Thoughts

  • Dave

Principles for transportation safety in Atlanta

It’s the Fifth United Nations Global Road Safety Week, and this year’s theme is “#SpeakUp.” The theme is meant to call for leadership on road safety to save lives. Before coming back to school for my PhD, I worked a great deal with the United Nations Road Safety Collaboration. I loved that work, and I loved working with people around the world to make roads safer. However, I grew tired of the lack of progress here in the United States and specifically in Atlanta. One of the many reasons I decided to go back to school was to work on more local issues. Thus Global Road Safety Week is a good time to look at how we’re doing in Atlanta and #SpeakUp for safety. Keeping with that theme, I’ve read city policies and documents related to road safety, and will be posting some reactions and ideas to those documents this week. With so much excitement about a potential Atlanta Department of Transportation, the RENEW Atlanta project list, and generational opportunities to change Atlanta’s transportation system, I can think of a better time to #SpeakUp.



Much of the coverage about ADOT has rightfully focused on the nuts and bolts of what that department will consist of; consolidating different city departments, and streamlining projects. However, forming ADOT gives the city a rare opportunity to think about our transportation system and what our priorities are as a city. As ADOT forms, it is critical that it defines what sort of transportation system it intends to create. This is no small, or insignificant task. Most of our public space is roads. How we build our transportation network is effectively how we build our city.


Thus, defining the vision and mission of ADOT will be critical to Atlanta’s future. Fortunately, the City of Atlanta began working on Atlanta’s Transportation Plan years ago to operationalize the Atlanta City Design. Both those documents are admirable and worth reading. The Transportation Plan does a nice job laying out high level priorities, and specifically calls out safety, mobility, and affordability as the three primary goals for transportation projects. It’s a great document and worth the time to read.


Being that this is Global Road Safety Week and I’m a safety researcher, I was happy to see safety get top billing. It wasn’t entirely surprising as most organizations state that safety is one of their top priorities. DOTs are no different, but they don’t do a very good job of meeting those goals. Road traffic deaths are the number one killer of people ages 5-29 in the United States, after all. Atlanta frequently touts itself as “world-class,” but our record on traffic deaths is far from it. Compared to peer cities in the United States, Atlanta’s safety record is awful. According to the city’s Safer Streets Technical Memorandum, Atlanta has 3-3.7 times the crashes of peer cities. That is remarkable. Our record on pedestrian crashes is particularly dismal, with 1.7-3x the number of crashes as other cities.



Considering that safety is a major issue in Atlanta, we need to serious consider what we mean by safety and how we deliver safety in projects. Further, we need to consider how to communicate what we mean by safety. Recently, Vision Zero has become an increasingly popular policy in American cities. In fact, the Mayor also promised that Vision Zero is on the table in the city of Atlanta. This is a massive step in the right direction. However, it’s difficult to envision what that actually means in practice. Atlanta’s Safer Streets Technical document uses the oft-cited “5 E’s” to guide their “data-driven approach.”

  • Education-teach pedestrians, bicyclists, and drivers about safety

  • Enforcement-work with local law enforcement to issue citations at dangerous locations targeted at reducing dangerous behaviors

  • Engineering-create safe infrastructure for all users through design, operation, and maintenance

  • Evaluation-monitor strategies to confirm if they are working, or if adjustments are needed to met goals and objectives

  • Emergency medical services-when crashes occur, a quick response can save lives, the likelihood of preventing death is highest in the first hour after a traumatic injury


The 5 E’s are the primary traffic safety paradigm in the United States, and frankly, we haven’t done so well in terms. This stems from the fact that not all E’s are equal, and responsibility is dispersed across different entities. It’s easy to shift the blame to one of the different E’s when you’ve failed, and our infrastructure fails far too frequently, but we can always rely on the fact that someone will argue “if we just have more education and enforcement…” or something along those lines. ADOT should consider laying out more visionary principles that they can communicate easily, and use as guidance for all projects.


