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Beyond “Transit Scores”: an Exchange with Matt Lerner

Posted on January 24, 2011 in Maps, Mobility, Public Outreach, Technophilia

Matt Lerner of WalkScore.com and I recently exchanged emails about WalkScore’s “Transit Score” product, which provides a two-digit score supposedly capturing the usefulness of transit at any address in the USA.  It’s designed on analogy to the successful (if still controversial) Walk Score, a similar tool for summarizing how friendly a place is to walking.  For example, 300 Turk Street, San Francisco is scored 100 (perfect) on both Walk Score and Transit Score.

Transit score 300 turk

Toward another extreme, here’s 7000 Lake Mead Blvd in the far east of Las Vegas.  Walkscore is 52, Transit Score is 33.

Las vegas walkscore

Tools like these have huge potential relevance to the real estate industry, and more broadly to anyone who makes locational decisions about anything.  To the extent that we encourage people who value transit to locate where good transit is viable, everyone wins.

Earlier, Matt’s team had created a “transit travel time tool” which can be used to show you the actual area you can get to in a specified amount of time.  I used this tool as the core of my definition of mobility, in one of this blog’s earliest posts.

GoogEarth walkscore

So which is more useful, the simple two-digit Transit Score, or an actual map of where you can get to in a given time?

Here’s what I wrote to Matt:

Dear Matt,

About a year ago I mentioned your transit [travel time] tool as a useful way to visualize mobility …

The first draft of the book I’m writing … praises this WalkScore tool in some detail, as a way for people to understand the degree of freedom that transit will offer them.  I think it may be a crucial tool for helping people see beyond modal fetishes to understand how transit actually works and how to determine if transit can actually get you where you’re going.

…  Transit Score is useless to me because it encodes an intrinsic bias toward rail modes, as though rail is intrinsically faster, which is utterly misleading in a world of 6.5 mph streetcars and 60 mph busways.  [I’m referring to the Transit Score methodology’s use of a “mode weight” defined as “(heavy/light rail is weighted 2X, ferry/cable car/other are 1.5X, and bus is 1X)”.  Note that unlike the travel time tool, Transit Score lacks a way to capture how far you can get how fast, so it uses mode as a proxy for speed, fatally in my view.]

In short, whereas the earlier tool presented raw information in a compelling way that the user could use for her own purposes, Transit Score contains value judgments (“we know you’d rather ride a slow streetcar than an express bus”) which the user may not share, and thus may be an obstacle to her ability to make transit meet her needs.

So I guess I will praise mapnificent.net instead.

This issue sits at the very foundation of my current book, so as an admirer of your work, I’d like a better understanding of why you abandoned the original accessbility tool. Was it a matter of the processing required to do what’s basically a massive search of trip planners?  I can see that Transit Score is a much faster calculation, but wonder if that was the key issue.

All the best for ’11,

Jarrett Walker

Matt replied:

HI Jarrett,

Good to hear from you.

You’re right that we are promoting Transit Score over Transit Time Maps — but we haven’t abandoned the transit time maps.  We are working on new ways to use them and they are still available here: http://www.walkscore.com/transit-map.php).

Here’s why we’ve been promoting Transit Score more heavily.  Our mission is to promote walkable/transit friendly neighborhoods and we think the best way to do this is to have Walk Score / Transit Score on real estate listings.

As we developed Transit Score we looked at a few methods of calculating a Transit Score.  The two finalists were our current method (detailed here) and a method where we summed the Walk Score under the area of the transit shed in our Transit Time Maps.  In practice, the scores were very similar between the two methods so we chose the current method which is much easier to scale (we show millions of scores per day).

We want to boil down transit access into a score so that it can appear on real estate listings and people can compare locations.  ZipRealty.com has added our Transit Score to millions of listings and we have some more partners on the way.

