When WSDOT ferries make the news, the press seems to focus on fiscal issues, rather than the logistical aspects of the ferry system. We wanted to remedy that and answer the question – are ferries generally on time?

We filed a Public Records Request with WSDOT and here we present findings for on-time rates for calendar year 2014, with a focus on the difference between actual and scheduled departure times. For simplicity this analysis only considers Puget Sound region ferry routes (i.e. non-San Juan Islands routes). Also, because WSDOT runs a holiday schedule on most Federal holidays, we specifically accounted for those dates.

Overall we find WSDOT Puget Sound region ferries to be very reliable. Over approximately 133,000 sailings throughout 2014, the average departure occurred 2.8 minutes after the scheduled departure.

Figure 1. Click to Enlarge.
Figure 1. Click to Enlarge.

In Figure 1, we used linear regression to add a trend line to visually show trends in departure time delay for all routes and then stratified those values by route of interest. As a whole, the data shows minimal variation in departure time with a modest bump in departure delay towards the end of summer. One aspect to note is that there are days that ferries left early enough ahead of schedule to bring the daily mean delay below zero, although it is unclear why this happened.

Figure 2.
Figure 2.

This is a slightly different plot with dot sizes representing delays by day with the dot color representing the type of day. Again we see the same patterns of delay as observed in Figure 1 but we can also see that certain routes (e.g. Seattle – Bainbridge Island) tend to have more delays on the weekend sailings while other routes (e.g. Keystone – Port Townsend) tend to have more departure delays during the week.

Figure 3.
Figure 3.

One could arguably say that Seattle – Bainbridge Island and Vashon – Fauntleroy are the two largest commuter ferries so we focused on those individually. WSDOT reports their ferry data on a route-specific level, which can lead to complications with data for the Fauntleroy – Southworth – Vashon route due to the three routes being interconnected. For this analysis these three routes were combined into Figure 3.


Finally, we looked the daily mean crossing time for each route compared to the annual mean crossing time to observe changes in crossing times over the course of the year. Because this figure only looks at crossing times, any variation in trip length is due to factors that occurred while sailing.

In conclusion, we observed that WSDOT ferries are generally very consistent and there is some ability to predict delays in advance (such as a summer weekend afternoon sailing). With the introduction of reservations and better online notification of ferry capacity, WSDOT is attempting to make for a smoother sailing experience while dealing with the rapid population growth that faces many other transit services in the state. Based on our observations, the ferry will almost always leave within 10 minutes of scheduled departure, the only question being whether you’re on it or not.

52 Replies to “WSDOT Ferry Reliability”

  1. Good stuff gents. One thing worth considering is we need to keep recapitalizing the fleet as there are no less than three Evergreen-class ferries from the 1950s and four Super-class ferries from the late 1960s that have ginormous load & speed capability that need replacement. We run our ferries hard with no real spare capacity in mothballs….

  2. Right on the mark “AvgeekJoe.”
    We’ll need at lest one more Kwa-di-tabil class and 5 or 6 more Olympics and a couple of Jumbos to get us into the 2030s. But the DOT and our “culture” must also prepare for higher personal vehicle fares and lower walk-on fares to begin the transition from a “by auto everywhere” culture. The next generation of 16-20 vessels, in service from the mid-2020s and beyond should have lower auto capacity and greater walk-on capacity and yet be able to continue delivering close to on-time service despite fog and winter weather.

    1. Lower auto capacity? Uh, no. Social engineering like you propose is never going to be supported by the legislature.

      I rarely see the passenger capacity of the current Mukilteo-Clinton ferries used anywhere near capacity. Cars, not so much – and that is with Island Transit.

      I agree we need 5 or 6 more Olympics – as long as they can handle Rich Passage. If we can swing one more Kwa-di-tabil, great. This way we can put into Eagle Harbor the Supers & an Evergreen as some reserve capacity for the inevitable ferry emergency when a ferry is out of service for a long time. Or if a major floating bridge or the Deception Pass Bridge is taken out…

      1. Politicians may run out tired, disingenuous lines about “social engineering”, but there’s no reason to stoop to it here.

      2. Lower auto capacity? Uh, no. Social engineering like you propose is never going to be supported by the legislature.

        No choice about transportation infrastructure isn’t “social engineering” by this standard. How on earth is a plan to slightly reduce a massive subsidy for private car use any less ‘social engineering’ than a plan to continue such a subsidy in perpetuity or expand it? It can only come from the pervasive, toxic ideology that’s cooking the planet, that individual private car use is somehow natural and other forms of transportation are deviations from that norm. Please don’t stoop to this kind of nonsense. You’re capable of making serious arguments in good faith without this kind of nonsense; I’ve seen you do it.

      3. And the current dependency on petroleum, asphalt/concrete/auto dealerships and repair shops/parking lots, etc for nearly all of the last 100 years is NOT “social engineering”? Please re-read your 20th C US history, Joe.

      4. I just think dismissively that kind of, er, stuff is going nowhere with this legislature or this culture. Even Seattle people love their cars.

