What is Level of Service (LOS)? 

A “Level of Service” (LOS) rating system was used in the past as a means of determining projected traffic impacts of proposed developments on nearby intersections, streets, and highways. The LOS measurement system assigned alphabet letters to the various degrees of projected traffic congestion and intersection backups. For example, a roadway or intersection with only light traffic and few significant backups were assigned a grade of “A.” As congestion worsened, the letters progressed. For example, a grade of LOS “E” or “F” signaled severe and excessive traffic congestion. Understanding these effects early in a development’s design phase gave planners a tool for controlling the situation by requiring developers to adjust their designs and project plans to avoid congestion on nearby roadways.  

As defined under Senate Bill (SB) 743, LOS is no longer evaluated as part of CEQA, and Vehicle Miles Travel (VMT) is the new standard for assessing the effects of growth and development in California on the transportation system. 

What is Vehicle Miles Traveled (VMT)? 

“Vehicle Miles Traveled” (VMT) measures the distance a motorized vehicle will travel to a destination, divided by the number of passengers (i.e., per capita). Typically, developments located farther from retail, office, and other uses with poor access to transit result in more driving (and VMT) than developments situated close to complementary uses and transit. Cities use VMT to evaluate greenhouse gas (GHG) emissions and some transportation impacts. 

As excessive automobile use began to cause environmental damage in terms of fossil fuel consumption, GHG emissions, and severe traffic congestion, there was an increasing interest in placing limits on the amount of driving that could occur in an area. This concern led to the use of VMT as the preferred metric to evaluate a project’s impacts on the transportation system. VMT is used in transportation planning to measure the amount of travel for all vehicles in a geographic region over a given period, typically one year.  

Will the shift to VMT change the CEQA process?  

While the overarching CEQA process will not change, evaluating VMT (as opposed to LOS) will result in a paradigm shift as some projects not exempt from CEQA transportation analysis as evaluated with respect to LOS may be exempt from CEQA transportation analysis under VMT. The hope is this shift will more accurately assess a project’s impact on the environment, which will result in more environmentally friendly development.   


To find out more, read about CEQA compliance. 

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