We did not see a lot of consumer/partner interest in the transit time maps — which is unfortunate because of course I love them.  One scenario I’m hoping to promote with our Transit Time Maps (we just need a partner) is to allow people on real estate sites to search by transit time.  E.G. find me an apartment within 30 minutes of work on transit.  I’d also like to integrate the transit sheds into the standard Walk Score experience.

I like the simplification Mapnificent made which was to not include walking time in their transit sheds — this makes it much easier to compute.

So to sum up, I like your suggestion of avoiding any mode weight value judgments — it just turns out that in practice our current method was very similar and easier to scale. Anyway, would love to hear your thoughts on this.

Also, we’re launching a beta of “Street Smart” Walk Score later this month and we’d love your feedback on that too.

Happy New Year!
Matt

To which I replied:

Matt

Thanks!  … Suppose, hypothetically, that you had the processing power and datasets to run a purely mobility-based Transit Score.  Let’s call it a Transit Mobility Score.  The algorithm would be something like:  Identify the area reachable in 30 minutes on transit from the selected point (I choose this because it seems to have a long history as an acceptable commute time).  Then, grab the MPO’s database of population and jobs by small zone and calculate the percentage of the region’s jobs and population that are in that 30 minute band.

That also gives you a 2-digit number, but now it’s a fact rather than a score.  You’re saying: “If you locate here, you’ll have convenient transit access to __% of the region’s activity.”  And that strikes me as something that a realtor could value, understand and explain.  How far are you (or someone) from being able to do that kind of algorithm?  Obviously you’d need to have the MPO on your side, so start with somewhere like Portland where they generally are.

Frankly, you’d probably want to do two such scores, one based on your mobility at 8:00 AM and another for your all-day mobility — say, at 1:00 PM.  But I think a realtor could make sense of those too.  Everyone understands that transit in the peak is different from midday, and that both matter.  Suburban areas, especially those under the influence of commuter rail and commuter express buses would show quite a difference between the two.

I think this could be huge.  Because the output is a fact, not a judgment. …

All the best, Jarrett

Matt replies that this “sounds like an awesome planning tool and one we could potentially pursue if we had a grant or something to fund it.”

I still think this could be huge.  What if everyone making a locational decision could go to something like the WalkScore travel time tool or Mapnificent and see a map of where they’ll be able to get to in 30 mintues on transit?  It would finally make our mobility visible.

And if we could measure our mobility so accurately, for so many hypothetical cases, we just might value actual mobility more, and be less distracted by unreliable symbols of mobility — like, say, whether there are rails in the street.  Technophiles shouldn’t be too alarmed; many people will still have modal preferences.  But meanwhile, those of us who just want mobility would be able to measure it, fast, for anywhere that we might be locating something, including our homes.

information request: peaking patterns

Posted on January 23, 2011 in Information Requests

The book is coming along.  Expect a number of information requests in the next weeks, as I start pinning down details.

I need some nice charts showing ridership per hour of the day for a typical inner-city transit line, and for an outer-suburban one.  Very simple bar or line graphs, covering a weekday, that I can use to illustrate the fact that outer-suburban service tends to be much more peaked and inner-city service busier all across the day.  If you're inside a transit agency and have access to such things, I'd appreciate it. 

basics: conceptual triangles

Posted on January 23, 2011 in Basics, Density

Sometimes, we have to think in triangles.

In the transit world, for example, we know that ridership arises from a relationship between urban form (including density and walkability) and the quantity of service provided.  For example, if we focus on local-stop transit, the triangle looks like this: Continue Reading →

can you balance california’s budget?

Posted on January 21, 2011 in Public Outreach

Bravo to the Los Angeles Times for this California Budget Balancer "game".

I've long believed that the only way to nurture a civilized democracy is to give voters the opportunity to struggle with the real choices that government faces.  My own work has included developing games and decision tools that enable communities to think about their choices in transport and urban form. 

Budget balancers bring the same principle to the hard choices that are expressed in a government budget.  Everyone's balanced a household budget, or at least monitored their spending and seen its consequences. 

