Timing is everything

Chamberpot Days on Lyndale Ave

Many thanks to the Mpls Bike Coalition for last weekend’s Lyndale Open Streets.  It was wonderful to experience a neighborhood commercial street in Minneapolis without having to dodge cars, choke on exhaust and expose eardrums to honking, revving and screeching.  And it was surprising also to experience how wide Lyndale feels north of 31st.  Nowadays when we want to cram landscaped medians, buffered bike lanes, bump-outs, light rail and 6 left turn lanes on every street, Lyndale’s ~60′ seems confiningly narrow.  But in the days when the only thing you put in the street came out of your chamberpot, it must have felt grandiosely wide.  Maybe the reasoning was that if your street was wide enough that no shade reached the middle, the shit would dry out quicker.  Now that our streets are relatively free of shit, I’d like to propose a rule that no street be any wider than can be shaded by, say, a 20 year old boulevard tree.

But I didn’t bring up Open Streets as a launching point for a discussion of the effects of excretory matters on urban physiognomy.  I bring it up because after walking 9/10s of the round trip length of the event it brought me to Common Roots at the precise moment that I was thirsty for a beer and ready to sit down, and Common Roots had free copies of The Wedge, the tiny little newspaper for the confusingly-named Lowry Hill East neighborhood.  And inside that tiny newspaper was a tiny column called Pedestrian Improvements on Hennepin Avenue by CM Tuthill about how the people have spoken and she has listened to “the difficulty pedestrians have crossing streets in Uptown.”  And that column inspired this post, titled with a pun but really a collection of some stuff I’ve wanted to say about traffic signal timing/programming for a while.

Leading pedestrian interval

If you think the salon’s in rough shape, you should see the two pedestrians

CM Tuthill’s column highlights the concrete action Public Works is taking to address the aforementioned pedestrian difficulties – leading pedestrian intervals at the intersections of Hennepin Ave with Lake and Lagoon Sts.  CM Tuthill describes it thusly:

The Leading Pedestrian Interval gives pedestrians the walk signal 3-5 seconds before the green signal for [vehicular] traffic.  Pedestrians get a head start on crossing the street and become established in the crosswalk before vehicles begin moving.

I couldn’t tell from the article whether this pattern is in operation yet, but I’m looking forward to trying them out. These intersections are both terrifying, with the one at Lake infamous for the frequency with which cars crash into the salon at the northeast corner.  My guess is that the biggest improvement will be at Lagoon, where cars turning right from Hennepin to Lagoon were somehow able to see a red light as a green arrow.  Email 311 to tell them how great leading pedestrian intervals are and how they should be used at every intersection with a right turn lane.

Loser pedestrian interval

Push this and hurry

On the other hand, there are still lots of intersections with loser pedestrian intervals.  These give pedestrians a don’t walk hand way before the light turns red.  There is actually a somewhat legitimate reason to do this on a very wide road in order to halt pedestrians when their continued crossing after the signal changes would cut too deep into the next phase.  Almost no streets in Minneapolis and St Paul are wide enough for this and more common are examples like Glenwood & Royalston, at the heart of Minneapolis’ Homeless District. At this fairly narrow street – with a refuge median –  a beg button must be pushed before you even get to suffer the indignity of the signal timing, which gives twice as much time to the don’t walk time as it gives to the walk and flashing don’t walk combined (40 seconds vs 10 and 10).

This leads me to speculate about the causes of this sort of affront to pedestrians.  The beg buttons at Glenwood & Royalston were actually faux buttons until recently.  This means one of two things:

  1. The signal technology is so crude that it only allows certain heinous types of programming (think about the enormous signal cabinets you see at the side of the road to house the computers that control traffic lights and then think about an iPod Nano); or
  2. Someone actually designed it to be this way.

I shudder about equally at each of these possibilities.

