A new report by the city’s transportation department (SDOT) finds that “rechannelizing” Stone Way North in Wallingford—essentially, adding a bike lane in the uphill direction and a shared-lane marking, or sharrow, on the downhill side—has made the street safer for drivers, pedestrians, and bicyclists. The change to Stone Way, like a similar change currently being considered for W. Nickerson St., was opposed by businesses who said it would lead to paralyzing traffic and clogged neighborhood streets in the area.
Instead, SDOT found, exactly the opposite happened:
• 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 40 mph.
• 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.
What are the implications for future “road diets” like the one proposed for Nickerson? Fans, like Mayor Mike McGinn, will certainly see the latest study as good news—more evidence that if you add bike lanes and pedestrian-safety measures to a road, traffic doesn’t slam to a halt as a result.
For detractors, like businesses around proposed road diets, no amount of evidence is likely to be enough. Just this morning, North Seattle Industrial Association president Eugene Wasserman announced the formation of a new “15th Ave. W Transportation Coalition” dedicated, among other things to “protect[ing]” Nickerson “as a route to I-5 and the north portal” of the new Alaskan Way deep-bore tunnel. “Any proposal that reduces the carrying capacity of Nickerson is unacceptable.” Even, it seems, when it doesn’t.
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Great news. And a good reminder why voting out Greg Nickels was a wise move.
Next Nickerson, then Westlake, then 23rd/24th, then Eastlake, then…
Don't forget possibly the most impressive finding of the study – peak hour capacity has been maintained on Stone Way: the corridor has sustained its capacity to carry the same number of motor vehicles in spite of the reduction in the number of general travel lanes.
Wow. So road diets can retain existing car (and freight) capacity, make for safer pedestrian crossings, encourage drivers to go the speed limit, and reduce vehicle crashes? Sounds like a win-win-win-win to me.
The Rainier, Stone Way, and Fauntleroy road diets all were implemented under the Nickels administration, so WTF are you talking about?
How can you claim that the reduction in lanes on Stone Way did not reduce capacity, when vehicle traffic fell by 15% at 48th Street? That sounds like a “reduction” to me.
The study also states that rear-end collisions increased by 65% after the number of lanes was reduced.
And, where is the most important information: trip times? How did this reduction in lanes affect trip times on Stone Way, particularly during peak hours?
Nickels backtracked on the Stone Way road diet, due to pressure from Suzie Burke. It was citizen activists that got it fully implemented.
Clearly eliminating a lane reduces the carrying capacity of cars, but that's not the point. The main argument against road diets is congestion which, as you point out, can be measured in terms of trip times. However, it can also be measured in terms of average speed, which was reduced (in the 85th percentile) between 1 and 3 miles per hour. Since the part of the road in question spans 1.2 miles, according to this math trip times increased by well less than a minute.
Even if this math is somehow way off and trip times increased by 2 minutes (gasp!), it seem pretty callous to argue that it's not worth reducing the total number of accidents by 22 and the number of injury accidents by 17! The study mentions a few theories for why the number of rear-enders increased, but it's obviously a worthwhile trade if the total number of accidents and the number of injury accidents both decreased substantially.
You're confusing two different concepts here. The study shows that Stone Way is still able to handle the peak capacity of cars, which is different than how many cars actually used the roadway (which could be due to a number of factors independent of the road itself). In other words, Stone Way is capable with its current configuration to still maintain the throughput of vehicle traffic that it previously did, but in a more efficient way (because now pedestrians can more safely cross the street and bikes are accommodated without affecting motor vehicle capacity). The fact that average daily traffic declined is partially due to the timing of the study (recession, which saw traffic decline at a similar rate throughout the city).
You're right that you identified the one (out of nine) type of collision that did increase, but every other type of collision stayed static or declined, which resulted in an overall decrease in collisions along Stone. That, and taking into account that vehicles aren't speeding as much along the road, is a positive sign that the street is now safer for all of its users.
Sorry to hear that the most important study criteria for you is trip time (as opposed to pedestrian safety, reductions in collisions, etc), but you might want to turn to page 3 of the study that shows that travel speeds have declined so that drivers are more prone to actually going the posted speed limit – as opposed to speeding. That's a positive in my book, even if it means that folks travel times are a little slower (but still above the posted speed limit).
ivan-
You know that you were one of the most ardent Vashon opponents (VMICC Transpo Committee represent!) to the Fauntleroy road diet. So, as a retrospective is it causing the mayhem that you predicted?
