Are “Standards” Slowing Your Safety Efforts?

by Leah Shahum August 10, 2020 in News, Webinars

The Vision Zero Network was pleased to host a webinar on August 5, 2020 featuring Don Kostelec, a planner and advocate in transportation safety, health, and traffic engineering.

Image courtesy of Don Kostelec

There’s a lot of talk about “culture change” in the world of traffic safety. Oftentimes, people refer to changing the culture of the general public – the people traveling. And yes, that is a piece of the puzzle. But a more primary piece — and one that should be prioritized sooner — is changing the culture within our institutions that directly influence how people travel — safely or less so. For instance, is this roadway designed to encourage safety first? How about what speed limit is set? And what about the question of which road user — someone walking or someone driving — has priority at a tricky intersection that could pose dangers?

In this webinar, planner and advocate Don Kostelec shares examples of the many ways that key influencers in our traffic system — including planners and engineers — often have more flexibility to elevate safety than the traditional thinking may assume. And — if done right – this can be an important part of culture change toward Vision Zero.

The Dangerous Myth of 94%

We especially appreciated this example, shared by Kostelec, explaining how the 94% statistic is commonly cited and adhered to — incorrectly. Often promoted by public agencies — including the U.S. Department of Transportation and autonomous vehicle companies — this statistic claims, erroneously, that 94% of crashes in the U.S. are caused by human error.

Why is that a problem? First, this puts the vast amount of the burden of safety on individual road users, rather than the system in which those individuals are moving in, including the built environment, appropriate speed limits, and policies and regulations. This sends the message that the most effective way to improve safety is to somehow reach every individual on the road and convince them — individually — to make sure their behavior is perfect 100% of the time. Good luck with that!

Instead, we should focus greater energy on the upstream factors that influence individuals’ behaviors — the Safe Systems approach. For instance, if we know there are a troubling number of serious injury crashes at a specific intersection, we must find ways to re-design that intersection in order to change the behavior that’s causing problems. And, in another case, if we know that there is no way to separate road users (people walking, biking, driving) at a busy, multimodal location, then we need to lower the speed limit and add traffic calming to deter high, dangerous speeds, so that if there is a crash, it is not severe.

The second reason this 94% stat is so troubling is because it is inaccurate. In fact, research from the U.S. Department of Transportation’s National Highway Traffic Administration (NHTSA), developed in 2015, states that the 94% figure represents the last critical reason in a crash. As Kostelec shares, traffic crashes are more complex than one final decision — there are usually multiple factors (exs: poorly designed intersection, higher speed limit than merited, blocked site lines keeping a driver from seeing someone walking, etc.). In fact, the NHTSA research states explicitly that the 94% figure, “is not intended to be interpreted as the cause of the crash.”

Yet, still people cite this misinformation, including leaders at transportation agencies and traffic safety groups, which is then picked up and spread even further by the media. Should we be surprised, then, that there’s such a problem of victim-blaming in the U.S. traffic safety world? (Read more about the 94% Myth)

The Risks of Assuming Guidelines are Standards (It Matters)

Another key message Kostelec shared during the webinar is that misunderstanding of “standards” versus more flexible “guidelines” – especially when it comes up as part of the American Association of State Highway and Transportation Officials’ (AASHTO) Green Book. This contains resources for transportation officials that are intended to provide flexible guidelines for different agencies (How should speeds be set? How wide should a travel lane be? Where can we add a dedicated pedestrian crossing?), but their misinterpretation and misapplication can lead to the problem of, as Kostelec calls it, “highway worship.”

AASHTO’s Green Book actually states that federal, state, and local agencies may establish their own standards. But AASHTO’s guidelines are often misunderstood as inflexible standards for all agencies, sometimes blocking or stalling safety efforts. Many of these “standards” are merely recommendations or options for agencies, but they are believed to be mandatory, or at least, very difficult to get around. In reality, agencies may — and should — use independent design tailored to specific situations.

This misinterpretation of the all-mighty power of the Green Book has led to serious overbuilding and several troubling myths about road design and safety.

One myth Kostelec is working to debunk is the idea that there is a standard “Level of Service” requirement that means roadways must be aiming for free-flowing traffic with as few delays as possible. This can be a real challenge for making safety improvements, such as lowering speed limits or implementing traffic calming measures. In reality, there is no standard for the Level of Service at the national level.

Another myth is that lanes cannot be less than 12 feet wide on highways and arterial urban roads. In reality, there is a 9-12 foot range for highways and urban roads, and there is design flexibility. This matters because the extra space may be better used toward safety improvements, such as bikeways or wider sidewalks, etc.

Another myth Kostelec debunked is that agencies will be punished for not using AASHTO standards. In fact, exceptions to accepted design standards are permissible as long as they are accompanied by appropriate documentation. The reality is that AASHTO’s standards are flexible and should be adjusted to appropriately fit specific situations. And this can make a real difference in designing for Safe Systems and Vision Zero goals.

Image courtesy of Don Kostelec

The webinar covers many more examples and encourages a re-examination of some of the sources long considered golden calves of traffic safety. Culture change to advance Vision Zero will need to start with ensuring our own institutional and systemic cultures are recognizing what’s important and what’s possible for safety for all.

What can you do?

  • Community members and advocates: Get your own copy of the AASHTO Green Book & related guides, so that you can ensure decisionmakers in your community are planning for safety and not simply misinterpreting this language. Warning: These can be pricey, so encourage your local libraries or agencies to buy and share them. Or fundraise to get copies for your own organization.
  • Planners and engineers: If you don’t already have them, we encourage you to invest in copies of these documents.
  • Metropolitan Planning Organizations (MPOs): Adopt planning goals with clear references to these guidelines and don’t propel mistaken policies or funding strategies that interpret them as standards.
  • State DOTs: Be flexible with guidelines, modernize your state’s own design guides, and be careful not to misrepresent the AASHTO Green Book as a standard.
  • AASHTO: Take a more proactive role in helping people at the local, regional, and state levels understand the flexibility embedded in the Green Book and be a leader in safety over speed.
  • Everyone: Stop spreading the 94% myth and distracting from the fuller range of problems we can improve in our transportation systems.

Recent Posts


Recent Webinars


Newsletter Sign Up

Fields with a * are required.


Related News

World Day of Remembrance Draws Record Numbers & Calls for Change
From Boise to Boston, Durham to Denver, Omaha to Orlando, communities across North America mobilized for Safe Streets to Save Lives, as part of annual World Day of Remembrance for Road Traffic Victims on Sunday, November 20, 2022. A record number of communities across the U.S. — more than 60 — and hundreds more worldwide …

World Day of Remembrance Draws Record Numbers & Calls for Change Read More »

Build In Safety With the Safe System Approach: Examples from U.S. Communities
Too often, severe traffic crashes are seen as distinct tragedies that happen independently of each other. However, the reality is that these tragedies share common traits, are predictable, and can be prevented. The traffic deaths and serious injuries we hear about every day are largely the results of the current systems that normalize crashes and …

Build In Safety With the Safe System Approach: Examples from U.S. Communities Read More »

Vision Zero is Possible: Analysis Shows Path to Safe Mobility
More people – sons, daughters, grandparents, friends – were hit and killed while walking in the U.S. in 2021 than at any time in the past 40 years. Overall, roadway deaths reached a 16-year-high in 2021 in this nation. So far, 2022 is on the same tragic pace. But it doesn’t have to be this …

Vision Zero is Possible: Analysis Shows Path to Safe Mobility Read More »