Yesterday, the city sent out a press release showing that the Stone Way “road diet” has improved safety on the street. The so-called diet converted the north Seattle street from a four lane road into one that has two lanes, a center turn lane, and bicycle lanes. Publicola summarizes the press release:

• The percentage of drivers exceeding the 30 mph speed limit on Stone Way by 10 mph or more dropped about 75 percent—from about 4 percent to about 1 percent. A pedestrian struck at 20 mph, according to studies cited in SDOT’s report, has an 85 percent chance of survival, compared to only 15 percent for a pedestrian struck at [a higher speed].

• While car traffic on Stone Way decreased 6 percent after the road was rechannelized, bike traffic increased a whopping 35 percent, with bike traffic representing around 15 percent of rush-hour trips on the road.

Traffic on neighborhood streets did not increase, as some neighborhood residents feared; instead, it actually declined substantially, with traffic volumes as much as 49 percent lower on streets parallel to Stone Way. Only two parallel street segments showed any increase—one, Woodland Park Ave. N. at N. 42nd St., climbing by 2 percent (three cars) at morning rush hour, and the other, Woodland Park Ave. N. at N. 50th St., increasing by 27 percent (12 cars) at morning rush hour.

• Collisions between cars and cars, bikes, and pedestrians declined dramatically—14 percent—after the new bike lane and sharrow were introduced. And collisions causing injuries fell even further—33 percent. Finally, car collisions with pedestrians declined even more dramatically —fully 80 percent.

Notably, while local businesses predicted endless traffic on the corridor, the city says that “volumes show the roadway still easily accommodates motor vehicle traffic.”

31 Replies to “Stone Way Road Diet Improved Safety, says City”

  1. I’m guessing this is a typo: “compared to only 15 percent for a pedestrian struck at 15 percent.”

  2. This is fantastic. I am glad this worked out well and hope it can be used on more city streets beginning yesterday.

      1. Well, the Viaduct will be going on a diet…right? 4 lanes in some cases to just 2!!

      2. Yeah knock it all down and replace it with a surface boulevard with two lanes each direction plus bike lanes, parking, and streetcar lanes down the middle.

      3. Or have a deep bore tunnel and have bike lanes and streetcar over the top of it…

  3. I’m glad this is getting press from you guys and Publicola but it is actually kind of sad that this is news. Many previous studies throughout the country as well as proven examples of road diet effectiveness should have solidified their efficacy long ago. Debating every proposed road diet is such a waste of time and resources.

    Without any significant funding for the PMP and the BMP road diets should be happening left and right, as the cheapest way to improve pedestrian and cyclists safety.

    1. Road diets have not been done much in this region, so even if there is evidence elsewhere, people here are not familiar with it.

  4. I hope the folks along Nickerson St. see this. It’s close by. Lessons to be learned, again and again.

    1. I second that motion.

      23rd is like a freeway. When I walk to/from work, I cross 23rd at Pine (it’s a long way to the signaled intersections) and I feel like Frogger.

      And I don’t recall ever seeing a cyclist on that street.

    2. It’s interesting to see that Nickerson actually has higher traffic volumes than Madison and 23rd:

      This makes me hopeful that after Nickerson’s road diet successfully proves itself, it will be easy putting Madison, 23rd, and many others on a road diet.

      I emailed SDOT last year about putting 24th/23rd on a road diet and they said they had looked into it, but that traffic volumes were at such a level that too many people would divert off of the arterial and shortcut through the residential areas, so it’s encouraging to see that Stone Way debunked this notion.

      1. If neighborhood diversions are a problem, the key is also clamp down on cut-through traffic by adding traffic calming features to the neighborhood streets like intersection bulbs and on-street parking on both sides.

    3. That would be so nice. I bike home along there every day. They actually are going to do a full-scale reconstruction of it in a few years (its pavement is so bad that it can’t just be repaved, it has to be redone all the way from the bottom) and although they haven’t made any decisions yet it sounds like a road diet is one option on the table. I was thinking, since they are going to do a full reconstruction, how much more would it be to install streetcar tracks as part of that?

