Monday, July 18, 2011

The Tyranny of Levels of Service

The Sustainable Cities Initiative just posted the final report for the Downtown Circulation Study (43pp, 3MB).

On first glance, it is, alas, a significant disappointment. While the cover shows lots of groovy bike-friendly imagery, inside it's all about levels of service and adverse impacts on motor vehicle traffic volumes.

Its solutions are, in a word, unsustainable.

It is likely the studies' limits arise from auto-centric constraints imposed by City staff. Two in particular, leaving car parking untouched and maintaining motor vehicle "levels of service," have almost certainly hamstrung the project. Even if the students wanted to go elsewhere with solutions, the framing and scope limited them. So while it may seem ungracious to critique the students' work, the main criticism here is of the assumptions they inherited rather than their work product.

Still, the auto-centrism in a ostensibly bike-friendly analysis underscores a key structural limitation, a parochialism, to the way we think of mobility.

Bike Lanes on High and Church

As for the report contents, some projects receive multiple discussions, but there are essentially eight project analysis sites:
  • Addition of Bike Lanes to High and Church Streets
  • High Street / Church Street Two-way Conversion
  • Union Street and Commercial Street Crossing
  • Commercial Street Bike Lanes,
  • Evaluation of the Y Intersection at Commercial Street and Liberty Road
  • Bike and Pedestrian Crossing at Wallace Road
  • Wallace Road Multi-use Path
  • Edgewater Multi-use Path Realignment
To see how Levels of Service gets in the way of real mobility choice, let's look at one of the projects. Here's the conclusion from the "Addition of Bike Lanes to High and Church Streets."
The adverse effects of lane removal are clear (see Figures 3 and 4); the Level of Service for motor vehicles is reduced at the intersections with Marion, State, and Court Streets with the addition of a bike lane.

The placement of the dedicated bike lane on either side of High and Church Streets may not be a practical solution if the current Levels of Service must be maintained.
But are things really so bad?

Out of 14 intersections, only four are modeled to show a change in service level; each of those four changes is only one level, in three cases from "free flow" to "reasonably free flow," and in one case from "reasonably free flow" to "stable flow."

To say "the adverse effects of lane removal are clear" is to exaggerate somewhat. Moreover, the gain in bike service hardly makes a total "loss" of service! But this is an example of the way Levels of Service analysis can limit and muddle rather than clarify.

Levels of Service

Whether the street is a neighborhood cul-de-sac where children play most of the day and cars are parked and rarely in motion, or a 5 lane arterial without parking, the primary customer and user of the road system is always defined as a car. One problem with Levels of Service analysis is that it counts motors, not people. Another is that it makes no qualitative distinctions between streets.

Together, the counting error and the qualitative error make for modeling divorced from reality.

Here's the math:
empty bus = 1
full bus = 1
carpool with 4 passengers = 1
car on drive-alone trip = 1
person on foot = 0
person on bike = 0
In each of these the relevant atomic unit is the motor vehicle. Whether the motor vehicle actually has people in it is irrelevant.

Additionally, there is no qualitative distinction in "levels of service" between the bucolic neighborhood street and the near-highway. The only thing that matters is the volume/capacity ratio for cars. The model treats a street like a firehose: How many cars can it shoot out?

In this way the road system as currently defined exists to serve cars only. Place, context, and number of people traveling are all abstracted out of the model. "Enhancements" for people who walk and bike or use transit are add-ons. This accounting represents a triumph of mechanistic abstraction over human reality.

And though a bike lane represents a different way to deliver people to and through an area, Levels of Service analysis counts it instead only as a loss, a subtraction of capacity.

In the downtown study, for nearly every project analysis improving bike connectivity and multiplying the ways a person might choose to go somewhere "negatively" impacts Levels of Service defined as motor vehicle capacity alone. What should be a way to increase mobility choice is instead viewed as a loss of service.

This is nuts. But is has consequences for the bike plan update.

Bike and Walk Salem

The City's dependence on mono-dimensional Levels of Service also appears to be limiting the Bike Plan Update process. The recommendations appear to represent a limited and very incremental evolution in applying a veneer of biking and walking connectivity - and the draft ideas do not extend where this connectivity might negatively impact the motor vehicle capacity.

Because the contractual scope includes revisions to the Biking and Walking chapters only, and leaves the core Levels of Service framework untouched, the update risks being more cosmetic than substantive.

