Against L.O.S.

By Sarah Jones

For decades, the gold standard for evaluation of street design has been “Automobile Level of Service” or L.O.S. — a measurement of the ease of movement for cars and drivers. However, the longer that L.O.S. has been used as a barometer, the greater it has grown in scope, becoming the singular defining factor in the success or failure of a street design.

Today, the ascendancy of L.O.S. is beginning to waver, as more and more cities see how a focus on L.O.S. can attribute to traffic fatalities and stand squarely in the way of Vision Zero.

A Brief History of L.O.S.

L.O.S. was developed in the 1950s to evaluate the adequacy of highways at a time when the primary objective of transportation planning was to facilitate movement of people between cities and suburbs by private car. The system grades the automobile flow of a street with a qualitative measurement, a letter grade from A to F, from free traffic flow to congested.

Despite creation for essentially car-exclusive roadways, it did not take long for L.O.S. to inch off the highways and into the primary measurement for city streets. From Los Angeles’ Sunset Boulevard to New York’s Queens Boulevard, we see the reckless relics of L.O.S.-led street design: easy speeding, unimpeded traffic flow, and gapingly wide streets that are impossible to cross on foot. When traffic engineers plan for optimal L.O.S., the street picks up conditions that are most dangerous to people who aren’t in cars. Interestingly, in addition to defining traffic speed, L.O.S. is described as a definition of “driver comfort level,” which needless to say takes precedence over pedestrians’ level of comfort on any street defined by the L.O.S. measurement system.

L.O.S. is used almost universally in the United States and is an essential tool for highway engineering. But in many places it has become an all-purpose planning device too, used as a measurement that affects what
kinds of projects are approved and what route they must take to get there.

In California, for example, L.O.S. was baked into the evaluation of all street design projects’ impact on the environment, under the California Environmental Quality Act. This meant that all development and infrastructure projects or policies — literally any proposal subject to discretionary government approval — underwent a rigorous analysis of the potential for impacts to the environment. The idea of judging environmental impact is well-intentioned. If a project could result in release of hazardous materials, for example, the need for approvals is clear and unequivocal. But as our understanding of urban transportation advances, the need for a more subjective and value-derived system of judgment becomes clear.

Bike Lane L.O.S.

Until recently, under the California Environmental Quality Act, traffic congestion — as represented by a poor L.O.S. grade — meant that a project’s impact on the environment was considered “significant” and required the preparation of an Environmental Impact Report (costing hundreds of thousands of dollars and taking several years to complete), as well as special requirements for project approval.

Needless to say, pedestrian, bicycle and transit projects didn’t fare well in that system. Thinking about reducing the number of traffic lanes to give more room for sidewalks? Better have your environmental consultant on speed dial! Want to put in some bike lanes? Get ready to do an Environmental Impact Report — like we did in San Francisco, to the tune of $2.5 million and three years effort from court order to completion, just to produce a master plan for bicycle infrastructure. With L.O.S. omnipresent in traffic engineering regardless of road type, and places like California where L.O.S. triggers a mess of high-cost hand wringing, it is no surprise that the cities do not do everything possible to create safe streets.

In 2013, California passed a law that explicitly prohibited use of L.O.S. It was the first step in shifting the focus of transportation analysis away from measuring vehicle delay and toward methods that encourage reduced greenhouse gas emissions, multimodal networks, and mixed land uses. In other words, true environmental impact. California told cities that the time had come to reward and incentivize street networks that are safer and easier places for a person to move around outside of a car.

Tomorrow’s Gold Standard

California’s new law was a monumental milestone; adopting a replacement metric was the next step. Today, California’s transportation impact assessment identifies three areas of impact that cities must consider as they engineer streets. Powerfully, each has a direct connection to collision risk and a direct goal of putting fewer cars on the road. First, new transportation developments must be evaluated by the expected increase in Vehicle Miles Traveled (VMT) they would cause. Second, transportation projects must consider the possibility of “induced travel,” (like the addition of street capacity making car use more prevalent, or the decrease of street capacity easing the use of cars, or the addition of opportunities to use bicycles reducing the need for car ownership). The associated technical advisory suggests that cities also consider the potential for a project to result in danger, like increasing vehicle speeds or creating longer crossing distances for pedestrians.

California was looking for ways to streamline environmental review of projects in urban areas and better achieve greenhouse gas reduction goals. Safety and reduced collision risk were not the primary reasons for changing what was considered a transportation impact, but the change in law has positioned California cities to tackle Vision Zero in a way they never could when policy compelled them to prioritize car traffic over all else.

The new California Environmental Quality Act standards have met with resistance from suburban and rural communities and highway advocates in the state, and the approval process is still underway. However, cities have a legal right to adopt their own standards, and now have all the tools they need to set those standards around a framework of complete streets and places for people instead of cars. San Francisco was the first city to adopt the new guidelines, and Oakland followed suit, with other places considering the change instead of waiting for the State adoption process to be completed.

Level of Vision

San Francisco’s pedestrians and bicyclists are already benefiting from the new evaluation criteria. On 6th Street in the South of Market neighborhood, home to one of the highest rates of injury collisions in the city, the San Francisco Municipal Transportation Agency’s 6th Street Improvement Project is preparing to widen sidewalks, add corner bulb-outs, and reduce vehicle travel capacity, and as of press time, is proceeding through approvals without requiring a costly and time-consuming Environmental Impact Review.

Other projects reflect the relationship between Vision Zero and planning unyoked from L.O.S. even more explicitly: after a fatal crash in summer 2016, the Municipal Transportation Agency was able to fasttrack improvements to 7th and 8th Streets, including protected bikeways, safety zones, and transit boarding islands, making these corridors safer and more comfortable for all modes. This project — which once would have needed extensive review for L.O.S. impacts and ultimately may have been modified to maintain vehicle speeds — was approved by November of the same year and will be under construction less than a year after the tragedy that brought the dangerous conditions to light.

As long as vehicle L.O.S. is a defining factor or an exalted yardstick by which planners measure effectiveness, it will be that much more difficult for cities to reach Vision Zero.

Reaching Vision Zero will take concerted effort across all of the forces that influence travel in our cities. As long as vehicle L.O.S. is a defining factor or an exalted yardstick by which planners measure effectiveness, it will be that much more difficult for cities to reach Vision Zero. Just as we must create complete streets that protect people from traffic death and severe injury, we must step away from L.O.S. There is a long list of reasons to stop using L.O.S. as a way of shaping urban streets, but chief among them is that vehicle L.O.S. is in direct conflict with safety, and we will never reach Vision Zero without putting L.O.S. at the bottom of that list.

[This article first appeared in Transportation Alternatives’ Vision Zero Cities Journal in 2017.]

Sarah Jones is the Planning Director at the San Francisco Municipal Transportation Agency (SFMTA), where she leads a team of 40 transportation planners in a variety of multimodal short- and long-range planning efforts for San Francisco’s transportation system. Prior to joining SFMTA, Sarah spent 10 years at the San Francisco Planning Department, including three as Director of Environmental Planning. In that role, she initiated San Francisco’s elimination of vehicle L.O.S. as a measure of environmental impact. Sarah holds a Bachelor’s Degree in Urban Studies from Stanford University and a Master of City Planning from the University of California at Berkeley. She lives with her family in San Francisco.



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