I'm glad we got enough islanders to get you folks to rescind that letter you wrote to Nickels. It made the difference.
Can someone explain how you can remove lanes without decreasing a road's capacity? I'm pretty sure that's nonsense.
Also, without anything resembling a proper control condition, this data is full of ambiguities. The entire city has experienced a reduction in traffic, regardless of bike lanes, and the most obvious explanation is the economy. The reduction in speed is likely due to the reduction in commuting drivers, and of course, a reduction in collisions would follow from any reduction in traffic.
One conclusion that does seem reasonable – the bike lanes and sharrows have at least concentrated bicycle traffic onto Stone Way. It would be interesting to know if it increased overall bike traffic, but that's impossible to tell.
I'm all in favor of bike lanes and sharrows, but I'm also in favor of an honest, intelligent, and objective treatment of this subject matter.
Obviously it reduces the road's capacity in some abstract theoretical sense, but that's not actually relevant. What is relevant (even if you take the one-sided cars-are-the-highest-priority standpoint) is the effect on congestion/travel time. Who cares if the capacity decreased if it was unused capacity that was lost? As the study points out, in some locations peak motor vehicle volume actually increased slightly. Since the speed in the 85th percentile only decreased by 1-3mph (depending on if you are going uphill or downhill) and volumes were able to increase in some cases, the road is clearly not at maximum capacity — no congestion, no appreciable increase in travel time. So who cares if the capacity was decreased?
You are certainly correct that the volume and control of the data has much to be desired, but the data that is there (collected over several years) shows clear trends. However, I believe that the decrease in cars and the increase in bicycles on Stone Way are noticeably sharper than in the rest of the city
As far as the speed change — I don't see how reducing the number of cars on a street would impact the average speed, unless it was in the upwards direction due to less congestion or something. I suppose you could conjecture that more drivers implies more commuters and commuters generally drive faster, but both of those are pretty baseless conjectures without some evidence to back it up (and I certainly haven't seen any).
Regardless of whether this single action increased bike traffic (which I agree we don't have a good way of determining), I think it's pretty self-evident that a civic pattern of creating safer lanes for bicycles will encourage more bicycling in the long run.
In any case, recall that the main point of a road diet is increased safety, not increased bike ridership or improved traffic flow. I say this without a study to quote as evidence, but I'm pretty sure that the city-wide change in collisions over the past few years that may be attributable to the economy causing fewer people to drive does not approach the -14% that we see on Stone Way.
Uh, Oh…..The Seattle Second Guessers don't agree with the results. Thus, the City of Big Thinkers will probably have to stop trying things like this.
When everyone thinks they are smarter than everyone else, all you end up with is a whole lot of nothing.
It's a simple report but report glad SDOT prepared it. Relatively cheap fixes like this can really improve pedestrian safety. Also interesting tidbit from a recent presentation summary about data from Denmark (in 2009 there were 5 traffic deaths in Copenhagen):
I’m guessing it feels more annoying to drive a 20 MPH, but it actually results in fewer crashes, fewer injuries, fewer deaths.
It made no difference. SDOT (Slow Down Our Traffic) and the odious Eric Widstrand were determined to shove the Fauntleroy road diet up our asses come what might. I use 35th now, where I can go 35 miles an hour.
Adding to [Ben]'s great response, think of a water pipe. Imagine you have 1/2 inch pipe going to a 2″ pipe going to a 1/2″ pipe. Removing that 2″ pipe and replacing it with a 1/2″ pipe won't just not decrease flow, it will actually increase flow due to decreased friction.
In this case the fat pipe is Stone Way, and the skinny pipes are the intersections at both ends, which is really the cause of any traffic. We just matched the road capacity to the intersection capacity a bit better.
Or look at Nickerson. The only time there is traffic there is when one of the bridges is up or if there's traffic on 15th. You could have 40 lanes on this stretch, but you won't get there any faster if a bridge is up.
The number of accidents decreasing can reasonably be attributed to the overall decrease in number of vehicles – it is not necessarily due to reduction in number of lanes. The study mentions this.
Trip times? This is more important than people's lives? Your priorities are out of whack.
Erica, there's an odd typo here:
“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 15 PERCENT.”
Love your work!
