Is Link light rail seeing more service interruptions?

Credit: Sound Transit

Two years ago I wrote a piece about the frequency and duration of Link service interruptions (blockages, accidents, power outages, etc). Given the recent, high-profile service meltdown on June 12, it makes sense to revisit the issue. How often do interruptions occur? How long do they last? Have they become more frequent or longer in duration over the last two years? I parsed several hundred email alerts from Sound Transit to find out!

I measured interruptions starting in December 2015, when I started subscribing to the Sound Transit rider alert emails. From then up to June 28, 2019, I count 144 separate incidents*. That’s roughly one interruption every nine days and is the same rate I estimated in my 2017 piece. Counting the number of interruptions in 30 day intervals confirms that the base rate of these incidents has been quite stable, in a statistical sense.

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How Often Is Link Light Rail Service Interrupted?


Link Light Rail has had some rough patches over the last month with a couple of major incidents occurring during peak commute times. The first was a Link-involved accident on MLK at the tail end of the Sept. 15 afternoon commute. A week later, Link was disrupted by a drive-by shooting in Columbia City that resulted in a crash near the tracks. These incidents are a timely reminder of the vulnerabilities (and dangers) of a rapid transit system that shares right-of-way with vehicle traffic. But how often is Link service disrupted? I’ll dig a bit into the data to shed some light on the statistics of Link interruptions.

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Seattle is Denser Than 90% of Large U.S. Cities

There’s been a good deal of recent attention to Seattle’s continued growth spurt. The Upshot column in the New York Times points out that we’re also one of the few cities that is growing denser as we add population. In fact, Seattle is already cited as the 8th most dense of the 50 most populous U.S. cities. I’ll expand on that last fact in this post – hopefully giving some context for what our current state of density means relative to the other large cities of the U.S.

Two questions arise naturally: What is a “large” city? And how should density be measured? Here, I’ll define a “large city” as one with at least 100,000 residents. Such cities are in the 99th percentile of population for all incorporated places in the U.S. – so that seems sensible. As for density, I find the population-weighted density metric to be more informative and interesting than the usual “population divided-by area” measure. Population-weighted density measures the density at which the average person resides and is less sensitive to the amount of vacant land within city boundaries. For an excellent example of why one might prefer weighted density, see Honolulu, Hawaii. The traditional density is about 6,000 ppl/sq. mi., but the weighted density is closer to 25,000. That difference is like suburban Renton vs. Lower Queen Anne, so it is significant!

How does Seattle stack up when it comes to weighted density? To find out, I pulled census block group level population estimates for all U.S. cities with over 100,000 residents from the 2015 American Community Survey. In all, I calculated weighted densities for about 300 cities. Here’s what the distribution of those densities looks like:

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A Few Ways to Calculate Seattle’s Population Density

How dense is Seattle? It depends on what geographic area is meant by “Seattle” and also temporal factors like day of the week and hour of the day. For instance, the Downtown Seattle Association’s 2014 economic report estimates nearly 60,000 residents in the “greater” downtown area (roughly, Mercer to SODO and Elliott Bay to Broadway) with a weekday population exceeding 230,000. That implies a pretty impressive density. And downtown Seattle isn’t alone. Redmond, per the census, has one of the largest increases in weekday population in the country. It’s interesting to see what effect this daytime concentration has on the distribution of people in the region and on overall measures of density.

Let’s look at downtown Seattle first. Using the Census Bureau’s 2014 LODES data on primary employment locations, I count about 225,000 jobs in greater downtown. The geographic distribution of these jobs by census block group is shown below. GIS files defining census boundaries came from the PSRC’s public data.

The area adjacent to Westlake Park dominates the map with nearly 40,000 jobs in its block group alone. And of course, most of those workers don’t live downtown; they had to come from somewhere else. The LODES data set comes in handy here because it estimates the home locations, as well as the employment locations, for all workers in the state. After the jump, I’ve mapped the percentage of the population that has a job downtown for every census block group in the metro area based on the 2014 LODES data.

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A Day in the Life of Seattle’s Population Density

It is relatively easy to find data and visualizations for residential population density. Here is a map of Seattle census tract densities via the City of Seattle, for example. But everyone who commutes to a job knows (sometimes painfully) that a static view of residential density is just a slice of a larger, dynamic landscape. The geographic distribution of people in the city on an average Thursday afternoon is significantly different than it is at midnight on a Sunday. This is especially true for areas with strong, single primary uses like Paine Field (Boeing Factory), Overlake (Microsoft), and Downtown Seattle.

