Saturday, April 1, 2017

Fixing Seattle's Traffic Mess

Seattle's traffic has steadily worsened during the past ten years, with much of the city heavily congested during the extended commuting periods.   A number of national surveys suggest we are now one of the top five worst traffic cities in the U.S.

Traffic is now going critical, changing the way we live, wasting a tremendous amount of time and fuel, and will soon cause Seattle's decline as a viable place to work and live.  As someone concerned about global warming, reducing the fuel-wasting traffic is an issue I care about.

Some of these problems are due to the growth of Seattle and our geographic restraints, with the city surrounded by water on two sides.   But a significant part of our traffic woes are unnecessary, the result of misguided and problematic decisions over the years.

This blog will examine some of the problems and what might be done to address the growing grid-lock of the city and region.

The Current Situation

One can get a good idea of the situation by using the historical traffic maps available on the google maps website.  Below are the average traffic summaries for 8:25 AM (left) and 5:30 PM (right) for Wednesdays.  Green is free flowing, while reds indicate serious traffic.  For both commute times, the main freeways (I5, 520, I90) are heavily congested (red) and most of the major arteries in the city are slow (orange).   You can click on the images to make them larger.   Of course, this is the average traffic; when there are accidents and construction, the situation can get much worse.  And because

most of the arterials are already slow, the system is not robust or resilient, i.e., there is little spare capacity on arterials to pick up the slack when a major road is clogged by an accident or construction.

Major Problems

1.  Road Diets

During the past decade, the city has drastically reduced the traffic capacity of major roads throughout the city, such as Rainier Avenue, Nickerson St, and NE 125th. Such "dieting" often took four lane roads, with two lanes in each direction, and altered them with one lane in each direction with a turning line between them.  The city did this to slow down car speeds, reduce accidents, and to create bike lanes on the sides.

There is no doubt that road diets cut down on accidents, by slowing traffic and reducing opportunities for lane-change accidents, but they reduce the maximum throughput of a road and force all traffic to move at the speed of the slowest vehicle.  A good example of the bad effects of road diets is NE 125th.   Before the lane reduction, it was one of the fastest ways to move east-west across north Seattle, but after the diet, the traffic often gets very slow during commute time (I have experienced this personally).   Google maps at 5:05 PM on an average Thursday shows the congestion clearly, with slow traffic from Lake City Way to Roosevelt Way, where the diet ends.  Bad diet.

I could go through the other Seattle road diets with you using google maps, but the conclusions are the same:  dieting has promoted congestion and substantially reduces maximum throughput of the road.   Just as small blood vessels can assistant blood flow when major arteries feeding the heart are clogged, preventing a heart attack, road arterials with excess capacity stand ready to take over some of the traffic load when major roadways (like I5) get clogged.   And Seattle is deliberately reducing this valuable resilience.  A big mistake.  

Worse than that, some in Seattle want to do more of it.  One road that is still often running realitively freely is Sand Point Way NE (see google maps above), a road providing a fast route from NE Seattle to the UW, Children's Hospital, Magnuson Park, and the city.  There is now a proposal to put Sand Point Way NE on a diet, described here.  If you don't like the idea, you might email the Mayor or the director of the transportation operation division, Mark Bandy ( .   I have emailed Mr. Bandy and he seems interested in feedback.

So recommendation number one is to reverse the road diets and stop doing more.

2.  Poor Road Conditions

Many of the roads in Seattle are in very bad shape, causing cars to slow down and tires to fail.   Bad roads discourage bicycle commuting and are extraordinary dangerous for those cycling for commuting or recreation.  I did a blog on potholes...they are everywhere.  Seattle can find millions for silly bike rentals, ineffective streetcars, and other frills, but can't keep its roads in decent shape.  

Seattle Pothole Map
A Washington D.C. research firm, TRIP, found that 45% of Seattle's roads were in poor condition and our roads were the 12th worst in the entire nation.  It might be nice if Seattle Council members paid more attention to the traffic-producing bad roads than kayaking out to oil platforms destined for Alaska.
A major intersection near Northlake and Boat Street has remained in axle-breaking condition for years

3.   Too Many Openings of the City's Bridges

Seattle has a number  of bridges that are opened for boat traffic.  But when the bridges open they can (and do) cause massive traffic jams, delaying hundreds of cars and buses and sometimes thousands of people.  The bridges do not open during central commute time (7-9 AM, 4-6 PM) but Seattle commute time extends way beyond that in Seattle (more like 3-7 PM) and traffic is heavy outside of the commute period as well.  These bridges open a lot--5500 times in 2016 for the Fremont Bridge, for example.   Often a bridge opens for a single sailboat.  Does it seem reasonable to mess up traffic for 15 minutes or more and inconvenience hundreds of people (or more) for the sake of pleasure sailing?  I don't think so.  For the University Bridge, the traffic sometimes extends 1/2 mile north to University Village. 

Non-commercial traffic should not be able demand bridge openings at any time.  Perhaps there can be three openings between 6 AM and 9 PM each day (say at 9:30AM, 1:30 PM, and 7 PM).  The Coast Guard controls the waterways, so the City needs permission for such restrictive openings.  If the Coast Guard is not reasonable, the City should ask for the help of our representatives in Congress.

4.  Sounder Trains:  Too Few and Unreliable

Seattle and the Puget Sound region desperately needs rail service to move folks efficiently around the urban corridor.  In addition to the slowly growing light rail system, there are the Sounder trains that run on commercial rail tracks.

These trains only run during commute times and there are no weekend trains.  There are a relatively limited number of departures.  But a real issue is that mudslides often cause several-day train cancellations between Edmonds and Everett.   This problem has been going on for years, with the problem limited to a mile or so stretch with bluffs near the train track.   You would think that in this modern age we could figure something out--stabilize the slopes or move the track towards the Sound. With infrequent departures, lack of reliability, and perhaps lack of organization/PR, the Sounder trains are often half full or less.  Something is wrong.

4.   Increasing Accidents from Connected Drivers

Traffic accidents are increasing nationwide and our area is not immune from this trend.  One accident on I5 can inconvenience and delays thousands or tens of thousands of people.  There have been a number of studies suggesting that drivers playing around with smartphones and other electronics is a major contributor to the recent uptick in accidents.  How many times do you see folks texting or dialing phones while they are driving?  I do all the time.   How often do YOU do it?

Seattle and the State of Washington needs laws that will make texting or dialing a phone or putting in navigation information, either directly on a phone or through the car's electronics, illegal while the car is in motion or waiting for a light, with a very substantial penalty.  Could drivers be required to provide their phone for inspection after any serious accident?    Laws to restrict electronics use while a car is in motion would save lives and clearly help the traffic situation.

5.  Fix the Sound Transit Light Rail Achilles Heel

There have been many stories in the media about the surge of ridership on the Sound Transit light rail system and the complaints that it is being built at a glacial pace.  But there is something that has not been talked about much, the achilles heel of the system...the street grade part between Seattle and the airport. It takes forever to travel that segment and sometimes the trains get into accidents with cars.  Some folks refrain from using it because of this slow segment (driving takes half the time or less)

So why not fix this problem?  Run a fast spur line from downtown to the airport using the I5 right-of-way?  (see illustration, the red line is the addition) The cost should be modest and it would substantially shorten the trip for those coming from the airport and south Sound.