It depends on the amount of traffic, that is true. There are intersections along Stone Way — not just at each end. If the lights at each intersection stay green for a set amount of time, you can get twice as many vehihcles through each intersection during one green light with 2 lanes as with 1 lane in each direction.
So, if there are more cars than can get through an intersection in one green light in one lane, then some cars will not make it through that intersection in one green light, whereas, if there were two lanes, all cars could make it through that intersection in one green light.
This is a major question to me: are there so many cars in peak hours lined up in each single lane at interesections that not all of those cars can make it through that intersection on one green light? If so, then having only one lane in each direction, instead of two, is making traffic worse, and increasing trip times. This would not necessarily show up in “speed” of traffic measured at some single point along Stone Way.
The water pipe analogy does not hold water (pardon the pun) in this case. There are not just intersections at each end of Stone Way — there are around a dozen intersections, and many parking lots, along Stone Way, between the intersections at each end. So, there are mnay places along Stone Way, where vehicles enter Stone Way, increasing traffic volumes, such as Bridge Way N., N 40th, N. 45th, etc.
Also, if there are long lines of vehicles in each single lane, then it would be much more difficult to enter Stone Way from a parking lot, or at an intersection with stop signs, than it would be if there were two lanes in each direction, with shorter lines of traffic in each lane. How is this being measured?
People's priorities are their own damn business, not yours. If safety was REALLY the issue, SDOT would install pedestrian-operated stoplights.
I know… funny how revisionists pretend none of these improvements happened until Nickels was voted out, when in fact his administration's active efforts to improve bike/ped/transit facilities were a key reason they managed to happen.
I didn't like the guy and a big part of me was glad when I saw he wasn't going to get re-elected, but a lot of credit for the city's improvement for biking/walking/etc goes to the guy's administration.
You asked how you can remove lanes without decreasing capacity, I answered. Yes, it's more complex than a straight pipe – it's a network of pipes. But if this length of pipe isn't the bottleneck, then you don't decrease capacity.
You can argue about not making lights or entering from parking lots or a dozen other issues, and I could debate the other side (I've never missed a light there; parking lot traffic is a very small percentage of traffic flow, plus there's at least an opening every light). And business owners in the neighborhood were afraid of all of your arguments. But in the end, we have real data about the results – and the results are great!
Add to that anecdotal evidence – I drive that path frequently and haven't noticed the slightest change in traffic patterns.
I think it's pretty self-evident that a civic pattern of creating safer lanes for bicycles will encourage more bicycling in the long run.
That's certainly the theory behind the bicycle master plan. However, it's not self-evident to me that safety is a primary factor keeping people off their bikes. Back when I had a commute, the main factors for me were schedule, weather, and the degree of laziness I was feeling that morning.
Perhaps I'm in the minority, though, and it would be interesting to see some data that clearly connects safety with increased ridership, especially as we're asking for money for the BMP. These data hint at such a connection – perhaps there are some additional ways of looking at the entire data set that could strengthen the case.
I'd really like to see a similar report for 24th NW in Ballard. There are parts of that diet that feel like they drasticically improved certain stretches of that road, but there are other areas, where it feels much more dangerous than before. I'm not sure they've gotten it right on 24th, and would like to see some technical reports before and after.
“it feels more annoying to drive a 20 MPH” Personally, I'd rather drive the highest average speed, provided it requires fewer stops, even if that number is low. I'd much rather go 20 and seldom brake, than to occasionally top out at 50 and stop and start stop and start. I think one of the rare joys of driving is getting into the rhythm of the lights on a major boulevard like 15th where I might only be going 35 mph, but never hit a red light.
Well, it worked in this case and there are probably a latticework of contextually related reasons that it worked, which may not be the case for many other roadways. So just in case you or anyone else gets the idea, let's not start planning road diets for every 4 lane arterial in Seattle. It works in some cases but not every case.
(And TBH I was pretty sure it was going to work here. This is not a prime or heavily trafficked arterial.)
“How can you claim that the reduction in lanes on Stone Way did not reduce capacity, when vehicle traffic fell by 15% at 48th Street?”
Yeah, a more accurate way to put matters is that traffic patterns adjusted to the marginally reduced capacity… not that capacity wasn't reduced.
This is very promising, and not unexpected. I am glad they are being forthcoming with the data in this manner.
Why no truck counts though? Wasn't this the main argument against this effort? If indeed there was no real impact, truck counts should stay within a margin of error based on the original count.
