The Art & Science of Vulnerable Road User Safety Assessments: How to Let Both Data and People Speak

Though FHWA was clear in what they wanted to see documented in a report, they left flexibility regarding how to go about the assessment, providing the opportunity (and challenge) for each state to determine their methodology. As with so much of the work we do in this profession, the VRU safety assessment needed to be both a science and an art: driven by objective data while relying on human-provided history and context to develop recommendations tailored for each place.

This is just the kind of challenge we enjoy, and we were excited to lead these assessments for the states of Maryland and Pennsylvania through on-call contracts with each state. Now that the projects are in the rearview mirror, we’re reflecting on how the process went, what we learned, and what may be useful to agencies looking to conduct similar assessments in the future.

Determining How to Conduct a VRU Safety Assessment

An effective approach to roadway infrastructure safety is a combination of spot specific and systemic improvements. Spot specific is what we typically associate with roadway safety. It is reactive, prioritizing where the most crashes have already occurred. Spot specific treatments tend to be more expensive, proportionate to the severity of crashes at one location. Think roundabouts, new traffic signals, or corridor realignments.

However, spot specific crashes are a fraction of the roadway fatalities on our roadway network. The remaining crashes are dispersed, often called one-off crashes, and difficult to address with spot specific treatments. Vulnerable road user safety improvements are often better served by the systemic approach due to the scattered nature of VRU crashes, especially outside of major urban areas.

A systemic approach to safety means reducing traffic injuries and fatalities by being proactive, targeting the facilities with the most crash risk rather than waiting for crashes to happen. The need to be holistic and proactive about safety has become more widely recognized since USDOT adopted the Safe System Approach, which focuses on building multiple layers of protection to prevent crashes from happening.

Here’s how this multi-pronged approach played out in the VRU safety assessments we conducted in Maryland and Pennsylvania.

Spot Specific

Our spot specific approach with both the Pennsylvania Department of Transportation (PennDOT) and Maryland State Highway Administration (SHA) was an approach inspired by a network screening tool that Kittelson’s software team previously developed for Stanislaus County, CA. The tool examines crashes on a roadway segment or intersection and identifies zones with high concentrations of fatal or severe crashes (also known as killed or serious injury crashes, or KSIs).

One early decision we needed to make with the analysis was how to approach measuring segments and how long each segment should be. We used a “sliding window” approach in which we defined a consistent segment length and “slid” it across identified areas of need throughout the state to locate the windows with major VRU safety concerns.

In both states, we measured equity factors (considering youth, older adults, women, racial minorities, ethnic minorities, people born outside the US, people with limited English proficiency, disabled people, and low-income populations as indicators of potential disadvantage) and short trip opportunity areas (areas where people would be more likely to make walking or biking trips if the connections were better or risk was lower). Each of these metrics translated to a score that added up to indicate which areas were in greatest need of attention. Nearly 200 high-risk areas for walking and biking were identified in Pennsylvania, and 132 in Maryland.

In Maryland, our approach was strongly informed by the state’s Pedestrian Safety Action Plan. Following their lead, we also factored community input into the equation to shape the “areas of need,” reaching out to all counties, transit agencies, metropolitan planning organizations, walking/bicycling advocacy organizations, and towns and cities with identified high-risk areas to collect more detail about safety concerns. Getting this on-the-ground experience, as it always does, provided nuance that can’t be seen in the data; for example, through engaging with transit agencies, we were able to make new connections about safety near transit stops, and added that into our process.

Systemic Safety

Our systemic approach varied by state. Here we’ll highlight what it looked like in Pennsylvania, since this was one of Pennsylvania’s first statewide systemic assessments.

We started from the ground up with FHWA’s systemic project selection tool. Given the ultimate goal of this assessment is to reduce fatal and severe injuries on the Commonwealth’s roadways, the systemic safety assessment sought to identify where there is a plurality of those crashes on the roadway network.

From the beginning, it was important for the results to be useful to those would implement the findings, which in this case is primarily PennDOT engineering districts and municipalities. As road owners, they have the power to change their right-of-way, so the initial risk factors we identified were related to infrastructure. Many of these risk factors overlapped with risks identified by Vision Zero efforts nationally and within the state, including high speeds, high traffic volumes, intersection skew, and complexity. Through our consultation meetings with MPOs, municipalities, transit agencies, bike/ped groups, and others, we also considered proximity to schools and transit.

Overlaying all of these risk factors on top of existing crash histories where available, we were able to identify and rank the highest risk segments and intersections for each county in Pennsylvania to pursue systemic improvements. This work lowered a barrier for systemic project implementation throughout the state.

Recommended Improvements

From these data analysis efforts, we summarized the spot-specific and systemic safety recommendations into a program of projects and strategies, or a “toolkit” encompassing infrastructure enhancements and strategic approaches to safety, equipping PennDOT and SHA with a range of solutions to bolster pedestrian and cyclist safety across their states.

While every state has now completed the federally-mandated VRU safety assessment, we believe this process has potential to be replicated at either the state or local jurisdiction level to help communities uncover specific projects that can be advanced to implementation.

What’s Next in Maryland and Pennsylvania

Now that every state has completed the assessment, what remains to be seen is how they’ll translate the findings into projects—which is the reason for doing the analysis in the first place! SHA is taking the high-risk areas identified in the assessment and feeding them directly into their transportation improvement program. With nearly $100 million programmed for pedestrian safety projects statewide, Maryland is poised to make meaningful progress.

In Pennsylvania, we’ve been able to use information from the assessment to inform Safe Streets for All (SS4A) action plans, as well as replicating the methodology at the local level to provide more detailed recommendations in those areas.

3 Lessons to Apply to Future VRU Safety Assessments

So, what are our takeaways now that the assessments have wrapped up? Here are three lessons the project highlighted for us:

1. The quality and reliability of the analysis heavily depends on the quality of the data used. If the data is incomplete, inaccurate, or biased, then the results will likely be flawed or imprecise. To achieve robust and targeted results, it’s essential your data inputs are of high quality, relevant, and suitable for the analysis being conducted.

2. On the other hand, in many situations, you may not have access to all the data you desire or think you need. Learn to work with the data that’s available, even if it’s not perfect or doesn’t cover all aspects you’d ideally like to analyze. Rather than waiting for perfect data, it’s crucial to make the best use of the data you do have by understanding its limitations and figuring out how to derive insights or make decisions based on it. This involves being resourceful and adaptable in your analysis approach.

3. The assessment is a means to implementation, not an end in itself. Go into it knowing what you can realistically implement and let that shape your approach. For example, a state with substantial HSIP funding can focus on allocating those funds to VRU safety, or local jurisdictions with safety action plans can seek SS4A implementation funding. After all, the goal of these planning and analysis processes is to build something that saves lives.

Continue the Conversation

When it comes to vulnerable road user safety, it’s an “all of the above” approach that will move the needle. We’ve seen this in other countries who have been successful in reducing pedestrian and bicyclist fatalities. An effective safety analysis is a science and an art, bringing together quantitative and qualitative pieces of the equation to piece together a plan built both on strong data and human experience, which includes considering missed opportunities. After all, as the Safe System Approach highlights, humans make mistakes. Our solutions must be as dynamic as the people who will be using them.

If you’d like to talk about this project further, don’t hesitate to reach out!