In an effort to understand these daily shifts in our region’s population density, I built a (very) simple model of the home-to-employer population shift on an average weekday for the Seattle metro area. I used two data sources: American Community Survey population estimates and Longitudinal Employer-Household Dynamics data with origin-destination employment statistics. Both sources are published by the Census Bureau and contain data down to the census block group level. Assuming that most* people with outside-the-home employment leave for work in the morning and return in the late afternoon, I produced the population density animation in the embedded video.


A few areas really stand out in the animation: the downtowns of Seattle and Bellevue, UW, the Microsoft headquarters in Overlake, and the Boeing Factory in Everett. If you know your Puget Sound geography, you can also spot the Boeing Factory in Renton, Factoria office parks, SeaTac Airport, and the warehouse district in Kent. There are also subtle decreases in density for heavily residential areas in suburban districts. Of course, these observations are not qualitatively surprising to anyone who knows the Seattle area. More interesting are the estimated population densities in these areas. Parts of downtown Seattle seem to achieve 5200,000+ ppl/sq-mile during some weekday afternoons – literally off of my scale! Good luck serving that kind of density with single occupant vehicles.

I should probably mention some obvious shortcoming of this model. It is built on a simple set of assumptions and cannot account for non-standard commutes, like night-shifts, and non-commute trips which are a certainly a significant portion of trips made**. The model also doesn’t know about the paths that people take between home and work. Still, it is quite striking to see how the region’s population concentrates into half-a-dozen CBDs during the course of a weekday. And I have a renewed appreciation for the economic importance of downtown Seattle to the region.

[*] I assumed that 80% of people with employment outside the home will need to commute on a given weekday. This is not a scientific estimate; it is a guess and nothing more.

[**] Non-commute trips are likely more spread throughout day and night, however, which would dilute their aggregate contribution to shifting population density

Transit Report for Osaka, Japan

I recently had the opportunity to sightsee around Japan for a week. As somewhat of a transit tourist, I’ve experienced several of the busy, urban rail systems of the western world, but the scale of Japanese intercity and urban transit still shocked me. For some idea of the orders of magnitude involved here, consider that Shinjuku Station in Tokyo – a single train station – serves around 3.6 million riders on an average weekday. That is about 2/3 of the weekday ridership for the entire New York City Subway with over 400 stations. The urban Japanese would probably describe our three car Link trains with the word “kawaii” – how cute.

Japanese rail, or even the regional network of Tokyo, could easily occupy a dozen of these transit reports. So, I’ll narrow my focus to a city and transit system of (slightly) more manageable complexity: Osaka.

Osaka from the castle hill

Osaka city has an official population of 2.6 million, but it is situated as the principal city in a metropolitan region (known as the Keihanshin) with almost 20 million people. The city’s economic importance within Japan is only rivaled by Tokyo. Accordingly, Osaka has a world class transit system consisting of public subway, privately operated regional and long distance rail lines, and a bus network. In the spirit of STB’s excellent Transit Report Card series, I’ll try to cover some aspects of the transit network like scope, fare structure, and accessibility, among others.

Lines ridden

  • Midosuji and Nagahori Tsurumi-ryokuchi (Osaka Municipal Subway)
  • Osaka Loop and JR Kyoto (Japan Railways West)
  • Keihan Main (Keihan Electric Railway)

Design and Scope

In my experience, you really can get just about anywhere you want to go on Osaka’s transit network. The municipal subway, in particular, is extremely useful for getting around the core of the city.

Looking at the subway map, there are a couple of design elements to note: a roughly radial network at the outskirts and a well defined, rectangular grid of lines in the central area. Jarrett Walker-ites will note that if one were designing a transit network for maximal ridership in a multi-nodal city like Osaka, it would probably look about like this. Indeed, the subway is heavily used with nearly 2.5 million weekday riders. For comparison sake, that’s well more than double the DC Metro ridership on 70% of the track length. Of course, Japanese land use patterns are inextricably linked to the high utility of their transit systems…but I digress. For me, the pedestrian tourist, this network meant total freedom of movement – I was never more than a 10 minute walk from a subway station.

For longer trips within and outside the city, there is a network of regional routes operated by a handful of private, for-profit companies. The largest and most important of these is the West Japan Railway Company, or JR-West. Their routes are seen on the subway map as narrow, blue lines with a JR prefix on the route name. JR’s Osaka Loop Line, as its name implies, runs in an elongated circle around the core of Osaka, connecting with nearly all of the subway lines and several other regional lines. Having lived in Houston for a while, the Osaka Loop and Tokyo’s Yamanote line struck me as the transit analogues to the giant freeway belts of I-610 and Highway 8. For intercity travel, JR and others operate numerous lines to neighboring Kobe, Kyoto, and Nara metro areas.

