Tag Archives: traffic signals

Chart of the Day: 1929 Signal Schedule and Traffic Flow Diagram

Here’s an insane looking chart from streets.mn alumnus David Levinson’s Transportationist blog, showing a “Typical Signal Schedule and Traffic Flow Diagram, North-South across Market Street, San Francisco (1929) [with a] “green wave” set to 10.5 MPH.” Peep your eyes on this! The complex trade-offs that go into something as seemingly simple as how to program […]

Warrants and Justifications for Traffic Signs

The first two parts of this series dealt with warrants and justifications for traffic signals. Here the series concludes with a discussion of warrants and justifications for signs and other traffic control devices.  Justification for Stop Signs   Let’s go to the Minnesota MUTCD; section 2B.4: .03 YIELD or STOP signs should be used at an […]

Some Unusual Traffic Signals

Another installment in my occasional series on traffic signals: here is random stuff I’ve discovered around the area. Is it a Ball or an Arrow? This intersection of County 81 and Elm Creek Boulevard doesn’t seem to be particularly interesting, but look closer when the light turns green. Then move closer. The green ball magically […]

The Flashing Yellow Arrow and the Yellow Trap

Here is part 3 in my ongoing series of articles on traffic signals. Part 1 covered vehicle signals in general, and part 2  covered left turn indications specifically. This is really a continuation of part 2, so I won’t re-explain some terminology covered there. But flashing yellow arrows are important enough to deserve their own […]

All About Left Turns (Traffic Signal Trivia II)

This is part two of a four part series of “Traffic Signal Trivia”, dealing with some history and interesting facts concerning traffic signals. Part 1 covered vehicle signals in general, but left turns are a whole story in themselves, so here we continue. It didn’t take long after the introduction of traffic signal until left […]

Traffic Signal Trivia

Previously I covered some of the history of the traffic signals in service in the area, as well as how to recognize them in the field. Due to length I didn’t really have time to detour into more of the general history of signals, so I’m taking a chance to do so now.   The […]

17 Minutes, One Red Light Second At A Time

I once had a quite lengthy conversation with a traffic engineer—about seven seconds. We were discussing if an intersection should include no-turn-on-red to increase safety for bicycle riders and pedestrians using an adjacent MUP. The engineer’s concern was that this would delay drivers by an average of seven seconds each. This was fascinating, as it […]

Sunday Summary – July 20, 2014

Everything posted on streets.mn this week linked in one convenient post: Highly visual posts on crossing the street:  Ignore the Red Hand of overregulation, You Don’t Have to Live Like a Refugee (or, how to get off the island), and Speeding Up the Green Line suggesting fixes for “unnecessarily restrictive traffic signals” to keep the train moving […]

Chart of the Day: Bike Compliance and Traffic Signal Design

  The above chart comes from this 2006 study by Portland State University about redesigning a traffic signal to accommodate (and even prioritize) bicycles by offering them a unique “bicycle scramble signal.” The before picture shows most bicyclists “breaking the law” (the part of the chart in light purple). The after picture shows the reverse. Here’s […]