A major mistake for Sound Transit's light rail is the lack of parking at the stations.  Folks need a place to park if they are going to use the train (many either don't want to use the bus or don't have a convenient feeder bus route).  There IS one station with lots of parking:  the UW Stadium station.   I was shocked that light rail parking wasn't planned for that location--in fact, there isn't even a place to drop folks off or wait to pick them up.  A major deficiency.  But it is not too late--the UW has a huge lot, much of it empty, and an entrance could be created from the NE (by the driving range).  One can park at the huge UW lot for $6.00, but a lot of folks don't know that.

The University Station is not car friendly.....a mistake.

6.   Dangerous conditions on bicycle commuting routes

I commute by bicycle.  While there is a lot of talk about the importance of bicycle commuting, major routes such as the Burke Gilman trail are not properly maintained, with root heaves, holes, cracking asphalt and other threats.  There is no safe, totally protected route into the city from the north.  The only safe way to commute is to be totally separate from cars, not the side lanes of the "road diet" streets.

There are a number of other problems I could talk about, such as continuing lack of bus service, but the above represents a start.  Let me end by noting that some out-of-the-box vision and leadership is needed for Puget Sound area transportation.  Here are two ideas:

1.   Seattle is surrounded by water and commuter ferries...a modern version of the old mosquito fleet... could have a major positive impact.   Impact a boat that went from Lake Union to Ballard to the UW, the Magnuson Park (lots of parking there) to Kirkland, then Madison Park, and the back to Lake Union?  It would be heavily used.  Other boats could go to Edmonds and Everett, or down the Sound towards Federal Way and Tacoma.  Another could go from Lake Union to Bellevue and Renton.  San Francisco has the Sausilto Ferry--we could do much better than that!

2.  Big buses going down major arterials are ok for a start, but you need go the last mile between home/office.   Why not use small vehicles (even cars) to pick up real-time, on-demand car pools or ride sharing?   Uber and Lyft are already experimenting with ride sharing in some cities.  So if it is 9:30 AM and you want to ride to the University light rail station, just use your smartphone app and you could choose between your own ride or ride share.  Perhaps Metro could pick up your first 5 rides a month.

3.  The city and the region needs to be much more aggressive with adaptive signal timing, which controls light change frequency and duration based on actual traffic conditions.  This "big data" approach to traffic management has proven to be very effective when tried elsewhere.    First place to try  this should be the "Mercer Mess", in which the traffic has gotten worse with the large number of lights, many of which are poorly timed.  There was some talk of doing this, but haven't heard much about it lately.

The bottom line is that increasing traffic and congestion is not written in stone.  There are a lot of inefficiencies in the current approach and a lot of creative ideas that should be considered.


Help Determine Local Impacts of Climate Change
Society needs to know the regional impacts of climate change and a group at the UW is trying to provide this information with state-of-the-art high resolution climate modeling.  With Federal funding collapsing, we are experimenting with a community funding approach.  If you want more information or are interested in helping, please go here.  The full link is:


TheWildLine said...

Population control isn't an option in the US until runway global warming takes control.

HunterZ said...

Ironic that you mention the Sounder as being part of the solution. They put a Sounder station right between the two main arterials (James & Smith) that connect East Valley and West Valley highways, such that whenever the Sounder rolls in the heart of the Kent valley gets cut in half. Since the Sounder mostly rolls through during commute hours, you can imagine the mess this creates for commuters; all of the downtown Kent area gridlocks, with hundreds of cars stretching for almost a half mile in every direction.

It's also dangerous, as tons of pedestrians weave their way among the frustrated vehicles when walking to/from the Sounder station.

To top it all off, the City of Kent has no clue how to time traffic lights, so once the Sounder does manage to crawl away, it still takes 10-15 minutes for traffic to start clearing out - which is just about time for the next Sounder given that they run in both directions and each direction arrives every 20-30 minutes.

Traffic is bad everywhere though: The S I-5 to N I-405 interchange backs up all the way to Boeing Field during the evening commute, in no small part because it's one regular lane and one HoV lane. SR 167 backs up in both directions for similar reasons - HOV lanes cram increasing traffic into only 2 lanes through major chokepoints such as the I-405 interchanges. Maple Valley Highway (SR 169) backs up for miles in both directions due to badly placed/tuned traffic lights and stretches of only one lane in each direction - a problem that will get significantly worse once Black Diamond completes its plans to add 6000+ new homes in a couple years.

Unknown said...

Amen about the bridges. I have been a driver and a skipper. The Fremont Bridge opens once every 15 minutes on average, quaint but insanity with 1000 people moving into the city weekly. The Ballard Bridge opening for one pleasure boat seems nuts too.

Thank you for bringing this up. Is it the Coast Guard we must contact about this? IMHO there should be no openings from 3-7P and 6-9A.

Magnolia, where I live, has become an island with the road diets and the already challenging east-west options. If you take care of the disabled and/or elderly and cannot use public transportation it is a nightmare to get anywhere on time. I was taking a class at the UW at night and it took me over an hour to get there from Magnolia---even on the #31 bus.

-A lifelong Seattle resident (mossback)

Amish Cyborg said...

I'd expect more from a scientist than anecdotal evidence to back up claims of increased traffic. Fortunately, traffic delays and throughput are quantitative things that can be and are measured. Traffic studies done years after implementation of road diets on Nickerson, 125th, and 75th found that they all greatly reduced speeding, collisions and fatalities while maintaining or increasing throughput of traffic. It shouldn't be surprising that when you reduce accidents and allow cars to turn left without clogging up the street, you improve traffic flow. There's a whole discipline of engineering dedicated to this, and there's substantial evidence that this street design is the most efficient for in-city, mid-size arterials.

I also have to bristle at the idea that public safety should be of no consideration in urban design. If we can make streets substantially safer with virtually no time penalty to drivers, we should do it. These road diets legitimately save lives, and they make cities more accessible and comfortable for pedestrians and transit riders, all of whom have just as legitimate a claim to publicly-owned streets as do drivers.

I'm not even sure where to begin with the rest of this:

Potholes are a legitimate issue that have a tangible adverse economic effect on cities, but no urban planners or traffic engineers seriously regard them as a primary cause of traffic. They break cars and are expensive to fix, but they don't measurably decrease throughput of roads.

Sounder trains run on private freight rail lines owned by BNSF. They have no control over maintenance and certainly don't have the power to move them. The reason they run so infrequently is because BNSF limits their number of daily trips, and they're incredibly inflexible. They just added two additional trips on the South line and it took years of negotiating.

The at-grade stretch of light rail along MLK is absolutely to blame for some of Links's worst problems, including limiting headways on the entire line to six minutes, but building seven miles of bypass track certainly wouldn't be "modest." At the rate Sound Transit builds elevated rail, that seven-mile stretch would cost about $2 billion (probably more, since that stretch of I5 is mostly elevated and carved into the side of an extremely steep hill).