This was a good change for Stone Way, and a good case where a road diet helped a corridor. While still difficult for pedestrians to cross between 34th and 45th, even at the traffic signals (due to swift and often pedestrian-negligent left and right turns), it's now much easier to watch out for 2-3 lanes of traffic to clear instead of 4 quicker lanes when crossing.
And then Ivan would complain about the cost and use of pedestrian-operated stoplights. Automobiles are a constitutional inequity.
Standy's Furniture located on Stone at 35th since 1986 is now out-of-business. The tool rental and sales store across the street is empty. Business on Stone Way is hurting. The road diet didn't cause it, but closed businesses will reduce traffic.
We'll see what it looks like when, hopefully, employment returns.
Any chance CBC salts the bike results?
Wrong again, Wells. Pedestrian-operated stoplights are effective because they are unambiguous. Red light means STOP.
While it was a win-win-win in this case, maintaining car traffic capacity is not (and should not be) the goal of road diets. The report puts it this way: “To improve safety and mobility, Seattle will increasingly rely on transportation modes such as bicycling, walking and transit. In order to complete the city’s bicycle and pedestrian network, motor vehicle lanes must often be removed to create space for bicycle and pedestrian facilities (often referred to as a “road diet”).”
Roads like Stone Way or Nickerson are the cheap and easy ones. Prioritizing non-SOV traffic on heavily used roads will be much harder.
SDOT road diet study was an incomplete unprofessional study which basically shows if you have less cars you have less accidents. Big deal. Those cars who formally were on Stone Way merely went somewhere else, where additional accidents occurred.
SDOT data collection refuses to look at accidents that are not on police reports. So minor accidents are not recorded. Businesses who are on Stone report many more bicycle accidents than SDOT acknowledges. These reports are from businesses who bicycle to there business.
Erica, you would not accept such a crappy report from a developer, yet you accept it from SDOT.
What would be nice is more actual concern about bicycle safety and less about reducing car capacity.
Road diets work because they move traffic more efficiently. They have been especially successful in areas that have many access (driveways) along the corridor. Seattle has been doing these, and other “traffic calming” measures since the 1970's.
The reason “less” lanes moves more (or the same amount of) traffic is the addition of a center turn lane. This allows turning vehicles a space for refuge as they turn accross the road to/from a driveway (as oppposed to stopping in traffic, and waiting for a gap to turn).
Road Diet roads are also safer since the speed of traffic is “controlled” by slower moving vehicles (rather than faster vehicles using another travel lane to go past slower vehicles).
They are a smart approach in built-up areas, and the space gained by removing the two extra travel lanes (and adding a center turn lane) can be used for bike lanes, pedestrian enhancements, etc..
But to say they somehow limit, or discourage the use of vehicles doesn't really apply.
As the data shows, they still support about the same capacity, and in some instances can support more.
Wait, we're talking about 35% more bikes, 75% drop in speeding, neighborhood traffic was reduced, 33% fewer injury-causing collisions, and 80% fewer car-pedestrian collisions.
And you think this is all explained by a 6% decrease in car traffic?!?
Just make sure you don't let facts get in the way of your opinions.
I would think that other things are unambiguous and should also be effective:
Pedestrian in roadway = do not hit
Bicycle in roadway = do not hit
Car in roadway = do not hit
Pedestrian in crosswalk means stop
However, we have seen that reduced traffic speeds are effective at preventing accidents while keeping traffic smooth (ie not significantly increasing trip times).
Eugene, What the report says is that traffic dropped citywide, so the cars didn't go somewhere else. You say that the “accidents” went somewhere else too. Where did they go?
You know and care very little about safety. You are a paid lobbyist for the trucking industry.
It's worked on a couple dozen roads so far in Seattle.
If we enforced every crosswalk violation, maybe we could afford that.
The Fauntleroy road diet happened and clearly the world hasn't ended, Vashon Island hasn't sunk into the ocean despite John “ivan” Locke's efforts.
Death by a thousand cuts leaves you just as dead as a shotgun blast does. The Fauntleroy road diet made things a little bit worse for 90 percent of its users to benefit 10 percent — if it's even that high.
For me personally, it means that when I have to go off-island to shop, money previously spent in Seattle will be spent in White Center, Burien, and Tacoma.
Agreed; that's why I find it curious why there are those few that love to gun up to the next red light. Momentarily upset about getting stuck behind a turning car or something.
