If we are going to change the way our streets and communities are designed, we will need to change the way we measure their performance. Read more about that (and some other important changes) in this recent story:įeds get out of the way of communities that want to design safer, more complete streets The 1965 federal Transportation Research Board Highway Capacity Manual introduced the LOS metric and it quickly became accepted as the standard measure of roadway performance. One reason that states adopted the LOS so quickly was that it suited our country’s transportation goals in the 1960’s of building out a network of interstates and prioritizing automobiles to travel quickly.Īlthough LOS quickly became the standard, transportation agencies at any level are not explicitly required to use it: there are no planning or project design requirements that mandate the use of either LOS or travel modeling. FHWA recently issued a memo clarifying that level-of-service was never a federal requirement. This terrific cartoon from Andy Singer that Toth includes shows the rationale in practice: As Gary Toth from the Project for Public Spaces brilliantly put it in this piece, transportation professionals, “in search of high LOS rankings, have widened streets, added lanes, removed on-street parking, limited crosswalks, and deployed other inappropriate strategies” all because LOS has been the de facto standard over the last 50 years. This heavy reliance on LOS has dramatically shaped our cities. ![]() ![]() If a road is projected by traffic engineers to lack capacity 20 years in the future - an incredibly fuzzy practice that’s far more art (or magic?) than math - that road still receives a failing LOS grade today, even if the road is adequately suiting capacity needs. Next, traffic engineers project the amount of traffic on the road in 20 or 30 years to determine if the road has enough capacity to cover the lifespan of the asset. The LOS measurement is calculated by first measuring the amount of traffic during the busiest 15 minutes of an evening rush hour. Traditionally, roadway conditions are acceptable if they score a C or higher on non-urban streets and a D or higher on urban streets. A, B and C represent free-flowing conditions and F is stop-and-go traffic. The score is assessed based on the highest level of congestion on that roadway, even if it only occurs a few minutes a day. Letters designate each level, from A to F. Level of service is a system by which road engineers measure how well a road is performing based on the number of cars and the delay that vehicles experience on that roadway. ” Because of the ubiquity of LOS, this largely misunderstood measurement has profound influence on the design of our communities. According to Jason Henderson, professor of geography at San Francisco State University, “Every city I’ve ever come across has some use of. Though there are no formal or federal requirements to do so, most DOTs, metropolitan planning organizations and traffic engineers rely on a metric known as level of service (LOS). Heard this story before? What is level of service, and how do DOTs come to this conclusion? Worse yet, the community is told that in order to make a street safer, they actually need to widen it and smooth out any curves, making it a virtual speedway, undercutting their plans to build a place with more enjoyable places to walk and visit - a framework for creating economic prosperity. But as the street is also a state highway, they soon hear from the state department of transportation (DOT) that their proposed changes will slow down traffic and fail to meet “level of service” requirements and won’t make the cut of the state’s short list of projects. ![]() Wanting to rejuvenate their local economy, a community cooks up plans to redesign the local street running through downtown that was perhaps even short-sightedly widened or converted to one way travel in the 1960’s or 70’s. So what is this outdated “level of service” measure and how can other states follow California’s lead? | Posted by Steve Davis | 3 Comments | california, Capital Ideas, level of service, state funding & policy, trafficĬalifornia made a small but crucial change to how they measure the performance of their streets in 2013, shifting away from a narrow focus on moving as many cars as fast as possible and taking a more holistic view and measuring a street’s performance against a broader list of other important goals.
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