There have been entire books written about the detrimental effects of parking around transit stations, but I'll sum it up by saying that building parking is just about the worst bang for the buck that a transit agency can possibly get. Each spot in a park-and-ride costs $80,000 and allows for 1-5 people to use transit at a time. Parking around stations reduces all other means of access, makes transit much more expensive to operate, makes adjacent housing much more expensive, and reinforces auto dependency. In difficult-to-access areas like Angle Lake, there's a legitimate need for a reasonable amount of parking, but massive garages have no place in a city. And if there is demand for parking, the market will supply it. Private landowners can build lots near stations and taxpayers won't have to subsidize it.

jayemarr said...

It's nice to see Seattle's hostility towards automobiles acknowledged and even criticized. People who visit here from other parts of the country are horrified by the state of our transportation system, and the people in charge seem to feel this is a good thing. It really isn't. For one thing, all those cars puttering along at 5mph are generating a tremendous amount of needless pollution.

Unknown said...

Wow! Excellent post, and I agree entirely with every single point. Let's quit wasting money on each politician's pet projects and spend what limited resources we have wisely. Cliff, you had written a previous post in the past about dedicating an entire thoroughfare/arterial for bicycle traffic. Maybe you could repeat it again in today's post to your blog. Why mix bicycle and automobile traffic together? It only adds to the danger and confusion of getting around town. Ever try driving on Broadway lately, with all the different lane markings for autos, bikes, and the streetcar? Too confusing for me.

Brendan said...

Amish Cyborg is right. I've been following seattle transit blog for years learning about transit, and it's absolutely misguided logic on Cliff Mass' part here. Road diets aren't the enemy, the analogy to arteries is just wrong. Bigger is better, right? Wrong. It's actually more complicated than that.

Park and rides aren't going to reduce traffic, Cliff. How terribly misguided. The space you waste with parking spots obliterates hundreds of times more efficient space moving people on buses or the sidewalks, and is just bad urban design. It actually exacerbates all the problems you think they would solve.

I'm sorry to say it, but perhaps you should do some reading.

jayemarr said...

To the people suggesting that building parking around train stations being a waste of money -- I respectfully suggest you have no business asking for my money to build a train station I cannot use, much less forcing me to pay for one, which is what taxing people does.

Kenna Wickman said...

Over here in Kitsap County and I imagine elsewhere around Seattle there are merges where one lane is almost entirely unused while the other lane jams up. Coming off of the ferry in Kingston, and the Highway 3 merge in Bremerton just south of Auto Center Way are the two that stick out in my mind. In Kingston eventually everyone has to move into the right lane. I have noticed this as well at the south opening to the Express Lanes on I-5, and at the northbound Hwy 16 merge on I-5.

So instead of zippering at the merge point which seems to be the best way to do things, everyone starts merging right just off the ferry, leaving some 4-5 blocks of roadway entirely unused. Its worse in Bremerton. People start merging left about a mile away from the merge point and a lane mile of freeway is unused while cars are backed up that mile, especially soon after the shift change at Bangor.

I use these unused lanes. This seems to anger the people who aren't moving in that other lane and I've even had some drivers threaten me with hand gestures. Some think its being rude. I think its being efficient and it saves me fuel and frustration.

Thecatguy93 said...

@Amish Cyborg-

You raise some legitimate points, but I disagree wholeheartedly with one thing you said. Transit riders, pedestrians and bike riders do NOT have just as legitimate a claim to the roadways as car drivers. I can't recall a single pedestrian or bike rider with a license tab on their back. Have you noticed the price of licensing lately, and the associated fees? We(car drivers) are the ones paying to maintain these roads, make bike lanes and generally to keep those people safe. When bike and transit riders who forgo having a vehicle start paying licensing fees for their use of the roadways, then we can say they have just as legitimate a claim. Until then, cars are king of the road.

showhank said...

Kept waiting for the April fools.....

John Marshall said...

Traffic design appears to be as prone to populist thinking and anecdotal evidence as weather forecasting.

As in, everyone feels they have some measure of expertise, but once you get into the science, it's very hard and often non-intuitive. And the real fix isn't politically viable.

I've spent time in cities where every millimeter of roadway is packed with minimum-width lanes, with tires brushing the curb on the right lane and mirrors just missing center divider on the other, and while they might move more traffic under ideal circumstances, they require very high driver skill and no tolerance for goofs. Plus they are dangerous for larger vehicles and absolute death for bicyclists.

Seattle's roads feel much friendlier and more relaxed than in those cities.

LA, which keeps adding lanes and growing highways, doesn't see significant (or sometimes even measureable) improvement when adding lanes, when you'd think the improvement would be immediate.

In many ways, Seattle is like a European city in that its very difficult to solve traffic problems by adding more and wider roads. The way the city is designed, with many waterways and other obstacles. Spend some time in Amsterdam and you'll see one solution (no, it's not the coffeeshops). Think trams and bicycles. Other cities have employed different techniques, many of which involve making it easier to live closer to jobs. No large trucks on city roads during busy traffic periods. Priortizing trains and street cars over cars. In the end, they've mostly taken the direction of reducing the number of vehicles on the roads.

I'm beginning to think that cars in cities are like guns across America. Dramatically reducing either of them is never going to be politically possible. Anyone with a license can buy a car and drive it anywhere they want, any time they want. Land of the free.

Eventually we'll wind up like Bangkok (which I used to frequently visit on business) where allowing 2 to 4 hours to get places was prudent.

But any solution that doesn't start with dramatically reducing single-occupant cars in Seattle is just populist pandering (or at best tweaking), in my opinion.

Cliff Mass said...

Folks need to get to the rail station and many/most are not willing to take a bus to do so for many reasons (time issues, carrying bags, etc). You need to have parking by rail stations....or a fast alternative way to get to them (like ride-sharing)..

Bigger is not necessarily better, but no one is suggesting we reduce I5 to one lane each way, right? More lanes provide more capacity and one lane causes everyone to be delayed by the slowest vehicle. This is not is absolutely obvious to anyone driving on the single lane roads around here...cliff

Arie said...

Road diets work for longer commutes where much of the traffic is heading to a choke point anyway, but sympathize with the locals on Sand Point Way who aren't trying to get over to Montlake and 520. Google traffic data however is more than anecdotal.

I also agree on not building expensive multistory parking garages, but there are parking alternatives that aren't being pursued. This isn't Tokyo where the trains run on time and literally everyone is within walking distance of a station.

However good discussion. We have a city betting on density, rail and rapid transit while many of us in tech see self driving vehicles as the 50-year solution. Most of the weight and carbon emissions of a vehicle today is a result of the safety standards all cars must meet. We'll get to conventional self driving cars first and eventually to new car safety standards with only autonomous vehicles allowed saving thousands of lives a year.

Don't worry there will likely be special courses where we can drive our classic cars circa 2017. For nostalgia sake they may even include a road diet street.

Drummer Hoff said...

