"There's a dirty little secret you should know about San Francisco: It's engineered first and foremost for automobility and will never be able to shed this bias if the traffic engineers are in the driver's seat wielding their traffic analysis tools like bibles. As long as the city continues prioritizing the use of transportation analysis known as Level of Service (LOS), you might as well burn our Transit First policy for warmth.
"On the one hand, LOS is a very simple and blunt metric for understanding the speed that vehicles can move about the city. LOS measures the amount of vehicular delay at an intersection, with A through F grades assigned to increased delay. This measurement is taken during the peak 15 minutes of evening rush hour and if an intersection slips from LOS D to LOS E, traffic managers will try to mitigate the impact, which usually means widening the road, shrinking the sidewalks, removing crosswalks, softening turning angles, and adjusting signal timing to speed the movement of vehicles.
"The result of relying on this poor methodology to shape the growth of cities has a profound affect on the politics of human mobility, privileging the movement of vehicles before the movement of anything else. Quite simply, LOS analysis has given us Phoenix and Atlanta, congestion and ever-longer commutes, and a whole host of ills that accompany reliance on the inefficient use of street space for our cars."
Thanks to George Osner, AICP