        No what we need to do is market transit as way better than that 2nd car or 3rd car. Oh and even more…

        I don’t own a car, I’m just trying to get you folks to realize reality. Just like you do to me :-).

      5. According to the American Heritage® Dictionary of the English Language, Fifth Edition, social engineering is ” The practical application of sociological principles to particular social problems.”

        In this case, encouraging more walk on traffic would be the sociological principle, and anticipated growth of auto traffic would be the social problem. If you accept these labels, then It is in fact social engineering by the true definition.

        The real question we should be asking is should we pay for more ferry’s to shuttle ever increasing number of auto traffic, or should we simply build a bridge?

      6. I sure would like to see a serious debate about more bridges….

      7. There’s always the New York method.

        After 9-11 vehicles were banned from traveling on the Staten Island ferries. The auto decks were enclosed and turned into more passenger space. You wanna drive? Then pay for da damn bridge! You want personal transportation? Buy your own boat.

        Now THAT is discouraging auto use.

        That said, it says a lot about the awfulness of American transit in general that people would rather spend hours in the ferry line that take transit.

      8. I’m just trying to get you folks to realize reality.

        You should really be clearer. Everyone understands that ‘social engineering’ is generally employed as a pejorative for describing overly intrusive, undemocratic public policy interventions into peoples’ lives. “We shouldn’t do that because that would social engineering” tells us something about our politics, whereas “We shouldn’t attempt to do that because it would be unpopular and unlikely to succeed as a political matter” is an entirely different claim.

      9. “It can only come from the pervasive, toxic ideology that’s cooking the planet, that individual private car use is somehow natural and other forms of transportation are deviations from that norm.”

        I think djw is spot on in associating the term social engineering to statements like the quote above from djw.

        However, we need to separate the idea that the American sense of individualism and the love for our cars will always be tightly coupled with carbon emissions from the past and present carbon emission levels of our beloved cars and the sense of individualism they project. It would be truly cynical (and short sighted) to think that the future of automobiles will rely on fossil fuels as a means of energy to power them. This includes acknowledging that even modern (and foreseeable future) electric cars indirectly emit carbon via the power plants that send power to the charging stations. It is true that overall carbon emission trend from cars is bending down due to the better fuel mixtures, MPG standards, and hybrid/electric cars, even while the number of cars using the transportation infrastructure increases every year.

        So what? Well, Americans should consider that this when we make decisions about transportation infrastructure. Why not embrace the American sense of individualism and our love of cars, and plan that develop our transportation infrastructure in anticipation that there will be an continued increase in car ownership/usage? Willfully constraining our transportation infrastructure to motivate more usage of mass transportation for the purpose of limiting carbon emissions is short sighted, hurts our economy, and is an unneeded wedge issue that only divides us as Americans.

        As a huge supporter of mass transportation, (I love walking on the ferry for my daily commute, and walking 1.5 miles to my office everyday.) I think we should continue to expand mass transit to meet the needs of those who would use it as a matter of choice and preference for ones unique circumstances.

    2. The Kwa-da-Tabil ferries (often referred to as KdT or tubtoys by ferry fans) are not really suitable for any other runs besides than Point Defiance/Tahlequah and Port Townsend Coupeville and serve no purpose in the system other than an emergency backup. This was seen with the steel electrics, for the last 10 years one out of the four was always in mothballs except for the final emergency period. Lesser known is that the Kdt’s are improperly engined and eat far more fuel than they should.

      Besides replacing the Super class ferries (in particular Hyak which did not have a mid-life update) WSF long term needs a ferry in the 100 or so car capacity without gallery decks to use on the “inter-island” run in the San Juans to serve as a backup to Sealth who will take this capacity on long term after the last Evergreen is retired. It is vital there to have a large flat car deck permitting the unusual loading patterns necessary there (such as turning cars around). Additionally it can serve as a much more effective backup than a 64 car ferry and can add capacity to Point Defiance when/if it is needed in 20 years or so.

      Also the Jumbo Mark II class ferries were designed to allow the upper decks to be enclosed to give them capacity for as many as 500 more passengers, therefore there isn’t as much of a need for an additional vessel of that size until Spokane and Walla Walla are due for replacement.

      1. Note that in regards to the Steel Electrics, Nisqually was not even an emergency backup. She was fully mothballed and WSF had to put quite a bit of work into her to restore her to service the last year.

    3. The motorcycle fares should be changed tomorrow. Head down to Colman dock today on foot and you’ll pay more than if you brought a motorcycle.

      1. All the commuters to my office from Bainbridge and Kingston commute via motorcycle upon the ferry.

        As for raising the fares for us motorcycles, I disagree. Motorcycles occupy those spaces on the boat that cannot be filled by cars. You see them. Hugging those nooks and gaps that are too small for cars. Remember, four to five motorcycles or scooters can easily fit in one conventional parallel parking spot.

        …and unlike peds, I pay both ways on my trips across the Salish Sea.