I have to agree with Amish Cyborg. When I first read Cliff's post, it seemed more like a pet peeve list than science based observations. Certainly the list includes a bunch of annoying facets to our traffic nightmare, but how much do they really contribute?
I know tolls are generally unpopular, but I believe that unnecessary trips contribute greatly to congestion. If folks really thought twice about driving across town for a trivial reason - thereby allowing commuters and workers a better chance of an efficient drive, wouldn't that be beneficial? Join the soccer team in your own neighborhood instead of schlepping to Tukwila three times a week! Maybe a $5 toll would be an incentive.

Tony said...

Light rail from downtown to the airport takes much more time now
than before when buses went down the bus-lane and I-5.
The subsidized cost of light rail is high and results are poor.

Sherry Culbertson said...

Adding a center turn lane on a road with many side streets does help to reduce traffic congestion: Cars attempting to turn left blocks the lane until it can turn, and in rush hour cars make unsafe darts into faster moving traffic to go around. Adding bike lanes also reduces congestion from bikes and cars trying to share one lane. We shouldn't discourage those who can commute via bike- they help reduce congestion and pollution, cause little road wear 'n tear and often also own cars, paying their fair share. For those who don't also own cars, their contribution to reducing congestion and pollution is more than worth accommodating bike lanes.

As the blogger stated, we are geographically limited, but it's the population boom and the lack of planning for mass transit alternatives based on projected future need that caused this traffic nightmare. Unfortunately it can be extremely difficult to fund projects based on future projections, so we end up funding for current need only so by the time it's constructed, new roads are already out dated. To continue pushing for single occupancy vehicular traffic is short-sighted and unrealistic to achieving any future traffic congestion relief.

Tony said...

My best sources tell me by about 2020 GPS will locate to cm accuracy.
Starting over we can build a car-traffic control system where (self driving)
vehicles can drive nonstop at 60 mph through downtown.
No traffic lights needed and criss-cross with 1 inch separation.
Our pedestrian traffic-control smart watches will buzz us when we can cross safely.
We may have to wait 15 minutes for our time slot to leave
but NO MORE traffic jams and 10x less accidents than now.

George Winters said...

Since this is also a weather related blog, it seems that traffic discussion should also include the goal of CO2 emission reduction. One thing missing from the list of problems is the fact that population growth is combined with increased miles driven per person, and the two factors result in unsustainable growth of vehicles moving on the road. The most effective solutions needs to include a goal of reducing the miles driven per person. The constraining resources are physical space, breathable air, and habitable environment. The desired outcome is moving people and goods (not iron). Looking at graphs that combine annual miles driven, gasoline prices, and recessions, the most effective traffic reduction strategy should include raising gas prices, making high occupancy vehicle travel more appealing, and each of us finding ways to not to drive as much.

For the self-centered person who wants to or needs to keep driving more, the most effective strategy is also to do everything possible to encourage other people to drive less.

For the people who keep worrying about who pays the taxes for streets, remember that most of the money for city street projects comes from property taxes, business taxes, sales taxes and so on. Pedestrians, bus riders, and bicycle riders all pay pretty much the same on average as the car driver, and more in a way, because they are also car drivers, and in terms of wear and tear and equivalent space requirement, they are not currently getting a fair share for their tax dollar.

Amish Cyborg said...

@ Thecatguy93

Car tabs absolutely do not fund road maintenance in Seattle. MVET is a state tax that is designated for specific transportation projects like ST3. Road maintenance and construction in Seattle is done by SDOT, and four percent of their budget comes from gas taxes and the rest comes from property tax levies, the general fund and debt/grants. Everyone who lives and pays taxes in Seattle contributes to road construction and maintenance, and everyone has a claim to publicly owned rights-of-way. SDOT spends a massively disproportionate amount of ifs budget on car-centric projects, and it's not crazy to ask that they consider taxpayers that utilize other forms of transportation. Roads are not just pipes meant to move as many cars as possible; they are the backbone of livable, walkable, and equitable urban environments and should be welcoming to all.

John K. said...

My favorite is the airport rail station.. that isn't quite at the airport! You're left with several blocks walking, staircases, and a pleasant stroll through the parking garage. If done correctly, when the train doors open you should be looking at the check-in counters. What the hell happened down there!?

HunterZ said...

@Kenna Wickman: Yeah, you're *supposed* to merge at the merge point, but Seattle-area drivers somehow universally don't know that. I think it's connected with the fact that drivers already on the freeway don't understand that leaving merge gaps keeps the traffic moving; instead, they tend to group up and have to come to a near stop to let each car merge in, while the merging traffic takes the earliest opportunity to merge out of fear of someone not letting them in.

This reminds me of another issue I forgot to mention: The on-ramp metering lights we have often result in traffic not having any chance to reach freeway speed before having to merge, which slows the entire freeway down as people try to merge on at slow speeds. Additionally, meter lights are often used on on-ramps that don't have enough capacity before the light, forcing through traffic on adjoining streets to jam up as on-ramp traffic piles up behind meter lights (which seem to universally be timed for about 3 MPH).

@Arie: Self-driving cars can't come fast enough. Traffic efficiency will be directly proportional to their market penetration, as they will be able to react more quickly than human drivers, especially if they gain the ability to coordinate with each other and/or traffic signals. I don't think anyone is planning for 100% market penetration any time soon, so self-driving cars will have to coexist with manually-driven cars for an indefinite amount of time. I just hope I live long enough to hear stories of crazy lone human drivers driving the wrong way on I-5 for miles and causing zero damage due to the 99% presence of self-driving cars that can coordinate safe avoidance measures.

And to those championing mass transportation: It will never be viable as long as it takes an hour to get anywhere due to having to take 2+ buses/trains to reach your destinations, with 10-60 minute waits between connections. There's also the fact that it just isn't economical to serve anything but urban areas and major corridors, especially when those areas aren't at least one of the endpoints of a commute. When I lived in Tacoma, I was 70 blocks from school and had to walk 30 blocks to get to the nearest bus stop (but, hey, they were so proud of the fact that it went all the way downtown!). Where I live now, I see way more Microsoft Connector buses than I do Metro/ST ones. I just checked Metro's trip planner, and it would take (no kidding) almost 2 hours to get to work by public transit, when it's about 50 minutes by car, and over 45 minutes of that would be wasted waiting for connections; note that this also doesn't take into account that the nearest bus stop is 2 miles from my house, which would take another 7 minutes by car or 40 minutes on foot. Public transportation will get no money from me if I have anything to say about it.

Unknown said...

There's a volunteer group starting big data type work in signal timing from a traffic accident perspective. Might be some crossover:

David Watkins said...

Sounder North is a mostly useless line, with terrible ridership and very little walkshed at the stations. It only still exists for political reasons; the per rider subsidy is embarrassingly awful. (ridership is around 1200 per day, or around 150 per train. Virtually all STEX bus lines have many times this ridership. The riders coming from Everett will presumably just take a 510 or 511, which usually aren't notably slower than Sounder anyway, and orders of magnitude cheaper). Putting any discretionary resources into "fixing" it, rather than investing in actually useful transit, is not a good idea. This even more true now that light rail is coming (eventually) to Everett, which means the utility of Sounder North will be limited to the low-ridership, low-walkshed downtowns of Edmonds and Mukilteo. Sound Transit is wise to invest in more service and expansions of Sounder South while not throwing good money after bad with Sounder North.

