Transparency, Storytelling, Reporting
  • Obtaining and Justifying Funding

Most agencies in charge of improving transportation safety have established GIS programs. Vision Zero is a challenge, and it is time for America to unite and use technological advancements to help make this goal our reality. RB

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