Many communities work with developers to assess the impact on the community of a proposed development project and identify appropriate actions to reduce or mitigate any negative impacts. Until recently, most communities measured the transportation impacts of new development in terms of the automobile traffic expected to be generated and did not consider multimodal options for getting around.
As a result, development projects were assessed based on automobile level of service (LOS), which measures vehicular, but not person, mobility. LOS analysis uses an A to F scale, where LOS A means that the number of vehicles on the road is well below the road capacity and LOS E—F indicates that the roadway is at or over capacity. The driving experience is unimpeded under LOS A, while under LOS E—F, drivers are in “stop-and-go” conditions. Ironically, places with the most F-grade intersections tend to be our most vibrant neighborhood commercial strips and urban centers.
When a development is predicted to impact level of service, cities often require developers to “mitigate” that impact by improving automobile traffic flow, for example, by widening a roadway or adding turn lanes. These solutions force roads to be built at excess capacity and engineered for nonstop, high-speed automobile movement, all of which have a negative impact on people walking, bicycling, or riding transit, and can induce the very traffic that they are designed to relieve.
LOS-optimizing solutions can cause a variety of unintended outcomes, including depressed development, degraded walking environments, and undermined placemaking efforts.
The methods used to analyze level of service also tend to focus on traffic conditions during the most congested periods of the day, forcing roads to be built to handle the expected automobile demand that might only occur for 15 or 30 minutes during rush hour. Solutions that “fix” traffic at peak times are all the more inappropriate at off-peak times of day, leaving less space in the roadway for street trees, bicycle facilities, or sidewalks.
Cities are increasingly deciding that LOS measures are just one element in the range of mobility options available in more urban, walkable, and transit-rich neighborhoods. Many cities today aim to attain LOS C—D, but if you’re building a great neighborhood with many transportation options, stop-and-go traffic during the morning and afternoon rush may be a trade-off that businesses, workers, and residents are willing to accept. You should have that conversation through community planning processes instead of forcing developers to widen roads in an effort to avoid impacting level of service.