As for more parking at the train stations, that's only a step you want to advocate if you want to make congestion (and emissions) worse:

They're sometimes politically necessary to get sufficient political support to build transit, but they make things worse, not better.

I'm open to the idea that a spur to the airport is worth considering, but without any evidence I can't fathom why you expect it to be cheap. Given ST's funding structure, it would have to come out of North King's ST tax revenue. So which do we delay, shorten, or potentially cancel, Ballard or West Seattle? I can't see this as a project worth threatening either of those lines--airport travel is for most people a few times a year; West Seattle and Ballard will be crucial to many thousands of daily commuters.

Mark Anderson said...

Self driving cars may eliminate the need/desire to own. Just touch the app when you need a ride. No insurance, no parking, no hassles

David Watkins said...

John K:

My favorite is the airport rail station.. that isn't quite at the airport! You're left with several blocks walking, staircases, and a pleasant stroll through the parking garage. If done correctly, when the train doors open you should be looking at the check-in counters. What the hell happened down there!?

Blame the Port of Seattle for this one. They fought for the current routing, the City of Sea-Tac fought for a proper airport stop, and Sound Transit

After 9/11, the Port started justifying their preference with bogus security concerns, but they were all in for the International Blvd location as early as 1999. My theory is the Port was run by a car-centric transit-skeptics and didn't really want rail at all. The terrible signage (somewhat improved recently) has bolstered that suspicion.

Linda Newland said...

People in cars seem to think that cars have a right to cross waterways above and beyond the rights of boats. Actually the reverse is true. Boats have the right to unimpeded Federal waterways. Bridges are for the convenience of cars, not mandatory that cars have rights over boat traffic. Causing boats to be held up waiting for bridges to open several times of the day is can't park and wait like a car. Even under power, they are at the mercy of close encounters and changing weather conditions like wind and waves that put them at risk. To add to this mix, large commercial craft would be jeopardizing the safety of smaller recreational vessels in a close encounters waiting pattern.

Sherry Culbertson said...

HunterZ, you're correct in that our public transportation is not yet convenient enough. There are cities that have made it work better... and we are an urban area with geographical constraints that already create the density along major corridors to make it work. I'm looking forward to having ST2 and ST3. It was needed decades ago. Better shuttle service from neighborhoods and local park and rides are also a good alternative to bring people to mass transit hubs. e.g. Some towns already use church parking lots during the week when they mostly sit empty, and have shuttle buses running every 10-15 minutes. Granted, it won't always work for everyone, but with literally millions of new drivers expected to be on Seattle roads in the next ten years, there's no feasible solution that excludes mass transit and alternative transportation.

Mark Anderson said...

Self driving cars may eliminate the need/desire to own. Just touch the app when you need a ride. No insurance, no parking, no hassles

John K. said...

Thank you Linda Newland. Most people are of course completely ignorant of all of that.. which is why there is and never be a solution to this problem. Everyone loves to spout off their "opinion", but the truth is they typically don't have a clue what they're talking about.

Skylar Thompson said...


I agree with most of what you've written, except the road diets. Roads that have been put on a diet in Seattle have not had a measurable impact in traffic capacity (see the city's before&after report on Stone Way[1], and Seattle Met's report on Nickerson[2]). The up-shot is that a four-lane road isn't really four lanes for cars - the right lane might have a cyclist or a bus in it, and the left lane might have turning vehicle. By putting in bike lanes and a center turn lane, all road users can make much more predictable and safe movements.


William Tsang said...

Ugh - normally love the insights on this blog, but agree with many of the comments above - there are lots of fallacies being expressed as fact in this particular post. :-(

Jonathan said...

Imagine if a transportation professional told Cliff Mass how to improve his weather forecasting. It would be about as useful as this heap of bad ideas.

Jonathan said...

Left turn lanes interrupted by turning vehicles and right lanes shared with bikes are not really more capacity. How many traffic engineering courses have you taken at UW?

Ian Crozier said...

Really funny to see the comments about how nobody uses light rail because there is no parking, when has risen from 11000 to 70000 in just eight years to these supposedly inaccessible stations.
It's okay if you don't get it, please just don't try and ruin it for everyone else by devoting the most critical land to the least valuable use.

Unknown said...

Everyone already does pay to maintain these roads. You ignore several facts with your argument.
1. A large majority of bicyclists, pedestrians, and transit riders also own vehicles and pay registration fees
2. A portion of transit fees pay for the same road improvements individual vehicle registrations pay for.
3. The wear and tear induced on the roads by either pedestrians or bicycles is miniscule by comparison to the wear and tear induced by 3500+ pound vehicles.

remnant1978 said...

You guys could just move to Bellingham, where we just get semi annoyed at rush hour and the freeway stays average 60mph

George Reynoldson said...

Taking Eastside commuters off the roads would be quite possible if there was better bus service to the main transit hubs in Issaquah and Redmond. Perhaps a shuttle bus along Lake Sammamish parkway (and 212th) would allow many more people to use the bus and avoid driving to Park and Rides in Issaquah, Eastgate or Redmond before taking a bus into Seattle?

Carl Gronquist said...

You don't like street diets, but you aren't presenting data to back up your opinions. Google maps showing post-diet only doesn't mean anything. I use NE 75th and NE 65th, 75th has been dieted, 65th has not. The dedicated left turn lanes and lack of random right lane passing make dieted 75th flow better than 65th.

Westside guy said...

Cliff, please don't take info about the problematic north Sounder line and then implicitly imply that the Sounder system as a whole is under-used and unreliable. I ride the south line regularly. the south line is reliable, and many of the south line trains over at - or over - capacity on a daily basis.

The schedule issues - only during peak times, and only during the week - are not really under Sound Transit's control. BNSF controls when and where the Sounder can run - and Sound Transit pays a significant amount of money to BNSF for the right to use the tracks. They are starting to run non-peak-time trains, and are (this year, I believe) planning to add more.

Arie said...

My take is two-fold. Solve the short terms problems in a data driven manner as Cliff proposes and then decide what we believe technology will deliver for our region. I favor the tech industry stance which is unanimous on the promise of autonomous vehicles, but I see no indication that our regional leaders share this vision or even give it lip service.

JeffB said...

Seattle leadership is maliciously anti automobile. Ironically this will come back to bite. Automobiles, not trains, are the future. Autonomous vehicles and other technologies will be the choice of most because they will be available at almost any price points and will still be human driveable in last mile situations. Most will shun the trains right about the time we finish wasting $100 Billion around the middle on this century. $100 Billion because everyone knows there will be massive cost overruns with ST3. And Cliff, you forgot to mention the huge failure of the new 99 tunnel that will hav less lanes than the current Viaduct.

If there is a transportation policy screw up to be made, you can be sure that Seattle's terrible leadership will be second to none in continuing to ruin Seattle.

How long before big economic engines like Amazon start moving out of Seattle in order to get their workers to work in a timely manerr

OhanaSchmana said...

These aren't road or mass transit design problems. These are massive population booms and housing scarcity coupled with an outdated adherence to 1950s work schedules that don't require a commute in the first place. Why are swaths of public land devoted to two to three hours of morning and evening commutes in the first place? Our so called traffic problem is actually a civic failure of work design not transportation systems or lack thereof.

