Thinking Beyond the Bike Lane

There is a maxim that what you measure is what you get. A couple weeks ago, the Sacramento Area Bicycle Advocates (SABA) posted a map of Sacramento’s bikeway network to its Facebook page. The point, a good one, was to show that Sacramento’s bicycle network, like many city’s, has gaps and lacks connectivity. Furthermore, much of the existing bicycle network relies on sidewalks as designated bike routes and on bike routes and bike lanes running along streets with heavy high-speed traffic.

The City of Sacramento’s bikeway network, with bike paths, bike lanes, and bike routes and a lot of empty space.

How many top 10 lists for “Best Bicycling Cities” or “Healthiest Cities” include things like miles of bike paths? How many projects or city plans have talked about adding a number of miles of new bike lanes? However, much like Sacramento’s bikeway network, does it really matter if the bike lanes traverse multilane arterials with heavy high-speed traffic or if the bike path doesn’t take you where you need to go? How often does a bike lane suddenly disappear and put you out in the middle of high-speed traffic? Polls have consistently found that fear and safety concerns significantly deter people from bicycling. If the goal is a simple, connected bicycle transportation network that anyone of any age or ability would be comfortable using, just adding bike lanes or bike paths won’t get you there if few people are comfortable using them or if they don’t go anywhere people need to go.

A more useful way to look at Sacramento’s bicycle network would have been comfort or, more properly, “level of traffic stress” (“LTS” for short). Austin, TX, has been using comfort ratings since the early 1990’s, with high, moderate, and low classifications based on general characteristics of the street, such as traffic speed and volume, number of lanes, and presence of a bike lane. The comfort-level maps were not only more useful for showing people how to get from one place to another; they were also more useful for planning, because they better depicted gaps in the system.

Austin’s bike route “comfort” map, with high, moderate, and low-comfort routes in green, blue, red, respectively, as well as unrated routes, such as local streets, trails, and bike paths.

Then, in 2005, Portland developed a classification of four types. The “Level of Traffic Stress” system was both a planning tool and a marketing tool. By better understanding the level of traffic stress that discourages people in Portland from bicycling, the City could better understand their needs and address needs. Based generally on its experience working with the public, the City developed four classifications – “strong and fearless” (less than 1%), “enthused and confident” (about 7%), “interested but concerned” (about 60%), and “no way no how” (about 33%). Subsequent research has confirmed Portland’s approach through extensive surveys of Portland and the surrounding region (as a result, other metros may have slightly different distributions). The Federal Highway Administration and American Association of State Highway and Transportation Officials use a skill-based system with A, B, and C ratings, but planners have found Level of Traffic Stress more useful, because it not only considers what people can ride, but also what people will ride. Other methods, such as Bicycle Level of Service and the Bicycle Classification Index are also used, but require complex modeling and much more information.

How the general population breaks down. The “strong and fearless” will ride just about anywhere, but the “interested but concerned” will not tolerate traffic stress levels above 2.

The Mineta Transportation Institute at San Jose State University later developed a four-tier classification of traffic stress, “LTS” 1 through 4, with 1 the least stressful and4 the most stressful. The Mineta Transportation Institute developed  a detailed set of criteria for classifying street segments. In general, LTS1 would be a bike path, cycle track, or quiet street with light, low-speed traffic. On streets with parking, people have ample space outside the door zone. LTS1 is considered suitable for nearly all people, including children. At LTS2, prevailing speeds may reach 30mph and a street may or may not have a bike lane with on-street parking and may also have more than one lane in each direction. At LTS3, the street may have 2 or more lanes in each direction and prevailing speeds may reach 35mph. LTS4 is simply defined as more traffic stress than LTS3. In addition to street configurations, the Mineta model looks at intersections, distances between destinations, and detours necessary to avoid high stress streets (75% of utility bike trips are within 10% of the shortest route distance and 90% are within 25%). As a frame of references, “interested but concerned” people will generally tolerate LTS2. When the City of West Sacramento adopted its Bicycle and Pedestrian Master Plan in 2013, it planned its bicycle routes around LTS2. The Mineta Transportation Institute has found no evidence that bike routes (“sharrows”) diminish perceptible stress level in any significant way.

By mapping traffic stress, the Mineta Transportation Institute could more effectively where the City of San Jose needed to improve its bicycle transportation network most.

As an example, the City of Sacramento is evaluating potential “complete street” improvements to the Broadway St. corridor that would make the street friendlier to bikes, pedestrians, and transit. Broadway, between Riverside Blvd and Alhambra Blvd, has four lanes of traffic (two in each direction), mostly with no medians, street parking, no bicycle lanes, and a posted 25mph speed limit (whether the 85th percentile prevailing speed is actually 25mph is another matter entirely). Using the Mineta model, Broadway, even with a 25mph speed limit, has a traffic stress level of 3. Few people would feel comfortable riding on Broadway. However, converting Broadway from four lanes to two and adding a center turn lane, medians, and bike lanes, while retaining street parking and the 25mph speed limit, would reduce the level of traffic stress to 1. Broadway’s example shows how mixing bicycles with multiple lanes of traffic, even at low speeds, can nonetheless result  significant levels of traffic stress that would deter many from using a bicycle. This is a much simplified analysis, as a complete analysis would evaluate additional factors such as those mentioned above.

Another example, Folsom Blvd between 48th and 52nd Street, does have a bike lane and only one lane of traffic in each direction, but it also has a 35mph speed limit, resulting in a level of traffic stress of 3. However, since the south side of Folsom Blvd. has street parking, but no bike lane, and the Mineta model uses the “weakest link” to establish the stress level for a segment, the actual traffic stress level for Folsom Blvd. is actually 4! It is easy to why, when the City of Sacramento held a neighborhood meeting to discuss the possibility of replacing the bike lane on the north side of the street with parking, many attendees protested, because they thought that part of Folsom Blvd was dangerous enough already. Others stated that they did not and would not ride a bike on that part of Folsom Blvd, because there was too much traffic going too fast. The City could replace street parking on the south side of the street with a Class 2 bike lane, but that would only lower the the level of traffic stress to 3. Lowering the prevailing speed would help, but with the current 35mph speed limit, only a cycle track (also often referred to as a “separated bike lane” or, under recent revisions to the California Street & Highway Code, a Class 4 bikeway), off-street bikeway, or other separated facility would reduce the level of traffic stress below 3 and make the street tolerable for a majority of people on bikes.

Folsom Blvd. looking east.

Folsom Blvd. looking east. Even with a bike lane on the north side of the street and only one lane of traffic in each direction, the 35mph speed limit results in a level of traffic stress of 3. The south side of the street, which lacks a bike lane, has a level of traffic stress of 4.

Broadway and Folsom Blvd demonstrate that there is more to building a bicycle network than just adding bike lanes. Traffic speeds, street width, on-street parking, and other factors significantly influence a network’s usability. Mixing bikes with traffic, multi-lane streets, and traffic speeds, especially speeds in excess of 30mph, all have big impacts on traffic stress and on a 35mph street, only a cycle track or other separated facility results in a level of traffic stress that most people will tolerate. Hopefully, instead of maps just showing us bike lanes and bike routes, we can instead have maps showing us routes by traffic stress level, because these maps will tell us what we really want to know – how to get from point A to point B comfortably, safely, and conveniently.

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