  5. This can’t come soon enough to Columbian Way. I second that 23rd Ave South needs a road diet, but I don’t see that happening. Rainier would probably be the best street to go on a road diet in Seattle. I don’t see that either, but imagine all the less accidents occuring? Of course, the city did put it on a road diet from 59th Ave S to the Renton city limits.

    Does anyone have a list from the city of all the streets that have gone on a road diet in the last 15 years? I never heard of a “road diet” before coming to Seattle. Do other cities do this? Possibly Portland? I lived in Phoenix for 22 miserable years which went the opposite way…most streets there went on road “weight gains”.

    1. Kirkland put Lake Washington Boulevard on such a diet way back in the 1980s. My understanding is it works best on streets that are heavier on residential than commercial.

      1. You know Frank, that is true…Kirkland did do that because that was the first example I ever saw. I moved from Phoenix temporarily to Kirkland (while looking for a house in Seattle) and noticed that Lake Washington Blvd through Kirkland was just re-striped to 2 lanes from 4 lanes. Never saw that before!!

    2. It’s coming to Columbian Way this summer! And 15th Avenue South is getting some good changes too, north of Spokane St.

    3. Part of Rainier will be going on a road diet at some point. Part of the “North Rainier” (aka Mount Baker Station area) plan is to divert traffic from Rainier across Bayview to MLK, and have the section of Rainier between Bayview and MLK become a nice main street for that new neighborhood. The zoning plan would allow up to sixteen story buildings in the center of the neighborhood, so that’ll probably be a major urban center in a few years.

  6. Yes, other cities have done these conversions. I know Tucson, AZ has done them. I also believe Portland and Vancouver, WA have also done these. There is a study available on line which was co-written by Peter Lagerwey, SDOT’s former Bike/Ped coordinator.

    Remember that these often are done to both improve traffic flow and safety. The key to making sure that the traffic continues to flow and not go onto neighborhood streets, is to coordinate improvements at the intersections (i.e. signal timing or turning lanes if needed) with the overall re-striping.

    1. Great link! Nice that we’re leading the country in this (Seattle, Bellevue and especially Kirkland).

    2. “Seattle made its first conversion (N 45th Street) in 1972.” I wonder what N 45th looked like back before this conversion. It’s a pedestrian paradise now.

  7. As someone who used Stone Way regularly in my time in Seattle (2001 to 2007) I was first a bit surprised to see the road diet when I was there last month. But it worked – really well, in fact. I used the 16 for the few days I was in town, and it functioned pretty smoothly from a bus rider’s perspective. Definitely a solution to be repeated elsewhere in town.

  8. I would like to nominate the sidewalk-less portion of Cloverdale-to-Roxbury for a road diet, so we can have sidewalks and bike lanes between South Park and White Center… and hopefully a way to bring the stop for the Olsen-Meyer P&R to the side of the road instead of being a 5-minute pull-off loop. Cloverdale-to-Roxbury is essentially the third freeway west of South Park. I think two is more than enough. Bring the traffic down to neighborhood speeds, and we could have crosswalk bulbs to enable moving the westbound Olsen-Meyer bus stop to the north side of Olsen.

    The county is planning to add bike lanes along that many-named road, so now is the perfect time to put that road-of-many-names on a diet.

    We’re going to need some help reducing congestion on the 1st Avenue Bridge one way or another.

  9. The road diet on Fauntleroy Way in West Seattle has been great. Much more safe and comfortable to drive on. The four lanes were always scary with all the curves.

  10. Mike: they did I-5 in the Carter years with the 55 mph speed limit.

    of course, Stone Way North is safer; they slowed it down and confused the drivers at the north end of the restriping.

    Madison Street on First Hill was put on a diet in July 1994.

    what is missing from the SDOT analysis and this discussion is the effect of the three-lane profile on transit flow. without bus bulbs, each bus stop becomes a bus trap, as buses have to wait longer to leave the zones with a steady stream of traffic in the single lane.

    to some degree, SDOT practices planning by modal silos; they produce a freight plan, a bike plan, a ped plan, and a transit plan. some arterials are named for priority in multiple plans. that was the case with Nickerson Street.

    on some arterials, transit flow is important enough that SDOT should consider a profile that takes away some parallel parking. McGinn has mentioned this. 23rd Avenue East is a key transit arterial. perhaps bikes should have priorioty on a parallel arterial.

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