Angela B., Kirkland said...

I remember when they built the light rail and were insistent that they had *deliberately* not included any parking lots, because the whole point was to make people bike or bus to the light rail stations. Which of course didn't happen, because it was never going to happen, and if they'd polled a thousand random people in the area, they'd have known that. :/

Kenna Wickman said...

One comment here implies that pedestrians and bicyclists have no rights to the road since they do not pay car tab fees. Yet they breathe the same polluted air polluted by cars, and everyone suffers or will suffer from the effects of Global Warming caused in part by the Automobile. The amount of public land devoted to the Auto is staggering. Everyone pays in one way or another regardless of their mode of transportation.

Cliff Mass said...

Carl G,
It just so happens I was driving on NE 75th St. yesterday,....there was a major slow down where two lanes collapsed into one, and then everyone drove well below the speed limit as one car was driving around 20 mph. Classic example of the problems with road dieting..cliff

PS: MANY 4-lane roads have extra turning lanes near there is NO left turn issue there.....

Thatcher Kelley said...

And what for those who need to go to tukwila three times per week? The toll becomes a burden for them

Michael Goss said...


You're repeatedly using anecdotal evidence to support your point. Others have pointed you to numerous studies showing that "road dieting" is not the boogeyman you are making it out to be. Your responses (and your original post) rely 100% on your intuition and anecdotes. There are people who research traffic, traffic flow, and traffic management for a living. Their studies, as with any science, are based on evidence and peer review. To discount them based on intuition and anecdotes is to make the same mistake that people often make about meteorology.

I absolutely agree with some of your points (especially improvements to light rail, and timed traffic lights), but, based on the evidence, I think your point about "road dieting" is misguided.

Unknown said...

Road diets are not the problem. Why should local residents have to accomodate people who want to use their local streets as expressway alternatives?!? Ultimately you need public transit in a densely populated area. Cars are great in the country but they don't work in urban areas. Why should the people of Seattle be forced to live with the type of roads that make suburban towns so unwalkable?

WeatherOwl said...


Ray Krueger said...

The Olli, by Local Motors, is a self-driving minibus beginning tests on Miami streets before service at the UNLV campus by the end of 2017. This can be deployed in our neighborhoods to sweep riders to bus stops. Riders could be dynamically scheduled as they request a ride from their smartphone.
The minibus is built within a two day period with the body "printed." Guidance is aided by IBM's Watson AI. At 12mph it will likely not be the long-term solution in Seattle neighborhoods.

Blornabie Fakename said...

I'm really surprised (and disappointed) to see Cliff's "solutions" based off of anecdotal evidence instead of data. Really striking to see that from an atmospheric scientist who is constantly fighting the "Well it was durn cold this winter, these weather people don't know what they're talking about" anecdotal evidence crowd.

Cliff, I'm sure you don't lack for connections to educated solutions at UW. And as to your last PS: "PS: MANY 4-lane roads have extra turning lanes near there is NO left turn issue there.....", Many 4-lane roads have extra turning lanes near *MAJOR* intersections. Unfortunately MANY cars turn onto minor side streets from the arterial. Yes, there is a massive problem with it. 145th from Lake City Way to I-5 has two? dedicated turn lanes where it crosses arterials. The remaining 30-40 streets, left-turners are stuck blocking traffic.

Unknown said...

WSDOT needs to live up to their obligation to keep HOV traffic moving at speed. That means both enforcing the laws and considering increasing the occupancy requirements. When buses and vanpools - basically the folks trying to do the right thing - can't get a leg up on traffic, something is wrong.

jjberg83 said...

Why would parking matter for inner-city light rail stations? If anything, light rail stations should be surrounded by narrow 30+ story residential towers and lively, activated streets like every other normal city in the world does. Rapid transit stations in our densest cities need anything but expensive parking garages.

Danimal said...

Jayemarr, you know this isn't how public funding works. I have no love for war, yet I help fund the department of defense. I have no children, yet I happily fund our public schools. C'mon.

Zach Brown said...

I loved this April Fool's day trolling post, your extra dry humor is almost too subtle to detect. Well done, Cliff!

Jim Labbe said...

In Portland I think we've found that maintaining or expanding road capacity in many cases merely transfers congestion in time and/or space and puts off an inevitable and needed shift to a more sustainable, livable, and diverse transportation mode-mix of cars, bikes, pedestrians, cars and transit. WIth smart mixed-use planning, this can encourage people to choose work-living proximity over long commutes. The missing piece is affordable housing which is really key to allowing people to make the decision to live in proximity to where they work.

Skylar Thompson said...

I also don't see the point of building parking at our city's rail stations. Not only is it space better used for housing people, not luxury appliances like cars, but every parking space is just asking for more road capacity to fill it. Get rid of parking, and we'll improve a lot of our other problems, including traffic and affordable housing.

Cliff Mass said...

Skylar...let me explain. Most folks in our city don't live by a rail station or even a bus stop. They need to either walk or drive to such locations. So if you are deep in say, the Laurelhurst neighborhood of Seattle, you could either walk to a major road, take a bus to the U district, walk to the rail station to go downtown. Or you could drive to parking area near the U light rail station and jump on. What do you think most people will do? You know the answer..cliff

clive boulton said...

Sounder Train North has such restrictive hours 4 morning and evening trains every 30 mins. 5:45 am till 7:15 am. Evening 4:05 pm till 5:35 pm. What about all the folks who work outside government hours?

The 510/511/512 buses are often so full till 9 am, till 8 pm. Worst the Sounder trains sit parked at Everett with the huge engines ticking over for hours going nowhere.

Don said...

Why couldn't uw work with car sharing companies (car 2 go or reach, for example) to have a number of car sharing spaces at the U W stadium lot near the uw station. Local rail rIders would park in these spots and proceed to vIa the rail. But instead of the cars sitting all day occupying space, other riders arriving at the uw station would take the cars and proceed to local destinations. One space would serve many users in a day. Use of the light rail would increase, serving many who are not well served by the current bus network. Might reduce some need to drive to rail served areas. Only a few spots would do the work of many, saving pavement and maximizing our huge investment in this rail system.

Cliff Mass said...

Don...this is a wonderful creative idea.....thanks for suggesting it...cliff

Phillip Smith said...

Due to both rapid growth and collective procrastination, Seattle's infrastructure has lapsed into dysfunction. Now we're casting about randomly for remedies. Cliff's suggestions include: park-and-ride lots, restricted boat traffic, new commuter boat lines, removing bike lanes, adding bike paths, punishing distracted drivers, and building a new express route between downtown and SeaTac.

But in the long term, we already know we need dense urban development and frequent mass transit. Self-driving cars may free up lots of space currently used for parking, but they still won't be nearly as efficient during commutes as mass transit. Bikes are pretty unrealistic for most people's commutes, which will continue to generate the worst traffic.

With that goal in mind, and limited resources, why should we invest in a brand-new ferry fleet or airport spur? Why should we subsidize free park-and-ride lots that will someday be torn down for development anyway? (If there is an economical way to provide parking, let the private sector do it.) Why should we continue to prioritize single-occupant vehicles in road planning rather than buses?

