A Spotter’s Guide to Traffic Signals: Part 2

This is part 2 of the spotter’s guide to traffic signals. In the previous part I covered early Eagle Signal products. This second part continues with their later products and “everybody else”. Once again, I’ve noted “enthusiast / collector slang” by parenthesis to avoid confusion with official designations for products.

Later Eagle models

In 1987 Eagle was bought by a company called Mark IV Industries. Shortly before this Mark IV had also bought out Automatic Signal. Each company had 8” and 12” vehicle and pedestrian signals in poly and aluminum, so a total of 24 products, so simplification was inevitable.The following products survived the merger:

1. Eagle Alusig, 9″ pedestrian only as type SA, later discontinued
2. Eagle DuraSig, 9″ and 12″ pedestrian and 8″ and 12″ vehicle as type SA
3. Automatic polycarbonate, 8″ and 12″ vehicle as type SIG, 8
4. Mark IV aluminum, 12″ pedestrian and 8″ and 12″ vehicle as type SIG, 8″ vehicle later discontinued.

“SIG” is known as “SG” with LEDs, and now can only be ordered that way. Of these types, SA continued to be used in the cities, while Mn/DOT and the suburbs switched to aluminum SIG exclusively, (referred to by enthusiasts as “Bubblebacks”). Mn/DOT finally switched to polycarbonate a few years ago, and suburban agencies followed, so now we’re starting to see type SA in the suburbs.

Siemens bought Mark IV’s signal products in 1997, discontinued the Eagle name, and moved Eagle away from the Quad Cities to Texas. In 2013 Siemens sold Eagle’s signal head business to a company called Brown Traffic (while keeping the more profitable control business). Brown has indicated they plan to re-introduce the Eagle name, and update the molds to the new Eagle logo, which is a realistic perched eagle rather than the stylized “Thunderbird” of the past 50 years. The headquarters has returned to the Quad Cities, although manufacturing will likely stay in Texas.

 

Econolite (and GE) Products

Econolite is based out of California.  They’re most noted by enthusiasts for producing a line of neon pedestrian signals that were ubiquitous in California (now virtually all gone), as well as distinctive looking vehicle signals. They got into the vehicle signal business in the early 1950s when General Electric, one of the early players, changed their design and sold them their old molds (In 1957 GE would exit the business entirely and sell them the remainder). I’ve seen 1950s-early 2000s Econolite products used here; there are some in St. Paul, but they tended to be used more in the suburbs.

GE, and later Econolite 8” signals were rather distinctive in that there were vertical grooves running down the back.  A late 1950s production change was to shorten the grooves so they didn’t go all the way to the end of the section due to water ingress problems. Enthusiasts refer to these as “Groove Back”, “Long Groove” and Short Groove”. The corresponding 12” signals were circular and had a concentric design, “bullet backs”, and could come with either round or square doors. (Econolite models numbers were E31 for 8″, T31 or ST31 for 12″, and C35 or SC35 for a combination, the “S” denoted square doors rather than round) These designs lasted until the early 1980s, when “Buttonback” 12” signals debuted. “Buttonbacks” lasted until the early 2000s. These were the last Econolite products I’ve seen used here.

This setup in operation.

McCain Vehicle Signals

In the past decade or so McCain polycarbonate signals have been showing up. They’re very plain looking, but they do the job. 8″ models are often used  as ramp meters. Except for a smaller size they are identical.

 

Programmable Visibility Signals

In their own category are “programmable visibility” (PV) signals for when it’s desired to only allow it to be seen from a narrow viewpoint, for instance two roads the meet at a sharp angle.

3M Model 131, introduced in 1969, was the first of this design. Rather than a conventional traffic signal bulb (which resembles a standard clear incandescent), these used a compact, high intensity PAR lamps that was accessed from the back. The light from the bulb went through a frosted diffuser, and then a clear optical limiter lens, followed by the acrylic tinted Fresnel lens in the front. The whole assembly could also be tilted at different angles. How it worked is once the light was mounted, you’d go up in a bucket truck and peer through the optical limiter toward the road, seeing an inverted image of the road.  You’d then put a special 3M tape (more or less heavy duty duct tape) on the optical limiter to cover parts of the road you didn’t want to see the light.

Eventually McCain introduced their own PV signal to compete directly with 3M. They looked similar, except for the back (which is actually a re-purposed 8” section) and using standard circular visors. This area was never enthusiastic about them, preferring to support the local company. However competition and declining orders eventually led 3M to discontinue their model in 2007 so for a while McCain was the only PV option.

As a more modern  alternative, a company called Intelight offers “electronically programmable” signals. Basically rather than a few high powered LEDs as used in most signals, there are a large number of standard LEDs in a grid. These can be selectively disabled through software to restrict the visibility, generally done by a smartphone app by a worker in the street. These have large heatsinks on the back and so are hard to mistake for anything else.

 

This concludes the spotters guide. I’ve left out products by a number of companies that have only a miniscule share of the equipment here, but what I have have included amounts to well over 99% of the equipment in service here.