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Subject:Traffic engineering angst continues
Time:02:40 pm
These guys are still hard at work installing the new traffic signal at Piedmont and Linda. If you've ever wondered why traffic signals are so expensive, it's not just the cost of materials -- there is also an awful lot of tearing up concrete and digging required to mount and wire them.



One of them confirmed for me that the new signal is going to have pushbutton actuation for pedestrians. It's not their fault. They're just building what the specifications called for. There's probably no malice anywhere -- just someone at the Department of Public Works copying boilerplate specifications that were designed somewhere in the 99% of the area of the country where no one ever walks anywhere beyond the end of their driveway under any circumstances.
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fengshui
Link:(Link)
Time:2010-07-30 09:41 pm (UTC)
Since I haven't heard your rant on this subject, what would you prefer?
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enf
Link:(Link)
Time:2010-07-30 09:51 pm (UTC)
The existing three-way stop works fine as far as I am concerned, but if there is going to be a traffic light, it should be one that gives pedestrians a "walk" signal whenever it gives vehicles going the same direction a green light.
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a_0001
Link:(Link)
Time:2010-07-31 07:37 pm (UTC)
The reason this isn't done is because of the required pedestrian change and buffer intervals, which can be much greater than the yellow change and all-red intervals for vehicular traffic.

For a traffic-actuated signal at a minor street intersecting a major one, the signal timings for vehicular movements on the minor street—and thus the interruptions in traffic flow on the major street—can be very short. The green time need only be long enough for a driver to see it and get started; the yellow change interval can be brief, particularly if the approach speeds are low; and the all-red interval can be omitted entirely. (See section 4D.26 of the 2009 MUTCD.)

In contrast, if the WALKING PERSON indication is shown, the required change interval (flashing UPRAISED HAND) and buffer interval (steady UPRAISED HAND) are potentially much longer. The buffer interval is required to be at least 3 seconds, and the change and buffer intervals have to add to at least the clearance time, which is generally the amount of time required to cross at 3.5 ft/sec having left the curb at the last moment the WALKING PERSON was shown. (See MUTCD Section 4E.06.)

While all this is happening, traffic on the major street is stopped, and if it's a busy street, a queue is building. This added control delay—potentially for both vehicles and pedestrians—is hard to justify unless there was actually a pedestrian present to get some benefit from it, hence the pedestrian detectors.
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enf
Link:(Link)
Time:2010-07-31 08:21 pm (UTC)
Sure, it's the thing to do if you want maximally efficient vehicle flow. But this is a neighborhood center, where vehicle flow is slow and congested no matter what you do, and where any increases in vehicle efficiency, if they can be achieved at all, are in fact to the detriment of the neighborhood. This is a place for humans and the humans should have priority.
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xp84.myopenid.com
Subject:Says you.
Link:(Link)
Time:2011-10-10 05:31 pm (UTC)
increases in vehicle efficiency, if they can be achieved at all, are in fact to the detriment of the neighborhood

Says you. Perhaps if you needed to commute from your neighborhood to a job not accessible by transit, you'd feel otherwise.

This is a place for humans and the humans should have priority.

Some humans use shoes to enhance their commute. Others use cars. All are humans. What makes you so superior?
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enf
Subject:Re: Says you.
Link:(Link)
Time:2011-10-10 06:17 pm (UTC)
Please go away and take your motorism somewhere else. I am doing my damnedest to collect systematic, objective data about where people choose to spend their time, and if one thing is clear, it is that they choose to spend it in places where motor traffic is slow and difficult.
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[icon] Eric Fischer - Traffic engineering angst continues
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