Activist groups waging war on urban auto use under the guise of pedestrian and bicyclist advocacy have found a new hook for their campaign: the “level of service” measure used by traffic planners to describe how efficiently a road works.
Traffic engineers use manuals to compare the hourly volume on a road or through an intersection with its theoretical capacity to determine how many lanes are needed. The resulting measure is called “level of service” or LOS.
“Level of service” is sometimes described by the six letter grades “A” through “F.” This is a shorthand way of describing how much freedom of movement a car driver has on the road or through an intersection. Level “A” is completely unimpeded as to speed choice and lane-changing. At Level “C” a driver faces only slight restriction on movements. “D” is at the threshold of congestion, where only the slightest disruption will bring flow to a stop. “E” is stop-and-go movement, and “F” is totally clogged with long stops.
Level “C” is the planners’ target, for economic reasons. An urban road that operates at Level “A” all the time is ideal for motorists but probably overbuilt; “C” is felt to represent the best value for the money. One other variable that must be understood is how many hours a year the road operates below “C.” Often, 30 hours a year was the standard for “recreational” routes carrying vacation traffic. That is, one hour of congestion on 15 Friday and Sunday evenings in each direction. For commuter routes, the standard is 200 hours or, say, half an hour each morning and evening on 200 of 250 work days a year.
It is judged wasteful to build capacity to reduce congestion below these limits.
Now anti-car activists are waging war on LOS, as they do with the 85th-percentile speed. You will hear booing at public meetings from doctrinaire anti-car activists if you mention either phrase. They maintain that achieving Level “C” on city streets is unrealistic, and cities should settle for Level “F,” with evil cars ceding the right of way to all other users of the road.
LOS is a valid measure for the value of improvements to congested routes, or filling gaps in the road network. Time lost to delay is still crucially important to people. And levels of service can be calculated for autos, transit, pedestrians and bicycles.
When anti-car activists urge local officials to abandon highway level of service as a measure, be prepared to demand that motorists get appropriate value for their road-user fees.