Oops, I didn't mean to “LIKE” this. In fact I think it's pretty off-base. Nickels' “improvements” to bike and ped problems were consistently half-assed. Ever try to walk the “Cheshiahud Loop”? Or ride anywhere near the SLU trolley tracks? His capitulation on Stone Way was just one more case of Nickels being mostly talk and not much action.
I'm going to agree with Eugene here in that the report is quite unprofessional and leaves much to be desired.
Specifically:
- What were the differences in intersection LOS in before vs. after conditions?
- Measuring the traffic along the next 2 parallel local streets is insufficient. Traffic on major arterials such as Aurora and Wallingford as well as cross-traffic (34th, 40th and 45th) could have been reported as well.
- Travel time for all applicable modes could have been collected and reported.
Also, a pet peeve of mine is the statement: “Peak hour capacity has been maintained”. Unless I see intersection LOS output proving this, I challenge the validity of this statement. There is a vast difference between capacity and observed volume which the report seems to confuse.
My skepticism about the report aside, I'm very glad this particular project was completed. I was out there bicycling in the protest rides a few years ago and now it is good to see at least a few positive measures coming out of it as all of us who rode knew would come.
But to fully convince the people who value saving a few minutes at the expense of increasing the chances of injuring and maiming vulnerable road users, these measures should be collected. It would be pretty morbid, but it could be possible to express people's value of time in terms of increased chances of injuries and fatalities to vulnerable road users.
The fact that traffic dropped citywide doesn't mean people didn't move from Stone to another street. Since SDOT only measures a relatively few streets, we don't really know if other streets increased. Burke seems much more crowded.
Given that we have a citywide recession and less people trying to get to work on time, it wouldn't be surprising that accidents fell citywide, but that some that would have happened on Stone happened elsewhere.
Yeah, I'm not going to argue the City's improvements under him didn't need… uh… improvement. But he got the ball rolling on a lot of things that past administrations never even considered moving forward on. His willingness to not only humor the subject as Mayor but open the door for these projects is a big reason we can even discuss the implementation of a lot of this stuff.
Name them.
Peak-period speeds indicate that there are not substantial backups.
Yikes, it would be fascinating data but all that analysis and every project would cost more than Mercer!
As much as I like to see road diets (and more street space for people) everywhere, Nickerson is a freight corridor. How does that change the equation for success? Aren't turning trucks the largest source of bicycle/vehicle crashes? And isn't the ship canal path just a block away? Nickerson may not be the best candidate for our next road diet project.
shhh! you'll piss off the unliked, unwanted, unofficial burgermeister of the center of the universe. protect ya neck, kid.
That's an interesting question. According to a study here the biggest source is actually driveways, but it's only 5.1%:
http://www.tfhrc.gov/safety/pedbike/ctanbike/ct...
But again the important thing is that accidents are likely to be less serious at lower speeds, and currently Nickerson traffic exceeds the posted speed limit–often more than 10mph over. Nickerson does lead to I-5, but that's not a reason for unsafe highway speeds.
No, not really, it's not that hard.
For intersection LOS, one needs to obtain intersection geometry (which can even be obtained via google maps), signal timing, vehicle turning movements (and if you're really gung-ho pedestrian crossing volumes) and then plug the numbers into any standard traffic software program and viola, you have intersection LOS.
Travel times require an intern, a vehicle and a stopwatch. Done and done.
Other vehicle volumes are tracked anyways according to this map: http://www.seattle.gov/transportation/tfdmaps.htm Also, if SDOT keeps an annually updated traffic model it shouldn't be hard to extract the flow of vehicles as well.
If this were a corridor study or any other infrastructure upgrade study you can bet there would be plenty of intersection LOS analysis. Why it wasn't included in this study is something that still baffles me and leaves it open for people to question the validity of the report. Do your due diligence, SDOT!
Uhm, there is really no way you can conclude this based on the data presented in the report, and especially not from the speed data. That is one of the major holes of analysis in this report.
Without intersection LOS stats, SDOT hasn't provided the full story.
To those interested in the Nickerson St. Road Diet, I am starting up a group to support the effort to get it completed. If you're interested in knowing more or being involved, please check out http://groups.google.com/group/Nickerson-road-diet
I'm just one person who just started getting the word out so there's not much there yet. I'd love the help of anyone willing to be involved.