Understanding the 2035 Comprehensive Plan – Transportation

Last Tuesday the Council’s Sustainability and Transportation Committee heard a presentation on the 2035 Comprehensive Plan’s Transportation section, in one of a series of presentations to various Council committees on the different sections that make up the Plan.

As a reminder, the review schedule for the Comprehensive Plan looks like this:


Also: tonight at 6:00pm, there will be a public hearing in Council Chamber on the Comprehensive Plan, so if you have thoughts, that will be one of your opportunities to voice them.

In the presentation, the three main goals of the transportation section (or “element”) were laid out:

  1. moving people in a variety of different ways;
  2. moving goods;
  3. using the right of way to do a lot of different things.

Rather than walk in detail through the entire section, the presentation focused on four big issues that the city staff wrestled with in updating the plan:

  • Right of way (ROW) allocation;
  • Defining a “level of service” metric;
  • Safety; and
  • Integrating the individual “modal” plans.

“Right of way” allocation essentially boils down to how to prioritize the various uses of street space, when to prioritize certain modes of transportation over others, and integrating those modes together into an interconnected transportation system.

They proposed that streets have three “zones” of right of way: pedestrian space, vehicle travelway (including bike lanes), and a “flex zone” that could be used for a variety of things — and that most of the discussion and debate revolves around how to allocate flex space.

right of way zones

They think about this as a conversation about the six essential functions of right-of-way:

  • Mobility: moving people and goods
  • Access for people: people arrive at a destination or transfer between modes;
  • Access for commerce: goods and services arrive at their customers and markets;
  • Activation: parklets, food trucks, public art, and other public social spaces;
  • Greening: trees, planter boxes, rain gardens, and other environmentally-friendly features;
  • Storage: admittedly an “inelegant” and misleading name, this is for static, stationary uses such as long-term parking, bus layovers, reserved spaces for first responders, and construction areas. Storage is not just parking, though many misinterpret it as such.

There is a complicated mapping between the three kinds of right-of-way and their potential functions, with flex space being used for most of them. That complicates the conversation about how to allocate flex space, as we try to balance competing needs.

row uses

The key to making good decisions about how to allocate that right-of-way space is to answer the fundamental question: what are the different functions that a particular right-of-way needs to do? And you don’t answer that question on a city-side basis; you answer it by focusing in on the neighborhood, the zoning classification, all the way down to the block and lot.  Right of way in a single-family residential neighborhood needs to do very different things than in a neighborhood commercial area, an industrial area, or a downtown commercial area. Even within commercial areas, shopping centers need very different right-of-way than office buildings or entertainment districts. All that comes into play. The city staff also pointed out that right-of-way can be used different ways at different times of day, such as arterials that move a lot of cars during peak weekday commute hours but have plenty of capacity for parking the rest of the day. They are committed to using all of these factors in determining how to allocate right-of-way, and especially flex-time on the city’s roads.

The second big issue, level of service (LOS), is equally tricky but they are proposing a fairly significant change to align with updated priorities in the Comprehensive Plan. Since 1994, the Plan has used a metric for LOS called the “volume to capacity ratio” — what is the volume of traffic along a street compared to its theoretical maximum capacity.  The problem with this model is that it is very vehicle-on-roads centric, when in fact the goal of the transportation plan should be to enable the six functions outlined earlier (none of which are “move cars.” In the end, we care about moving people and moving goods, not really about the cars, trucks and buses that move them. The old metric also doesn’t look at our multi-modal transportation system holistically.

The new metric being proposed is “single-occupancy vehicles as a percentage of all the person-trips that people take in the city,” or “mode share.” It allows for analysis of how moving people from one mode of transportation to another can change the efficiency of our roads, like this:

LOS policy change

This is important because at this point, Seattle is built out, and there is no room to add more roads (except underground at enormous expense); the main way we will move more people and goods is by finding more efficient ways to use the roads we already have.

The old LOS overlays a map of Seattle with “screenlines” in various places and count (or forecast) traffic the crosses them as a way to identify the most important traffic flows in the city.


But in the new LOS system the city is divided up into zones, with goals for the maximum percentage of traffic that is single-occupancy vehicles during peak afternoon hours (3pm to 6pm) — since that is the time when Seattle overall is most congested.

los new zones

The good news is that while population is growing, daily traffic is on a long-term trend down and transit ridership is on a long-term trend up.

LOS trends

In the context of this focusing squarely on reducing (or keeping constant) the number of single-occupancy vehicles is a good thing. It’s probably over-simplifying to focus on only one metric, though.

The third big issue is safety; the last version of the Comprehensive Plan said little about it, but with Seattle’s new “Vision Zero” initiative to end traffic deaths and serious injuries by 2030, it needed to be incorporated and the two plans aligned.

The fourth issue involves aligning and coordinating the separate plans for different modes: freight, bicycles, walking, buses, street cars, light rail, and cars — with particular focus on the ones that need to share streets.

Council member Mike O’Brien, chair of the Sustainability and Transportation Committee, raised a couple of considerations in giving his feedback. First, he asked how the city thinks about transit investments when we ask developers to pay for traffic mitigation for their construction projects such as a new office building or condo high-rise. The city has indeed been thinking about that and would like to have a menu of options to present to developers that will influence the mode-share LOS metric, such as reducing the amount of parking they provide, giving out bus passes to its residents or employees, or even providing bike lockers and showers. They are open to the idea of investing in capital projects as well.

O’Brien also critiqued the way the current draft of the Comprehensive Plan addresses community engagement. The old Plan talked about it in every section; the new plan consolidates it into one “Community Engagement” section that is intended to apply to the entire document, but unfortunately gives many the impression that community engagement has been de-prioritized. O’Brien suggested that more explicit references to the community engagement plan should be added to every section so people know where to look to find it — and don’t simply think it was taken out.

Council member Rob Johnson, whose Planning, Land Use and Utilities Committee is spearheading the review of the Comprehensive Plan, raised some other topics that need further discussion:

  • how mode-share LOS targets get set for each neighborhood;
  • how the city does a better job of ensuring that transportation goals are aligned with environmental and growth goals;
  • how to highlight the “state of good repair” and health goals: in his view, transportation policy is “connective tissue” to several other goals such as these.

O’Brien closed out the discussion by noting that there is still more work to on the transportation section do before it’s ready to be approved, but it’s a thoughtful start at wrestling with some difficult issues.