We've already committed to some infrastructure to encourage smarter development. Our strategy now should be to support and expand that infrastructure so that mass transit works for more and more of the population. Let's not get distracted by shortsighted fixes (ahem, streetcars) that will only prolong the current mess.

Neel Blair said...

Cliff - I love your weather reporting and your commentary on multiple topics. But your information is simply wrong and bad at multiple places in this post:

1. Your use of Google data is poor compared to the controlled traffic studies that SDOT conducted around road diets. NE 75th, Stone Way, and other sites have specific, measured studies on throughput (# of cars per time period), peak speeds, Top quartile average speed, bottom quartile average speed, etc. Your google analysis is poor in comparison. Road diets actually perform quite well. What they do is make drivers FEEL like they are going slower. But the system as a whole is more efficient in most road diet implementations.

2. Your assertion that there is no drop off at UW Stadium Station is simply false. You'd have to drive around back to see it, but there is a huge pullout that is heavily used by Uber, Lyft, etc. plus family and friends dropping people off. I myself have been picked up and dropped off there multiple times, on weekends, weekdays, etc.

3. Induced demand is real. It has been studied and measured multiple places. I suggest you look into the research and recognize the amount of discipline specific study that has gone into such things. They don't have the number of collectors that weather networks do, but they have quite a bit of data and it all shows that induced demand is real.

4. More cars moving more "efficiently" means more death, injury and property damage. Carnage and property damage follow cars around and they have for decades. Insurance companies are sitting on MOUNTAINS of data that prove that any given intersection , street, etc. with more cars will have more death, injury and property damage than those with lower volumes. Because of course they will. There is no solution for high volume traffic that makes other modes safer and more efficient - more cars always means more carnage and destruction for any given place in the city. And single occupant cars consume road resources at a massively disproportionate rate to everything else on the road.

5. Completely agree on lacking bicycle and pedestrian facilities. WE have many places in this city that are unsafe. Frankly, the more cars there are in a place, the less people will feel safe walking or biking there, and they won't even demand the facilities. That leaves the tiny minority without a choice to use another mode to deal with the unsafe infrastructure. More cars make it worse. Always. Design can only do so much, signage only so much.

Tim Burris said...

@Unknown: entirely agreed with your first two points and mostly with the second. However, I read a study several years ago that showed passenger automobiles also have a negligible effect on road wear & tear. Vehicle-based damage to road comes entirely from heavier vehicles like freight trucks and buses.

Eric said...

"Most folks in our city don't live by a rail station or even a bus stop."

You *are* referring to Seattle, right?

dan said...

Cliff, surely you have heard of induced demand? It's the observed and demonstrated fact that no amount of road widening is ever enough to eliminate congestion. On the contrary it just creates more traffic after an initial period of relatively freer flow.

Unknown said...

I read that bottled water is what needs to be taxed for road funding. It is heavy as hell when transported in trucks and in most places unnecessary.

Cliff Mass said...

Neel Blair
I don't think you are correct. If one looks at careful statistical studies, one finds marginal or no benefits for road diets and they do harm on busy streets. I will do another blog about this, but please check the will see the issues...cliff

Cliff Mass said...

Dan... by your logic, one should make all roads one lane. That is not reality. Reducing the capacity of our roadways when the region is blooming and light rail will take decades to install is not a rational choice....cliff

Skylar Thompson said...

Cliff, one of the things I appreciate in your meteorological reporting is your citations and raw data. Can you provide something similar for your assertions concerning the negative impacts of road diets, and the need for parking around urban light rail stations? I would be interested in seeing quantitative data backing it up.

Cliff Mass said...

There are a large number of studies that show that road dieting is often ineffective or worse, many by the US government and Civil Engineering Depts. Here is one:
Look at the graphics.

Or this one from Michigan State:

I have been amazed how lacking the evidence is for road diets, with many studies being very, very poor.....I will blog about this in the future..cliff

Mike Francisco said...

We are already on a "road diet," due to the amount of space taken by parked cars.

The speed limit on most city streets has been reduced to 25 mph, which theoretically reduces throughput. In practice speed limits are poorly enforced. People tend to drive faster on wider roads, making them less safe for pedestrians, cyclists, and themselves. I don't see why I should put up with less safety as a cyclist or pedestrian for the sake of people who insist on driving cars into the city center. If road diets are reversed and pavement is improved then there had better be stepped up enforcement of speed limits and distracted driving. My guess is that there will be none of the above, due to constrained budgets and local politics.

marty said...


The Nhta study you cite was from 2004, and itself notes that the crash reduction results are statistically not significant. And the study suffers due to the lack of sites.

The Michigan state study doesn't appear to have a significant number of urban sites that would be an apples to apples comparison with seattle. But it does state that roads with significant left turns and high volume benefit most from RD, which is what we see here in Seattle.

Why cherry pick studies from 2004 to support your argument on 2017?

Cliff Mass said...

marty...not cherry picking...and I could provide another 10 studies. The Michigan study did include urban sites. The fact the results are not statistically significant IS THE WHOLE POINT. There is no real evidence for the road diets. Almost none of them evaluate the increased congestion they cause...just total road throughput. The more I read, the more it is evident that careful studies show little value and that favorable studies are often poorly done. I plan a comprehensive blog on this topic..cliff

Mike Francisco said...

Road diets don't work the same everywhere, as the studies you noted point to and results vary widely.

But take Nickerson or Mercer as local examples. I've observed that the throughput of cars has more to do with the backup on I-5, multiple intersections at SLU, and the special light cycles for streetcars (Mercer), or with bridge openings (Nickerson) than with the added bike lanes or left turn lane. I've seen an SDOT study for Nickerson showing that collisions have dropped 23% since the street was redesigned.

I use the Mercer bicycle underpass at Aurora several times a week, riding my bike to shop at the QFC on Lower Queen Anne or for recreational purposes getting to and from points west. From my point of view as a cyclist, it is a huge improvement over the narrow sidewalk that wasn't even wide enough for pedestrian traffic. or trying to maneuver my bicycle around cars backed up for several blocks there every afternoon. Most of those backed up cars are trying to get to I-5 at rush hour- which is itself a miles-long parade of vehicles. I find it very unconvincing that the city should remove the bike underpass in order to improve flow. This would effectively just be a wider Mercer street parking lot for most of the afternoon.

My point is that there is more to managing streets than throughput of motor vehicles. More even than safety. Roads should be built based on engineering design and analysis, not just a blanket move towards or away from road diets. They are public property and used for a wide variety of purposes other than moving cars - as you well know.

Benjamin said...

As a loyal reader of both your blog and the one linked above, I implore you to give transportation planning the same critical look that you give meteorology. Please also do more research into "induced demand" as well as the capacity of the entire system as a network, and not just single corridors.

James Sledd said...

Cliff, try the road conditions and lack of bike infrastructure in Boston. Seattle is a Mecca by comparison. Potholes can swallow a Volvo, bike infrastructure is non-existent, and drivers exhibit a disturbing combination of aggression and laziness. The street layout is nonsensical at best. I can't wait to move back West

marty said...