While the Dutch are frequently cited for their excellent cycling infrastructure, they don’t get enough credit for their remarkable progress in road safety. The Dutch approach is known as Sustainable Safety. Sustainable Safety is based on 5 core principles, listed below. I’ll describe each and note applications within the City of Atlanta:

  • Functionality of roads

Roads fall into one of three categories: through roads, distributor roads, and local access roads. The three categories are mutually exclusive and cannot be mixed. There is a clearly defined functional class system in the US, which consists of highways, principle and minor arterials, collectors, and local streets. So what’s the difference between our approach and theirs? First, having 3 classifications is easier to define and identify how they should interact. Having more classifications increases the likelihood for complexity when the roads interact. Intersections between local access roads and arterials tend to be unsafe and function poorly for all users (e.g. intersections on Dekalb Avenue and Memorial Drive). Also, the Dutch do not try to mix functions for roads. Here in the US, we frequently mix functions. A trip down Campbellton Road is instructive. It features many residential homes, but is built primarily as a means to travel through it. It thus fails as a street to live on, and serves people driving vehicles poorly as well. Chapter 3 of Streets Atlanta does well in identifying how we can delineate how our streets could function. It's a good start and we can do even better.

  • Homogeneity of speeds, direction, and mass

Injuries are caused by the differentials in force. Higher speed causes more crashes, but higher mass compounds the effect. Thus, space on roadways is designated by the potential transfer of energy. Most people are familiar with Dutch cycle paths, which are constructed along routes when speeds exceed about 20-25 mph. This is done to eliminate the mixing of high speed vehicles with lower speed cyclists. However, this relates to other design elements as well. If vehicles are traveling at high speeds in opposite directions, there should be physical medians between the directions. The same is true for transit (as a bus is much heavier than a passenger vehicle). If you expect the bus to operate at higher speeds, it should be located in its own space. Again, the city’s “Street Design Principles” do well to state that speed is an issue and that city streets should generally be designed for no more than 35 mph. However, we can do better than state that the speed limit should be lower. We should state that one of our core priorities is designing risk out of the system. Ensuring the homogeneity of forces is means of doing so.

  • Predictability of road design

Road design should be consistent and users should understand what type of road they are on, and thus how they should drive on it. This is similar to the concept of “driver expectancy” in American transportation engineering. We do this well on interstate highways. When you drive on a highway, you know it. We aren’t as effective in lower road classifications. Many “residential” streets look more like drag strips than places to live. The new street design guide again does well delineating how new streets and retrofits should be accomplished (Chapter 4 of Streets Atlanta). This is excellent. However, these are not principles, they are specifications. Generally speaking, clear specifications translate to increased uniformity and predictability, but it’s worth making a statement about what the principles are.

  • Forgiveness of the environment and of road users

Crashes are going to happen. However, when they do, the road environment should built in a manner that decreases the likelihood of injury. For example, GDOT is applying this principle when moving utility poles from the roadside so that when vehicles do run off the road, the consequences are not fatal (we'll see where exactly the poles are moved to see if people walking also were considered). Another example of this in Atlanta is the Luckie Street PATH Parkway. If you’re a cyclist, you’ll notice that the curb facing cyclists is at a slightly curved angle. This is because a cyclist hitting this curb is much less likely to fall off than a cyclist hitting the 90 degree curbs created for cars. Unfortunately, crashes will occur. We need to do everything possible to ensure that those crashes are not always a tragedy.

  • State awareness by the road user

This refers to a driver’s assessment of their fitness or ability to perform the driving task. Have you been drinking? Are you too tired? Are you not confident driving in the snow? These are the sorts of questions one must ask and answer before getting behind the wheel.



Why is it important to designate these principles? These principles operationalize the Atlanta's vision to designers and engineers, and are a means to transparently communicate to the public the goals of ADOT projects. As it stands, we can only evaluate projects in terms of whether it has elements that the community requests (e.g. sidewalks, lane widths, cycle lanes), and only if they meet the needs of a community after they’ve been built (e.g. how many crashes after the “improvements,” vehicle volume). It’s difficult to state whether or not a project will improve safety, but we can state whether or not a project follows established principles that we know are associated with increased safety.


The Atlanta Transportation Plan and its Technical memos are great reading for any transportation wonks out there. If you have some time, I highly recommend reading Chapters 3 and 4 of the Streets Atlanta design guide and the Safer Streets Technical Memorandum.

During Global Road Safety Week, I hope my fellow transportation professionals are taking a few minutes to think how we can save lives. No one in Atlanta should not be face a mortal risk when trying to get to school, work, groceries, or just go for a walk. With so many crashes on Atlanta’s streets, every single project is a safety project. As ADOT forms over the next few years, we need to think about what we want our streets to look like, and how to codify those priorities into policy.

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© 2018 by Dave Ederer.