Episode 18 – Red on Top

Topics: Red on Top, Traveling with a Traffic Engineer

Talking Traffic Episode 18 – Red on Top

Hello and welcome to Talking Traffic episode 18. My name is Bill Ruhsam and I produce this podcast and its sister website, Talking Traffic.org. Today is Tuesday April 1st. and this is not a joke.

My wife is a professor of technical communication at Georgia State University. She has a conference this week in New Orleans that I’m tagging along for. We live in Atlanta, so New Orleans is within driving distance, plus I want to see some of the country side between here and there on the trip. Unfortunately, this is going to give her more opportunity to dislike travelling with me by car. You see, ever since becoming a traffic engineer, I can’t driver in other parts of the country without, inevitably, making commentary about the signing or striping, or roadways in general. I’m especially bad nowadays when driving through construction zones, evaluating the ways they are constructing a project, or protecting the workers, or setting up the erosion control. I try to keep my color commentary to a minimum, but sometimes my inner geek flows forth with greatness and she’s forced to listen to me vent about engineering.

This wouldn’t be the case if everything were done the same way in all parts of the country, but then it wouldn’t be a very fun place to live if we all did things exactly the same way. I’m not denigrating conformity when it comes to things like Stop Signs being red, but there are plenty of areas where different policies can lead to different looking roadway environments. This makes travel interesting, in my opinion.

Some things, though must be the same, no matter where you go, or you end up confusing the driver and raising the potential for serious collisions. The Stop Sign color I just mentioned is one of them. No matter where you go in the United States, Stop Signs are red with white lettering. If they’re not, then they must be privately installed because no public entity would put up anything by a white on red stop sign. Similarly, all warning signs are yellow, and construction signs are orange. These requirements are intended to provide a common driving environment and to avoid surprising situations. These policies are laid out in the Manual on Uniform Traffic Control Devices, or MUTCD, which I talked about in Episode 9. That episode was devoted to signs and striping, this one will talk about signals.

Traffic signals are also subject to the MUTCD. As a quick refresher for those of you who haven’t listed to Episode 9, the MUTCD is a set of Federally Mandated Guidelines that must be followed when installing traffic control devices. I say, “mandated”, but really what it means is that if you don’t follow the rules in the MUTCD, you will lose any potential federal funding, and you also open yourself wide open for lawsuits if someone wrecks their car. The MUTCD is the playbook, and everyone int eh US should be following it.

For signals, chapter 4 of the MUTCD, which is linked in the show notes if you want to go read it, contains umpteen different rules regarding how to set up a signal, where it can be placed, what color the lights can be, how far above the road to put them, how far back from the stop bar, and whether or not one should be installed in the first place. Today, I’m going to discuss briefly how the signal lights are arranged.

First a little vocabulary to make things easier. When I or someone in the traffic engineering field says, “Signal Head” we are referring to the whole shebang that is hanging from a cable or a metal pole, including the red, yellow, and green lights, as well as any green, red, or yellow arrows. “Signal Heads” includes two or more signal sections. A section is one lamp, whatever color it is. These are also called signal faces. For yet more information, we refer to the normal, round, circular lights as “balls” or “circular” and the arrows as, well, arrows. So, if someone says “make sure you yield on green ball” they’re basically saying, don’t drive through that there green light unless you yield to any other drivers, first.

The MUTCD lays out in very specific detail, the arrangement of the red-yellow-green lights in both vertical and horizontal signal heads. For example, red is always on top in vertical signal heads and to the left in horizontal ones. If you only have red-yellow-green ball, then it’s just that way from top to bottom or left to right in horizontal signal heads. If you add arrows, whether they are green or yellow or red, then they also have very specific positions in signal heads. If you want to see what the positioning is, go to the show notes and click on the link which will take you to the diagram in the MUTCD.

It’s very very important that signal heads have the signal faces within them positioned the same way, all the time, everywhere. The reason it’s important is so that if you glance up and see a light at the top or the left of a signal head, your conditioned response is STOP! This is also important for people who are dichromaticly color blind. About 1% of the male population cannot reliably distinguish between red and green, but they can tellif the lamp is lit on the top or the bottom, thus the standardized position of signal faces.

There is at least one place in the US that violates this rule, though. The Tipperary Hill neighborhood in Syracuse NY contains a signal head which has green on top and red on the bottom. Apparently, this is a highly Irish community and when the signal was first installed, the local ruffians objected to having the color red over the color green, referring to the English occupation of northern Ireland. The signal head was broken repeatedly and eventually the signal was inverted. This is still the case as of a few weeks ago when I personally called the number listed on the Tipperary Hill neighborhood association to see if the signal were still upside down. I asked the woman I spoke with how they got away with it, and she didn’t have an answer. I’m not trying to make anyone’s life difficult, so I haven’t pursued the subject, but I’m exceptionally curious who is in charge of this signal and what measures they’ve taken to cover themselves from a liability perspective. The very first thing I would do if I were hired as the city traffic engineer for Syracuse would be to request a waiver of liability from the city council. Of course, If you listened to my episode about Professional Engineers and their responsibilities, you’ll know that, as a PE, no matter what pieces of paper are in your possession, you are still liable for deficiencies which you know about. That signal represents a potentially deadly situation for color-blind individuals, or just someone who’s squinting into the sun.

The inspiration for this Red on Top episode came from Taylor, the 13 year old daughter of my boss. She asked him why the red light was on the top of the signal. He didn’t know but told her that he would ask me. After he asked the question I said, “well, ummm…gee…ahhh…no idea.” I had to confess that I had no knowledge of the history of the signal head arrangement. Thankfully, I’m a member of a large traffic engineering email listserv and I posted my question to the list. What it all boiled down to was, Red is on top because that’s the way it was decided back in 1930. There isn’t any historical documentation for this decision, but the consensus believes that it’s because Red was considered more important and therefore needed a prominient place. Thus Red on Top. Thanks, Taylor, for the topic.

This episode of talking traffic is released under a creative commons 3.0 attribution non-commercial, no derivatives license. If you like what you heard, or know someone who lives in Syracuse, feel free to duplicate and distribute the podcast as much as you want. Just please don’t’ change it, or sell it, and make sure to credit me and talkingtraffic.org. All opinions in this podcast are my own, including the one that I think the Tipperary Neighborhood is nuts for maintaining that upside down traffic signal. If you live in the Tipperary Neighborhood and think I’m a nut for thinking you’re nuts, send an email to Bill at Talkingtraffic.org, or just leave a comment on the show notes. I’m very curious about the collision history at that traffic signal.

The music you heard on this podcast is by Five Star Fall and can be found at Magnatune.com.

As I said, I’m going to be in New Orleans next week, so perhaps I’ll be inspired with relevant topics out of the Big Easy. You’ll have to tune in to find out. Until then, have a great week.

Theme Music: Five Star Fall, Mercurial Girl, Magnatune.com
Episode 9 – MUTCD
Part 4 of the MUTCD: Signals

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3 Responses to Episode 18 – Red on Top

  1. Pingback: A Short Way to Tipperary. by Schierer Space

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