From reading the linked studies it didn't refute more recent findings from our own backyard, that the road diets reduce injuries at little cost to drive times. (Surely its linked above by now)

This is a prettty good analysis of many studies:

Lack of significance goes both ways and isn't a proper argument against evidence ( road diet reduces injuries).

Whats the difference between congestion and throughput? If the same number of cars travel the same distance in the same time period (aka throughput) not sure what "congestion" increases.

Well looks like there are a number of people waiting for the comprehensive explainer.

Ondrej said...

For those of you interested in bridge openings, here is an analysis and data visualization of 5 years of Ballard Bridge opening data:


dan said...

I'm simply mentioning the concept of induced demand, something that's been extensively studied by traffic engineers. Traffic (vehicle numbers, etc.) always reaches a congestion point, and adding more capacity just chucks the problem down the road (so to speak) a small distance before peak hour congestion occurs again. Adding lanes is the solution that is never ultimately a solution. Particularly in an ever growing city like Seattle. Getting rid of the road diets, first of all probably would do little to alleviate congestion even on the short run, for varoous reasons including the loss of the middle turn lane; and in the long run (possibly measures in months) peak time congestion would be back where it was. There have to be (and are) other solutions.

Cliff Mass said...

dan and others.... I certainly know about induced demand....but that is not the issue. You have a certain demand right now...including absolutely essential transportation needs....and the city has REDUCED CAPACITY. That is not a rational approach for roads that have a lot of traffic during rush hours. Road diets are not appropriate for busy roads (FHWA documents state this explicitly). Keep current capacity and build more transportation options (rail, buses, and I believe marine)...cliff

HunterZ said...

All it takes for a road diet to become abject failure is for one bus to stop to load/unload passengers during rush hour. It's bad enough on a two-lane road, where all the slow drivers move into the left lane and go slower than the bus, because they're afraid of getting stuck behind it when it stops.

Skylar Thompson said...


SDOT's studies of road diet impacts on motor vehicle throughput find little, if any, effect, particularly after accounting for the increased capacity from not being closed due to traffic incidents. I don't think anyone is arguing that road diets are counterproductive (at least for drivers) for *very* busy roads, but even that Michigan study you cited said that delay is only likely over 1,000 vehicles/hour. SDOT doesn't consider 4-to-3 diets over 25,000 vehicles/day, which is saying about the same thing. Sand Point Way (the road way you seem most concerned about) drops quickly east of University Village to 16,000 - 20,000 vehicles/day.[1]

UW's own Andrew Desmond modeled the costs and benefits of the Rainier road diet, and calculated that the benefits (mostly in reduced injuries and deaths) vastly outweighed the costs (travel delays):

The reduction is injuries comes from both a narrower roadway to cross (less opportunity for a crash), and a substantially-reduced rate of speeding. The Stone Way diet, for instance, reduced 10+ mph speeding by 75%. The speed limit along Stone Way is 30mph - a pedestrian hit by a vehicle traveling 40mph has a 75% chance of severe injury and a 50% chance of dying, compared with 50% and 25%, respectively, at 33mph[2]. Given that we're all pedestrians at some point, those numbers should give pause to the desire to keep cars moving as quickly as possible.


Arie said...

My implicit bias in favor of road diets. After all they reduce accidents, effectively meter traffic headed towards choke points, and are counter-intuitive (and the dolts in the suburbs will never get this).

However in the work I do, I'd have to look at overall throughput at all workloads and consider things like wasted energy consumption and non-peak performance. I've never seen a traffic study that comes close to the types of systems analysis that teams of hundreds of computer engineers and architects can produce. That's not a jab at traffic engineering, it's just the reality of having limited resources to solve billion dollar problems free of what the local political climate may be.

Of course if this was a compute problem, we could assign values to higher priority traffic and let those guys through (I'm thinking ambulances, Cliff and me :)) and park the rest temporarily.

MJ said...

SDoT talks about transportation choices, yet people cannot park near a Light Rail station. During the daytime thee is under utilized parking near many light rail station in South Seattle, see data in the following link 2012 report

The City needs to open up some of the parking, say one half of a street, for oth City resident to be able to use the Light Rail


MJ said...

SDoT claims to support transportation choices, yet you aren't allowed to park near the Light Rail stations in South Seattle. The parking utilization at these stations is very low during the day, see Seattle data

The City needs to open up some parking, say one half of a street to allow other city residents to use the Light Rail. This adds to the Transportation options of residents and needs to happen. Residential parking peaks late night/early am and commuter parking is a daytime event. Thus an opportunity to better utilize public street space exists.

Jeremy said...

Cliff failed to mention the number one reason(s) that traffic has reached this point: We live in a city. A city is a large, densely settled region by definition, and thrives on its volumetric efficiency. Single passenger vehicles are ridiculously space inefficient, and are therefore a poor transit solution for densely populated areas. Seattle is finally facing the music after near economic collapse.

Seattle suffered a protracted population decline between 1960 and around 1985, but road building, including the construction of I-5 and the Viaduct continued during that period. Meanwhile, numerous areas around downtown became large parking lots as industry diminished its footprint, and older buildings failed. It was as if someone built a home for 20 people, and by the time it was complete, only 10 chose to move in. So much few people. This hid the source of Cliff's problem directly under his nose: again, single passenger vehicles are relatively enormous given their intended purpose. They are a lazy and ineffective solution to the problem of transit.

The average vehicle is nearly 16 feet long and 6 feet wide. You can't run them elbow to elbow and bumper to bumper, of course, so each one requires a 10 foot width, and about 36 feet of front to rear space to travel safely at low high speeds, each *theoretically* should require a 12 foot lane width, and 116+ feet of front to rear space. We drive like idiots, so I'd say we might occupy more like 36-60 feet no matter the condition. Therefore, a single human in a car requires anywhere between 360 square feet, and 1392 square feet. A single, first class airline seat on a short haul flight, like one of Alaska Airline's 737s is roughly 21 inches wide x 39 inches deep. So...the average person can be comfortably seated in space that's less than 6 square feet, but the average single passenger vehicle is 96 square feet, and requires anywhere from 250 to 1300 additional SF to operate. One human, who easily fits into a 6 square foot box seated, requires a space 60 to 230 times that space to travel. Oh...and you have to provide space for that person to park the silly thing...while they're not using it...and cars spend far more time parked than they do moving.

That's the problem Cliff. People are little, cars are big. Cities are dense. Big things fit very poorly into little spaces. If cities are thriving, they're attracting inhabitants. There isn't anything that can be done to create a network of streets anywhere that will solve the basic volumetric inefficiency of a single passenger vehicle. This is why we've turned to road diets and alternative forms of transit. SPVs ultimately would have choked themselves to death in the not-too distant future on their own, and left us with less space for humans, and a far lower ceiling capacity for transit. Some ideas are too poor to be saved. Single passenger locomotion in an urban area is one of those bad ideas...probably among the worst.

HunterZ said...

@Jeremy - you lost me at you assertion that the average person can be comfortably seated on a 737 ;)

Jeremy said...

@hunterz - note that I used first class dimensions :).