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Entering the first work week with ULink open and the Link Connections restructures in place, there will be a flood of anecdotes about whether or not the changes are working. Eventually, ridership numbers will serve as a more concrete measurement of the efficacy of the changes to the transit network. Until then, it’s still possible to take some cursory measurements of the potential for rider benefit using the isochrone map generator that I posted on the blog two weeks ago. Whether these measurements of transit network potential measure anything real and important is another story. You be the judge!

Below are three sets of two maps apiece. As a recap of how these maps work:

  1. They’re centered at a single starting point.
  2. If a bus stop can be reached within 30 minutes by some combination of public transit and walking, there’s a dot at that point.
  3. The color of the dot depends on how many times of day that one could start at the starting point and reach that point. This is in rainbow order, with bright red signifying small numbers and dark violet signifying high numbers.

The first map in each set is generated over the full day of March 17, before the opening of ULink. The second map in each set is generated over the full day of March 31. For each map, two “scores” are included. The first is a counter of the number of stations reached. The second sums the number of times per day each station can be reached, thus favoring networks that allow a broad number of destinations to be reached regardless of the time of day. Both of these scores are fairly flawed, but can be useful when used comparatively and viewed with healthy skepticism. Let’s get to the data:

Start point: Capitol Hill Station

Before: static map; station count: 1774 weighted count: 994130

After: static map; station count: 2375 weighted count: 1291599

Scrollable, zoomable maps (your browser may hate you for this)

Given 30 minutes of transportation time, reaching UW from Capitol Hill was reasonably achievable (at least according to published schedules) before ULink. While improving upon this already good reachability, what really shines through is how much more feasible it is to reach points north and west of the university within 30 minutes. A similar pattern holds for downtown: reaching it within 30 minutes was already nearly a given, but shaving time off the journey allows better chances of reaching West Seattle, not to mention the destinations directly served by the Link. One thing I specifically wanted to observe was any impact of the reduction of the 43 bus. This map shows improved reachability in its corridor, but might not tell the whole story: 30 minutes seems like a generous time allowance for Capitol Hill to Montlake and this map says nothing about reaching downtown from Montlake. But those are maps for another day.

Start Point: UW Station

Before: static map; station count: 2014 weighted count: 758513

After: static map; station count: 2543 weighted count: 1324769

Scrollable, zoomable maps (your browser definitely hates you now)

The weighted count score and the map both make it easy to see a large increase in destinations reachable within 30 minutes. Even with suboptimal station placement, the bus connections appear to work well enough to make locations varying from Lake City to Sand Point to Westlake reachable at many more times in the day. The reachability improvement to downtown is staggering, though it is important to keep in mind that this map does not measure reachability from a portion of the campus where the now-truncated 70-series expresses had a nearby stop. Again, a map for another day.

Start Point: Beacon Hill Station

Before: static map; station count: 1912 weighted count: 989892

After: static map; station count: 1891 weighted count: 1015671

Scrollable, zoomable maps (your browser would have already killed you, but ran out of memory to do so)

I generated this map because I wanted to show the impact of ULink and Link Connections in a neighborhood to which they did not directly pertain, and I already had an existing Beacon Hill Station map. (The limiting factor on why I can’t be generating these maps every second of every day is a daily quota on looking up the walking distance between locations.) There’s a marked improvement in reaching the immediate vicinity of the new stations. The spread of improved reachability around them is weaker than I expected, but I would want to do more analysis before ascribing this to bad bus connections rather than simply running out of time taking the Link. Another interesting component is the decreased station count score. I suspect this is merely the result of some adjustment of the Link schedule so that it no longer aligns as perfectly with some runs of the 41 and 11 buses.

I am hoping to generate more of these comparative maps in the next couple of days. If you’d like one of your neighborhood, give it a shout out in the comments and I’ll do the best I can. I’d also be interested in any comments or issues with methodology or results; if you find this week that this data doesn’t match your observations, we ought to work together to figure out why!

4 Replies to “Measuring the potential of ULink and Link Connections”

  1. It would be very interesting if the “before” targeted March 24, rather than March 17. That way, we could see the effect of the changes in the bus network, isolated from the improvements to Link itself.

    Also, if OneBusAway archives historical real-time progress data of routes, it might be interesting to generate the isochromes based on real arrival data, rather than static schedule data. It is here that the reliability of the routes starts to become very key – for instance, if a bus is scheduled to run every 15 minutes, but, practice, shows up in bunches of two every 30 minutes, the static isochrome would look noticeably better than the real-time isochrome.

    In fact, one could even imagine an isochrome that is based off the longest travel time starting at a fixed time of day between Monday, March 28 and Friday, April 1. The idea being to illustrate how many times a day can you leave the starting point and really trust that you will get to the destination point within 30 minutes. I would be very much interested to see how well a “reliability-based” isochrome can capture the value of changes like the splitting of the 8 and 48, which consume real service-hours, but whose benefit is unlikely to show up in a performance metric that is calculated solely on raw schedule data.

  2. These maps are really cool. Yes, this could be very useful to someone who is confused about the changes. This morning in the bus tunnel, I saw a lady talking to a Metro employee about how to get to where she usually goes. The metro person said “Just get on the train to UW, ride it to the last stop, then transfer to the 72. Makes sense?” to which her reply was “No, that doesn’t make sense.” Of course, for some people, a map with a bunch of colored dots may not make sense either, but it at least helps.

    What I really want to see is what the maps look like after East Link opens in 2023. At that point, light rail will have crossing spines, and form some semblance of a grid.

    1. Well, given that the 72 no longer exists…

      (And the transfer to the 372 isn’t so intuitive, either.)

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