Timing is everything – rated G

Bowdlerization 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 neighborhood newspaper The Wedge, which has some great news about changes to signal timing at a couple key Uptown intersections.  I follow with discussions of a few more types of signal programming that affect pedestrians, and I can’t help speculating on the source of certain signal frustrations.  Without further ado:

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 reports of “the difficulty pedestrians have crossing streets in Uptown” – 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.

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7 Responses to Timing is everything – rated G

  1. pedro June 15, 2012 at 7:42 am #

    Even if you didn't write "shit" in this version, can I still write it in my comment?

    Thanks for your observations and thoughts. It's good to know where specific conflicts happen between pedestrians and timing signals. I am (tentatively) a new member of the Minneapolis Pedestrian Advisory Committee. I attended the June meeting, and the Uptown signal changes were discussed.

    Given the fact that street design and signal timing are the factors the the PAC seems to have the most direct line of sight into, I'm glad to know that these issues exist on Hennepin. I wasn't previously aware of them since I usually travel Hennepin by bike and my attention is focused on trying to ride with the traffic flow so I don't become a red smear on the green street paint.

    I do know that the PAC will be actively engaging Public Works to improve signal timing. The Programs and Policies Subcommittee presented a draft resolution that includes the following to the full committee:

    "[The PAC recommends that] DPW . . . extend the walk phase and clearance interval to the length of the concurrent green phase for vehicles, at all signals where the vehicle green phase exceeds the minimum pedestrian crossing times to maximize time allotted and opportunity for safe crossing and exceptions documented with valid rationale based upon engineering study."

    I believe the resolution was passed as proposed. It obviously doesn't address signals in which the green phase doesn't exceed the pedestrian crossing interval, but it's a start. It'll be interesting to see DPW's response. Keep me posted on your observations on signal timing over the coming months.

    Another needed recommendation that was passed out of this subcommittee and approved by the full committee is to recommend that all intersections on Nicollet Mall be equipped with APS signals. Because crossing cross streets is common during red lights, people who are visually impaired rn the risk of being hit by traffic since other pedestrians are currently their only cues for when to cross.

    • pedro June 15, 2012 at 7:57 am #

      And from committee members in the know, it sounds like DPW will be very receptive to the Nicollet Mall signal retrofit, at least.

      • Alex June 18, 2012 at 3:29 am #

        Thanks for the info – that's great news about that resolution. Dunno if the PAC can do this, but it would be nice if it could be forwarded to the city council, so that Public Works doesn't have the option of ignoring it. Also, concurrent is a great word that would have been really useful for my post.

        Streets.mn doesn't censor – you can write whatever shit you want on here.

  2. Evan Roberts
    Evan June 15, 2012 at 3:13 pm #

    It would be lovely if minneapolis had some intersections where pedestrians could cross diagonally. the "barnes dance". So civilized.

  3. Sam Newberg
    Sam Newberg June 16, 2012 at 7:32 am #

    I'd love to see Leading Pedestrian Intervals at crossings of Hiawatha near LRT stations, primarily 38th and 46th Street. Perhaps this can be part of the effort by Hennepin County to improve thos crossings.

    • pedro June 20, 2012 at 2:48 am #

      Great suggestion Sam. Thanks for placing these intersections on my radar.

  4. Sam Newberg
    Sam Newberg June 18, 2012 at 3:39 am #

    I drove through Uptown this past weekend and saw a great number of people taking advantage of the Leading Pedestrian Inverals there. They're grrrrreat!

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