The update process is still a good thing - but it could be so much more, and it is likely that we will all have to revisit things in another five or ten years. At some point we will begin to think seriously about serving people, about the movement of people who might wish to travel any number of different ways, and who want to feel they have a genuine suite of choices.


Walker said...

Dude, you are on fire. This is your best yet. Good job.

Now stroll over to the development code rewrite project and sit a spell ... You will notice after a while one thing: we place insane regulations on what you can do INSIDE the buildings because we assume, from the start, that we're not allowed to do anything to limit the negative impacts caused by cars. Thus, to keep idiots from making life awful for neighbors with cars and trucks, we play a game of trying to guesstimate how many trips various uses will create and when, and then we write a code that, at it's heart, is all about trying to limit negative effects of cars, _without ever addressing cars._

It's the municipal version of golf, where the whole thing (put a ball into a series of holes) would be boring and easy unless you made it hard with an absurd approach, like making the players use a ridiculous club that is poorly suited to the task.

Thus, instead of trying to directly place limits on service vehicles, we allow bureaucrats to investigate and make decisions about what a business owner can do with a property. So we have a bizarre development code that ignores the market and actually discourages what we claim to want (people living and working downtown) with codes that make it impossible, all because we'd rather force businesses to jump through land use approval hoops based on old ideas about how each use works, rather than tell business that they can do what they like as long as they are a good neighbor and dont inflict negative effects on their neighbors. The great example is the brew pub, which gets a different answer from the land use approval office if it's predominantly a restaurant or predominantly a brewery, a kind of factory. There's no room for an entrepreneur to say, " gee, I dunno, but how about I start out and we'll see what the public likes best and which sells the most.". Nope, we force the business to declare so that we can assess how many trips each place will generate, because, at bottom, that seems to be what the discussion on land use is all about: recognizing without ever saying or admitting that cars are the problem.

Right now, the kind of urban vitality that would bring jobs and people into downtown is against the development code.

Jeff McNamee said...

This is a great entry, Eric! Salem is so stuck in its auto-centric ways I am sorta at the point of complete confusion. Maybe that's why I focus on dirt instead of pavement. There are many businesses that suport more sustainable modes of travel downtown...I just hope they speak up!! We need a bike advocate, that is not afraid to argue for multiple modes of travel, on the Commission. The one we have seems to intimidated by autos.

Gary said...

Jeff - what commission are you referring to?

Eric, others,
yes, Level of Service has been way over-utilized in the last few decades, IMHO. Between the calculations used in the methods, and the very models used to predict future volumes, we've developed a dumbed-down planning process to think for us. The current planning process, as this and most other studies follow, does not take into account a city's ability to flex and morph as needs arise, as some streets get a bit more congested when a change is made, as other areas become ripe for development to meet a demand. I listened to a great presentation by Ian Lockwood ( where he went through some great case studies in road diets, street densification, and solutions for suburbia. The link is a sample of his style of transportation planning. He's a recovering traffic engineer who sees the shortcomings of models, LOS, etc. The points I take away from his presentation, which apply indirectly to downtown circulation issues are: 1) traditional models don't give cities (and people in them) any credit for changing behavior over time, i.e. development patterns and peoples choices of where they live/work/shop can change significantly in as little as ten years, and 2) changes to the network should not be made too abruptly so as to give people/city time to adapt. I'd bet that this new approach to transportation planning could solve the perceived need for a third bridge and many of the other transportation challenges of the downtown area.

Salem Breakfast on Bikes said...

@Walker - I'm sorry: I'm still struggling to absorb your comment. The brewery example is terrific and kindof a gestalt shift for me. I wish you'd write more about this on your home blog! We could use a detailed critique of the development code rewrite.

@Gary - The lockwood thing is 150pp+ of slides! Is there an executive summary? What I saw looked like a rehash of Jane Jacobs - mostly new urbanist stuff.

Anonymous said...

The Atlantic has an article on LOS, "The Transportation Planning Rule Every City Should Reform."

(Interestingly it was originally titled with the word repeal instead of reform.)

Anonymous said...

And here's a piece on the Projects for Public Spaces Placemaking blog.

Anonymous said...

BikePortland has a piece on an RFP for a developing a new multi-modal LOS analysis. It will be interesting to follow!