Fare Structure

Subway fares range between 180 and 370 yen and are tiered based on distance traveled – which is actually quite comparable to the fare structure and cost of Link. The regional train lines generally charge a base fare that varies with distance traveled; express or special services add an amount in addition to the base. Costs range from a few hundred yen within the city to thousands of yen for long distance express services. (At present exchange rates, $1 US is about 110 yen).

Single ride tickets for subway and regional lines can be purchased from machines and, usually, staffed ticket offices in all stations. Additionally, the ICOCA stored value card can be used on just about all of the routes (subway, regional, bus) in Osaka. As far as I know, there is not a sizable financial benefit to using an ICOCA, but it is certainly faster and more convenient. You can even use it at some vending machines and convenience stores! It’s worth noting that the contactless reader technology in the Osaka area is also compatible with many other cards, like SUICA from the Tokyo region.


Rail transit is the fastest game in town in urbanized Japan – no question. According to Google, the drive time between Kyoto and Osaka is at least 45 minutes (i.e. without traffic) and a flat 28 minutes on the JR Kyoto line.

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For longer distances, one can ride a shinkansen bullet train which hits top speeds of 150+ mph. Mic. Drop.

Frequency and Reliability

The Osaka subway seems to run at usual metro-like headways of 3-5 minutes all day. I certainly never felt like I had to wait. The service span of 5am – midnight does leave a bit to be desired given the very active nightlife of Osaka.

In comparison to many US commuter rail systems, the JR lines often run at astoundingly high frequency. For instance, the JR Kyoto local line runs every 5-10 minutes off-peak! Express and Special Rapid services tend to run closer to half-hourly off-peak frequency. The on-time performance on the regional routes is also very high. Japanese trains, in general, seem to run obsessively on schedule.


Major train stations in Osaka and many other big Japanese cities tend to be crowded, labyrinth complexes where transit and commerce meet head-on. An extreme example of this is Namba Station which is seamlessly integrated into an underground shopping mall (or is it the other way around?) called The Namba Walk.

The Namba Walk

This can make navigation a challenge during transfers, especially when a decent portion of the wayfinding signage is in a language that you can’t read. However, it also means there is always somewhere to stop and eat something tasty on-the-go.

Stations are generally very clean and safe, by US standards. The issues that one is more likely to encounter are crowding and confusing signage, especially in stations providing transfers between local and regional services. I got lost in a station at least once a day. Luckily, there were staffed ticket gates where I was able to ask a human how to get where I needed to go using a combination of gestures and poorly pronounced location names.


I normally wouldn’t have a lot of reason to observe accessibility, but I happened to be traveling with friends who have a toddler – and thus, a stroller. Practically, that meant we needed elevators. The elevator requirement put another level on the difficulty of station navigation. In our experience, one can almost always find a sign pointing to an elevator from the train platform, but finding an elevator from a mezzanine to a surface-level exit was another matter. There were at least a few times when my weary travel companions settled for carrying the toddler/stroller combo up the stairs. Another obstacle, literally, was the narrowness of the ticket gates that one must pass through at mezzanine level. In most cases, there was a staffed gate with a wide-enough portal, but we did encounter a couple of cases where the stroller simply did not fit and we had to use a different exit on the other side of the station.

To summarize: the train stations are technically accessible, but the large size and complexity of many stations makes the search for elevators a confusing, time-consuming process.

Final Thoughts and Lessons for Seattle

I suspect that one could live an entire life in Japan that is ignorant of asphalt highways, given the massive scope of the regional rail networks. The analogy between the transit hierarchies in Japan (shinkansen > commuter/regional > subway/metro > bus/tram) and the road network hierarchy in the US (interstate > at-grade highway > major arterial > local access/residential street) is striking. If you want to see the logical conclusion of dense urban planning and high capacity transit on a large scale, I highly recommend visiting the Tokyo-Osaka corridor of Japan.

I think there are some takeaways here for our city as we build out the ST3 rail lines in the coming decades. It’s obvious that dense, mixed-use planning with good pedestrian access is very important. There are smaller initiatives too, like colocating retail/commerce with some of our busier stations, that would improve the network. Zach mentions the same point in his report from Mexico City – and I think it bears repeating. A related point is to ensure that the transfer environment is as simple and comfortable as possible for riders. The nature of Japanese transit, with its multiple private operators necessarily occupying different regions of a single train station, leads to a fairly complex transfer. Here is one area where we can actually do better in our city.