Reconsidering Level-of-Service (LOS)

Santa Monica & Wilshire
Definitely not included in traffic counts!

The Atlantic Media Group’s Atlantic Cities site features a look at the evolving relationship between urban sustainable transportation policies and the standards and practices put in place by local governments to assess and forecast vehicular traffic demand. There is a movement underway in popular and academic circles to revisit the use of multi-modal level of service indicators (or ‘LOS’ in transportation parlance) as an appropriate metric for evaluating projects and polices under California’s Environmental Quality Act (CEQA). Journalist Eric Jaffe’s piece looks at San Francisco’s initiative to  rethink the value of LOS in the changing context of urban mobility, where moving people rather than vehicles needs to be the focus of transportation policymaking.

The Problem With LOS

Traffic counts in the business triangle
Traffic counts are the first step in calculating level-of-service.

LOS indicators provide transportation planners and engineers with a ready metric for vehicular flow. Without getting too much into the weeds, LOS is a benchmarking tool adopted by policymakers and transportation planners to gauge existing vehicular throughput and congestion.

Level-of-service table for business triangle
Translating traffic counts into project net traffic change appears like science but it is more of an art!

Under LOS guidelines, road conditions or intersections are evaluated for speed, flow and congestion-related delay; the corridor or intersection is then assigned a letter grade from A-F that represents abstractly (and simply!) vehicular traffic ‘demand’ relative to road capacity.

LOS is a commonly-used benchmark because it is clear and understandable and, well, because it is commonly used. That tautology masks the readily apparent conveniences of the LOS metric. Existing inputs like traffic counts fit well with the LOS formula because it measures vehicular flow exclusively (at least as currently employed). Transportation departments need not retool any processes because they all are already well-ingrained in professional practice. Consultants that prepare environmental reviews need not invent a new wheel and students come semi-prepared from planning programs to use LOS tables.

The LOS wheel rolls along largely because policymakers too need not learn new models for impact thresholds. According to a multi-part piece in SF Streetsblog, LOS is a pseudo-science that keeps rolling along.

One model of reform has emerged in the Bay Area. San Francisco has earned a well-earned avant garde reputation for doing things differently. A compact city/county of fewer than one million souls and a perpetually left-leaning board of supervisors, it’s been fleet-footed on all manner of social and environmental concerns. It’s no surprise that city planners have staked out a relatively radical position tying LOS to something beyond vehicular flow, namely community health and environmental quality.

Indeed, active-transportation advocates question the prudence of the LOS framework precisely because it appears to measure what we don’t necessarily need to measure: vehicular traffic alone. In the larger context of mobility, and particularly where community health and the environment are concerned, it’s looking more and more like facilitating vehicular traffic flow is not the solution but more of the same problem.

Only Engineers Seem to Like Level-of-Service Indicators

To a traffic engineer, LOS is a reasonable benchmark against which to measure policy or project impact. But the formulas set out in transportation manuals and communicated to every transportation planning student does not actually reflect real-world conditions in an area like Los Angeles, critics say. (In my experience, every traffic consultant engaged by project opponents come to a significantly different estimation of net traffic impacts than does the draft environmental impact report which contains the official estimates.)

For those not inclined to place faith in traffic engineers and policymakers, those traffic studies are a pro-forma exercise designed to facilitate development rather than accurately forecast impacts. The vehicle counts that are the basis for the studies are frequently disputed. Yet those figures and the formulas based on hypothetical impacts they’re plugged into have animated opponents inclined to question the credibility of the environmental review process.

Now, it’s important to measure vehicular traffic precisely because it’s so closely related to things we want to avoid: fuel inefficiency; greenhouse gas emissions on the increase; and that never-ending procession of injuries and deaths arising from motor vehicle collisions. Ted Rogers over at BikingInLA does a heroic job of tracking those calamities, and to date they total 65 confirmed traffic-related fatalities in year-to-date in Southern California and 21 in Los Angeles County alone.

But for opponents, an inherent limitation in LOS projections is compounded by measures (like turn pockets and signal timing) that often seem  insufficient to the task of mitigating a net anticipated increase vehicular traffic flow. Such concerns highlight an overall lack of confidence in LOS as a metric under CEQA.

Measuring flow as a benchmark for evaluating projects and policies seems like a dead-end metric to transportation advocates too for LOS is an abstraction that says little about mobility problems or opportunities. It merely indicates a relationship between vehicle throughput and roadway capacity. It doesn’t account for non-vehicular modes of travel including feet, bicycle, and rail.

Moreover, because LOS counts cars to the exclusion of every other means of transportation, it is silent on ped or bike mode choice, and silent on road safety.  It says nothing about what it’s like for people who choose to walk or bike to navigate among frustrated drivers in an overburdened intersection.

If counting vehicular traffic alone doesn’t take into account the complex issue of urban mobility, shouldn’t we be measuring what we want to measure? Think of road diets and you’ll understand why viewing such an improvement from the motorist’s perspective exclusively would be looking through the wrong end of the telescope.

What’s Wrong With This LOS Picture?

Wilshire & SM intersection aerial viewIf Beverly Hills is any indication, level-of-service is an abstraction with little application in the real world. We have several intersections that are so substandard relative to traffic volume that they are acknowledged by transportation officials as level E or F (among the worst LOS ratings). These intersections are also dangerous for people who walk or ride, however – a condition for which our Transportation Division employs no metric.

South Beverly & Olympic intersection overview

The Wilshire/Santa Monica (above) and Olympic/South Beverly (at right) intersections, for example, are acknowledged as safety concerns for all road users, yet improvements are slow to come to the aid of the walkers and cyclists who move through them. This was highlighted by a September collision at Olympic/South Beverly that resulted in a cyclist’s injury and property damage. It was an event avoidable merely by marking travel lanes to eliminate ambiguity and avoid unnecessary conflict.

That intersection remains unimproved; indeed it is not due for a safety upgrade for about a year. And that planned improvement is all about vehicular traffic flow.

Bike Backbone map missing Beverly Hills piece
Beverly Hills is the missing link in the emerging regional bikeways network.

Wilshire/Santa Monica too will wait – until mid- late-2013 under the SM Blvd. corridor improvement project. And this key east-west cycling corridor and bike backbone route may yet not even sport a dedicated bicycle lane, according to our most recent meeting with city officials.

With a standing policy of increasing vehicular throughput as a primary concern in Beverly Hills, it’s not surprising our city does not pursue pro-bike enhancements or facilities like bike lanes. Bus rapid transit corridors too don’t fit into the LOS picture and our city has declined to support them.

Policy objectives may favor environmentally-sustainable forms of transportation, and indeed it says as much in our Beverly Hills Environmental Sustainability Plan (2009) and other plan documents, but you won’t see such concerns reflected in the new BH traffic thresholds (adopted Fall of 2010). Thresholds trigger environmental review yet they are all about vehicular flow: like the old, they refer only to car trips generated. (We can’t link to the Sustainability Plan because it’s not even posted on the city’s website.)

What if a policy were formulated to help shift some of the projected increase in auto trips to other modes of travel? Wouldn’t that make new projects less taxing on our roads? We won’t know because we don’t count such non-vehicular trips. So, Beverly Hills Transportation Division officials can tell you all about LOS intersection-by-intersection, but they can’t tell you how many folks ride, or anything about safety because they simply don’t keep collision figures. (Bike blogger Ted Rogers probably knows much better about that than do our own officials.)