I approve of this?

UPDATE: This post gives background information on the intersection. I have now ridden through it, and my opinion of it has changed. I have another post about it, and a video. Please check them out.

The image below shows a special installation of traffic signals and markings at the intersection of 16th street, U Street and New Hampshire Avenue NW in Washington, DC. To enlarge the image so you can read the text descriptions, click on it. You also may have a look at a Google map satellite view. Then please return to this page for my comments.

16th Street, U Street and New Hampshire Avenue NW, Washington, DC

16th Street, U Street and New Hampshire Avenue NW, Washington, DC

Pierre L’Enfant and Andrew Ellicott — and let’s also not forget African-American surveyor Benjamin Banneker — laid out Washington’s streets from scratch —  in the pre-automotive 1790s. Washington’s diagonal avenues give it an openness and unique sense of place — but the resulting uneven-length blocks and multi-way intersections make for some serious headaches now. Some traffic movements are odd, traffic signals can not be synchronized efficiently…

Before the new installation, no signals in this intersection faced new Hampshire Avenue. Bicyclists would sometimes use New Hampshire Avenue for through travel, though its conflicting one-way segments made that illegal and there was no conflict-free crossing interval.

The illustration above is from a page posted by the government of the District of Columbia describing a new installation of contraflow bicycle lanes, bicycle waiting boxes and special traffic signals. At first glance, these may raise the hair on the back of the necks of people who are suspicious of special bicycle facilities treatments.

Look again. The bike boxes look odd only because they connect with diagonal New Hampshire Avenue. They are cross-street bike boxes — which bicyclists enter from the left. Bicyclists from New Hampshire Avenue enter on a separate signal phase from the motor traffic on 16th Street, rather than to creep up on the right side of motor vehicles, as with more-usual bike-box installations. Motorists do not have to crane their necks or stare into a right-side mirror looking for these bicyclists.

The cross-street bike boxes are even more conflict-free than usual. Because only bicycle traffic runs contraflow, bicyclists do not have to negotiate with any right-turning traffic when entering the intersection.

To summarize: this installation, importantly, does not violate the fundamental traffic-engineering principle of destination positioning at intersections, as so many special bicycle facilities installations do.

Or, looking at the same conclusion from a different point of view, the installation does not require or encourage bicyclists to do anything dangerous or stupid, and it offers reasonable travel efficiency considering the situation it addresses.

I am not going to say that this installation is perfect. I can see the following issues.

  • Bicyclists’ having to wait through two traffic-signal phases is inconvenient and might lead to scofflaw behavior. A “scramble phase” could allow crossing in one step and might even apply to bicyclists arriving from other directions. It would reduce the time allocated to for all the other phases, but it might be practical, and preferable, at times of low traffic. Signals and markings which only apply at some times could, however, be confusing.
  • The installation addresses only bicycle traffic entering the intersection from New Hampshire Avenue. Traffic control remains as it was for 16th street and U street. Considering the many ways in which bicycle travel could be made slower and/or more hazardous in the name of making it better, this may be a case of “best leave well enough alone,”  but on the other hand, real improvements might be possible.
  • The bike boxes on 16th street could be interpreted as encouraging bicyclists on that street to overtake motorists on the right, then swerve in front of them, as is the more conventional with bike boxes.
  • Just outside the lower left of the picture on New Hampshire Avenue, there is wrong-way parallel parking next to the bike lane. Motorists exiting wrong-way parking spaces are in head-on conflict with bicyclists, but cannot see them if another vehicle is parked ahead. (See illustrated description of wrong-way parallel parking elsewhere, if the explanation here is unclear.) At the top right, on the other hand, note that the bike lane is farther from the curb: this segment of New Hampshire Avenue has back-in right-angle parking, avoiding the sight-line problem.
  • And, while we’re at it, I have another issue with the street grid, though it’s common to many other cities and not readily subject to correction. Streets that go east and west guarantee that twice per year,  for several days, the Sun will rise and set directly along the streets, glaring into drivers’ eyes.  If the street grid ran northeast to southwest and northwest to southeast, this would never happen. All you Pierre L’Enfants of today designing new cities, please take notice, here’s your chance to acquire a reputation as Pierre L’Enfant Terrible!

This installation is the subject of experimentation sanctioned by the U.S. Federal Highway Administration, with observation, data recording and analysis to see how it works in practice. The experimentation may turn up more issues, or reveal that some are of little importance.

Now, dear readers, you also may also have points to add to the discussion. Let the comments fly.

See also: GreaterGreaterWashington blog entry about this installation; Washington, DC Department of Transportation page about it; Google maps satellite view.

10 responses to “I approve of this?

  1. Considering that the intersection was kind of crazy to begin with, it does seem like a pretty elegant solution, except for the bike lanes proximity to parked cars on the southern leg of New Hampshire Ave.

    By the way, what is a scramble phase?

  2. @Eli Damon
    A scramble phase is most simply defined as one in which it is legal to cross the intersection in every direction. It is most commonly implemented for pedestrians, in which case it is also called a “Barnes dance”, after Henry Barnes, the brilliant traffic engineer, also a pioneer with traffic-signal synchronization, actuated signals and bus lanes.

  3. Scramble phase = demolition derby
    Anyone can go anywhere during a scramble phase. Don’t expect pedestrians to wait on the sidewalk while the cyclists play “cycle joust” and knock each over. Pedestrians will see ‘no cars,’ and walk into the intersection so they can join in the fun and be human bowling pins.
    So, seriously, John, why would a scramble phase be appropriate here? And if this intersection has unique qualities that make a scramble phase less dangerous, wouldn’t putting one here make the public clamor for scramble phases where the were more dangerous?

  4. If you have a pedestrian-only scramble phase, which is fine with me, bicyclists can DISMOUNT and walk their bikes through the intersection during the scramble phase. Then they mix with pedestrians reasonably well. But when they’re riding amid pedestrians, the safety record is dismal.

  5. @John Schubert, Limeport.org
    I was thinking of a bicycle-only scramble phase, and perhaps not for all entrances to the intersection but rather only to cross directly on Hampshire. This could be concurrent with pedestrian flow in the crosswalks across U street, as well. Whether a scramble phase is appropriate also depends on the traffic volume at a particular time. It is not going to be practical if the traffic volume is high. If the motor traffic volume is low, (late night, early morning, etc.) then the bicycle and pedestrian traffic volumes also are likely to be. You make a good point about pedestrian behavior, but bicyclists on Hampshire will most likely ride straight across the intersection, far from the curbs, where they will not be surprised by pedestrians.

  6. Thank you, John, for this article.

    I’ve commented before that it is possible to build these avant-garde bicycling facilities and actually get them right rather than wrong, i.e., to not violate good traffic engineering principles. However, it means doing one’s homework and being willing to pay to put in the proper infrastructure, i.e., extra traffic lights, and to impose additional signal phasing for more modes.

    Nothing wrong with any of that, but it does cost more than simply integrating cyclists into traffic. But if bicycling traffic increases dramatically, one might wonder if it is more efficient to phase traffic separately than to mix it together. Has anyone crunched the numbers?

    I sent your discussion to our traffic engineer and county DPW director, as we are about to start a study of modernizing one of our main roadways. The usual and uncritical “bicyclists mean bikelanes” arguments are surfacing. Sigh…

  7. “lex parsimoniae” in other words “best leave well enough alone”?

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