Non-conflicting pedestrian walk signal

Last year I reported that only two of the 8-10 protected left turn enabled traffic signals on Hennepin – installed during the two-way conversion just a few years ago – gave walk signs to non-conflicting pedestrian traffic.  There is a good amount of foot traffic downtown, and holding them unnecessarily wasted time and encouraged non-compliance (already a good strategy for pedestrians in a auto-oriented one-way grid system).  The City’s zillion-dollar traffic signal programming initiative has fixed at least a few of those – the signals at 11th & 12th work now, although 9th & 10th still don’t.

Pedestrians crossing the north leg of the intersection conflict with the protected left turn, so they get a don’t walk sign. But thanks to lazy traffic engineers or inept software programmers, so do the pedestrians crossing the the south leg, who don’t conflict with a protected phase.

Same traffic pattern as above, but this time the traffic engineer actually gave some thought to pedestrians and managed to avoid wantonly wasting their time.

Imbecilic pedestrian walk signal

The intersection of 12th & Hennepin is alright now, but for the last few months it did something very unusual.  It managed to give a walk signal to non-conflicting pedestrian traffic, but the walk was active for the same amount of time as the walk for the conflicting pedestrian signal, effectively giving them a loser pedestrian interval.  In other words, the pedestrian traffic that doesn’t conflict with the protected left turn traffic gets the don’t walk signal earlier than the pedestrian traffic that does conflict with protected left turns.

This situation, and the fact that it’s subsequently been fixed, indicates to me that the source of pedestrian signal timing troubles – or “difficulty pedestrians have crossing streets” as CM Tuthill put it – is due primarily to lack of attention by traffic engineers.   It may be that the software used to program signals isn’t what you’d call user-friendly, but clearly it’s possible to program a phasing pattern that’s beneficial to pedestrians.  Let’s hope more policymakers follow CM Tuthill’s lead and put policies in place that would force traffic engineers to learn how to use their software for everyone’s benefit, not just for cars.

A less filthy version of this post appears on streets.mn.

9 comments on “Timing is everything

  1. […] helps focus this post on traffic signal programming, also posted on my blog in a more digressive version.  It was inspired by a column by CM Tuthill in the latest issue of Lowry Hill East’s […]

  2. Janne says:

    The non-conflicting walk signal issue you highlighted for left turns on Hennepin is also an issue at Hennepin and Lagoon. The Lagoon crossing on the east side of Hennepin has a “don’t walk” signal when Lagoon traffic has a red light in order to avoid conflicts with west-turning traffic off of Hennepin. It’s been like this for 16 years (or as long as I’ve lived in the neighborhood).

    • Alex says:

      Thanks for pointing this out. Maybe I’ll start a list – the intersections that don’t give a walk signal for non-conflicting pedestrians outnumber the ones that do, I’ll bet.

  3. Thomas says:

    The leading pedestrian intervals in uptown have been there for at least a few weeks. They work very well, in my experience . . . just need to fix the issue Janne pointed out above, now.

    • Alex says:

      Glad to hear they’re in operation – I’ll have to get down there and try them out.

      Really disappointing that they didn’t fix that issue when they programmed the leading pedestrian interval – maybe the computers are analog (!!!!) but it would have to be really terrible software if they couldn’t easily change both at the same time.

  4. David Greene says:

    > (think about the enormous signal cabinets you see at the side of the road to house the
    > computers that control traffic lights and then think about an iPod Nano)

    I’m a computer engineer and I agree with much of what you have to say but the above isn’t really fair. An IPod doesn’t have to survive all sorts of temperatures, moisture, weather, dirt, people banging on them and so on. Rugged electronics is not an easy thing to do.

    • Alex says:

      That’s a great point. I’ll be the first to admit I don’t know beans about what’s in those cabinets, but I have seen them open, and the metal case is actually as thin as it looks. Meanwhile, you can get a fireproof, waterproof safe for less than $100. Seems like it may be a good trade to spend a bit more on the cladding and less on the guts, at least in dense areas.

  5. […] sarcasm and wit. His posts are funny. Yet, more importantly, they are poignant [for example: here, here, and […]

  6. […] sarcasm and wit. His posts are funny. Yet, more importantly, they are poignant [for example: here, here, and […]

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s