December 5, 2018

Bicyclists and pedestrians are often classified as “vulnerable road users” due to the higher probability of serious injuries or fatalities when involved in a crash with a motor vehicle. In 2016, 16% of traffic fatalities involved pedestrians and 2.2% involved cyclists, compared to just 11% of all trips being taken by bike or walking. However, even these statistics don’t tell the whole story. Where are the trips being taken? How long are they? Who is making them? There is a severe lack of data on non-motorized trip-making, making safety analysis and prevention a particularly difficult task. While transportation planners often indicate the importance of safety, they must find the tools to measure it to be able to improve upon it, and finding or collecting the necessary data is an important first step.

Planners and engineers often address safety concerns through infrastructure treatments, such as adding or altering bicycle lanes and pedestrian crossings. However, with limited budgets and overwhelming transportation infrastructure needs, state departments of transportation (SDOTs), metropolitan planning organizations (MPOs), and cities must prioritize funding to best meet their goals.

Last month, researchers at the Georgia Institute of Technology published a study that examines how bicycle and pedestrian transportation planners prioritize safety treatment selection and location. Responses to a nation-wide survey with 133 responses provide decision-making behind pedestrian and bicycle safety treatments at local, regional, and state transportation agencies.

The study found that MPOs and SDOTs find safety to be highly important when choosing locations and types of bicycle and pedestrian safety treatments. However, many agencies are not able to effectively plan for safer bicycle and pedestrian infrastructure because they do not have the data or studies needed to prioritize treatment and site selection based on safety treatment effectiveness.

In order to calculate risk and assess treatment effectiveness of bike and pedestrian infrastructure, planners need both exposure and crash data. Exposure data that provide the raw counts of users at given location and enable risk calculations are severely lacking. Eighty-four percent of the respondents to the survey did not have any permanent sites for pedestrian counts, and eighty percent did not have any permanent bicycle count sites. While 23 respondents have over 100 permanent vehicle counting sites, none have more than 80 sites for cyclists, pedestrians, or combined bike/ped counts.

The lack of exposure data makes it impossible to prioritize site selection for safety treatments based on volume of users, but also eliminates the ability to calculate risk by looking at crashes in the context of exposure. Exposure counts are also necessary to assess use and safety once a treatment has been installed to compare before and after scenarios. Many treatments haven’t yet been show to actually increase safety, so understanding their effectiveness coupled with the travel behavior at high risk locations is important. Large increases in the volume of pedestrians or cyclists due to the perceived safety or comfort with infrastructure treatments that can provide a safety in numbers effect  – a variable that has been shown to increase safety.

While the majority of agencies who responded to the study survey do not have a robust bicycle and pedestrian safety program with consistent and good exposure data and safety data limited to police reports of crashes, there are agencies with large amounts of data and agencies actively and effectively utilizing the data available to them. Responses showed that sharing data between SDOTs and regional MPOs can help agencies gather bicycle, pedestrian, and vehicle volumes. Sharing data can cut down costs to produce studies and analyses that would be useful to both agencies, and SDOTS and MPOs may already use compatible data formats, which simplifies the process.

Overall, planners emphasized safety as a primary consideration in bicycle and pedestrian project prioritization, but without the data or studies in place to be able to assess treatments or locations for safety outcomes, how are they truly able to make decisions to improve safety? It is critical that data be collected and studies conducted to better understand the impacts of infrastructure on safety. The major step forward that agencies can take immediately is to find resources for data collection, data sharing, and before-and after studies in their own state, MPO or city to help the collective community better plan and build for bicyclists and pedestrians.