      1. Agreed. A decent place to rack a bike – not the string to tie to the railing – would be quite useful.

    4. Actually the legislature has directed WSF to use pricing “to level vehicle peak demand and increase off-peak ridership” because they want to handle growth without expanding the system.
      Currently, passenger fares are generating $12M more than the passengers’ share of the cost of running the system. SOV’s are not covering near what they cost to transport. That’s social engineering, too, but with highly undesirable outcomes.

      1. Ann, I agree we passengers are paying an outrageous fare. Over $5 to get across from Mukilteo to Clinton? $2 will get you a lot more actual distance!

  3. Did you really need a public records request to get the information? WSDOT publishes an on-time summary every quarter in the Gray Notebook. The summary is no as detailed as your report, however.

    1. Hmm, I did not know about the Grey Notebook. Basically I emailed a GIS guy at WSDOT and he referred me to someone else who suggested I fill out a request which was basically a detailed email. They replied with an email with a tracking number and an official letter as a pdf and then I got the data a few days later. Thanks for the tip though!

    2. I salute these guys for using the Public Records Act for its intended purpose.

      1. Yes, it’s good to see that the info arrived quickly. I wonder how much info about AmtrakCascades is available.

    3. WSF considers a ferry to be “on time” if it departs within ten minutes of the scheduled departure. This article digs much deeper, and – in my view – addresses how most people define “on time.” Great work!

    4. If you file a public records request for something that’s already available it’s not that much work for them to give you the data you request. They might also point you to where to find it but they do have to directly provide it.

  4. If I recall correctly WSF’s greybook data takes into account some “lag” to the schedule, as in a boat is “ontime” if it departs within a set # of minutes from the scheduled time. That makes sense when you realize they can throttle up a bit and still arrive on-time.

    This however is more detailed as it shows the actual reliability down to a much lower level.

    1. Also Zach, in response to your question in the blog on ferries leaving earlier than planned, one major reason that can happen is an emergency medical run. Are you seeing this on one or two runs a day or many runs? I imagine if you have a few of those a day and run pretty close to on-time otherwise you might end up negative.

      1. Kyle – thats an interesting thought. Ideally we could cross-reference with EMT data. The early departures were not uniform at all and were way more frequent than we were expecting.

    2. Another problem there is having to compensate for tide currents and the like. If the auto deck is full and nobody is in the waiting room, they probably figure there’s no reason to not leave early, and if the tides are counter they can pad the schedule a bit better if they leave early.

      1. That was going to be my question – if you’ve got the boat loaded to capacity and no one’s nearby still buying pedestrian tickets, it seems like it would be ok to shove off.

  5. I like a slow moving sea voyage as much as anyone, but this is the 21st century. China is building tunnels and bridges that would easily take us across Puget Sound on a regular basis, and provide access to the biddable land we so desperately need for lower cost housing.

    1. But John, the problem of that is more sprawl which means more congestion and more pollution.

    2. They don’t want bridges. Bridges would bring growth and destroy the rural atmosphere.

      There’s plenty of room for low-cost infill housing in south King County without building bridges across the Sound.

      1. Yes, thanks for confirming that all the talk about “Urban Density” is not from a real need but from desire of Land Hogs to keep everything as-is.

    3. I suspect China has done nothing like the kind of structure that would be needed to cross the Sound.

      1. And water depth of the china Hangzhou Bay bridge less than 15m throughout the bay. Water depths on the edmonds kingston route greater than 150m.

      2. We might have to build an artificial island…like they are doing in South China Sea

  6. Zip cars and even driverless are coming far faster than I would have imagined even a year ago (I would have been entirely skeptical). It may not be necessary 10 years from now to have all that large an automobile capacity on ferries.

    1. If it’s ever needed you could in theory retrofit the car decks, especially the upper gallery decks out to be passenger decks if that’s ever needed. See the Staten Island ferries which are a similar design but with multiple passenger decks instead of car decks.

      Also keep in mind with many of the runs the area you are connecting into are exceptionally rural and likely to be lacking any appreciable mass transit systems any time soon, if ever. Whatever is going is likely to be a “car”. Zip cars and driverless cars still take space and having a thousand loaner cars sitting in Friday Harbor for the 6 months of the year they are needed would be very expensive.

    2. Even if another car is ready to go on the other end, driving on board still offers the convenience of not needing to load and unload all your stuff, plus not needing to stand with your stuff for the entire trip.

      (Unattended objects are considered a security risk – except when they are inside of a car, a which case, it’s safe).

      I’ve seen a lot of cars on the ferries that look pretty loaded. And for large delivery trucks, unloading everything at the ferry and loading again on the other side would take hours – it would be a complete non-starter.

      1. I don’t get why stuff standing alone not in a car is a security risk, but stuff in a car isn’t. Have people never heard of car bombs? (which, to be fair, don’t usually detonate in the US)

  7. That will get you some of it but they won’t do it for just EMTs. They will leave early for a multitude of reasons including commercial ambulance transport, woman in labor as well as tides/weather or marine traffic. Which is more common than you’d think considering a baby was born on the Tacoma last year. There is however a lot of the whole “captains prerogative” thing going on.

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