Yes, they contain a million assumptions and simplifications, but once you've played with them you may well ask:  "And why does the real thing need to be so complicated?"   Good question. 

bicycle vs transit problems

Posted on January 19, 2011 in Cycling, Pedestrians, Portland, Seattle, Streetcars (Trams)

Bicycles have always had an anxious relationship with local-stop street-running transit, both bus and streetcar.  On a street without separate bike lanes, bikes and local-stop transit tend to end up sharing the "slow" traffic lane — typically a lane that's either next to the curb or next to a row of parked cars.  The difficulty lies not just in the obvious ability of rail tracks to throw a cyclist, but more generally in the fact that many cyclists like to move at something close to the average speed of local-stop transit — generally 10-20 mph.  With buses at least, the pattern is often for a local bus and a cyclist to "leapfrog," passing each other over and over, an uncomfortable and mildly risky move for both parties. 

Streetcars are much less likely to pass a cyclist than a bus is, and this, come to think of it, may be one of the many little reasons that streetcars often end up being slower than buses when you control for other differences (in right of way, fare handling, signaling, enforcement, etc).  Cyclist friends have often told me that they prefer cycling alongside streetcars rather than buses becuase streetcars don't make surprising lateral moves.  This is true, though of course the lateral motion of buses is a normal part of how they get through traffic, and how they often keep moving in situations where a streetcar would get stuck.

Mia Birk has a good article today arguing that bicycles and streetcars can be friends.  So far, though, the only examples she cites of really successful bicycle-transit integration are from streets where there's plenty of space to separate the two modes, such as Portland's King/Grand couplet.  She's involved now in a consulting team looking at how streetcars will interact with cyclists along a proposed line on Seattle's Broadway, and I look forward to seeing what they come up with. 

Birk is clear that the basic design of the starter streetcar lines in Portland in Seattle — operation in the right-hand (slow) lane next to a row of parked cars — didn't provide good options for cyclists needing to avoid the hazard of the streetcar tracks.  She wants to see better separation, but when looking at a dense urban street like Seattle's Broadway, it's hard to see how they'll deliver that without undermining either on-street parking or pedestrian circulation.  She notes one situation in Portland (14th & Lovejoy) where the streetcar-cyclist conflict was arguably resolved at the pedestrian's expense:

14th-and-Lovejoy
… and she's clear that this isn't the outcome she's after.  (This idea of a bike lane that passes between a transit stop and the sidewalk is common in the Netherlands.  It can work well as long as there's ample sidewalk width.  It's less nice in situations like this one where the remaining sidewalk is constrained.)

If I sound a little cynical about the prospects for harmony between local-stop transit and cyclists, it's because this is a geometry problem, and geometry tends to endure in the face of even the most brilliant innovation.  The examples in Mia's post seem to confirm that if the street is wide enough, it's easy to separate cycles and transit, but that if it isn't, it isn't. 

When the problem is this simple, it's not hard to reach a point where you're sure you've exhausted all the geometric possibilities.  At that point, you to make hard choices about competing goods, producing something that all sides will see as a compromise.  Hoping for new innovative solutions can become a distraction at that point, since no innovation in human history has ever changed a fact of geometry. 

Finally, if a streetcar ever does go down Seattle's Broadway, it had better be compatible with buses as well.  Broadway is an important link in the frequent transit network, with lines that extend far beyond the local area and thus make direct links that a starter streetcar line cannot replace.  What will happen to these buses?  If they share the streetcar lane, what will their role be in the streetcar-bicycle dance?

Photo: Mia Birk

brisbane: the last on the flood

Posted on January 17, 2011 in Brisbane

Yes, it appears that many of Brisbane's ferry terminals are gone …

420newfarm-420x0

… but the boats themselves were saved.  Buses are replacing ferries, we're told, though buses can't do much without bridges.

Floods this major don't often happen in developed-world cities.  If you're interested in the recriminations phase, Kerwin Datu has a good overview in the Global Urbanist.

Photo: Robert Shakespeare, Brisbane Times

 

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