Ever look at a traffic signal and wonder how old it is or who make them? What follows is a two part “spotter’s guide” to the traffic signals of Minnesota. There is a certain slang used by people that are used by enthusiasts and collectors of traffic signals. I’ve included it here since it’s useful to describe and distinguish various models, in all cases it’s enclosed in parenthesis to make it clear that it is not official terminology. Now onto the guide:
Eaglelux KB63 “Tall Fin” and “Short Fin”
The Eagle Signal company is one of of the oldest of the signal companies, located in the Quad Cities for many years. And the oldest signals still in place in Minneapolis are the Eagleluxes, which was the original Eagle trade name for their signals. (This area has long shown a strong preference for their equipment). Although a lot have been discarded in the recent traffic signal timing project, there still are some left, many with incandescent yellow. The most distinguishing feature of them is the art-deco like fins on the top and bottom plate. (Early sectional signals had open tops and bottom to each segment, there’s be an end plate on each end and tie rods holding the entire thing together.)
These were made from the 1930s to the mid-1950s. Early KB63s, the “Tall Fin” have a brass ID tag (normally covered by years of paint) on the bottom plate and no logo on the backs. Later there were running production changes where the fins were noticeably shortened, the Eagle logo was added to the back, and the ID plate was removed, and the fins were noticeably shortened The reason for this is speculated to be that the long fins interfered with more modern mounting hardware that was coming into use. This configuration is known to collectors as the “Short Fin”.
Eagle Rodded Flatback
n the mid 1950s, Eagle dropped the Eaglelux name and introduced the “Rodded Flatback”. This was somewhat of a transition that was only in production for a few years. It introduced the simplified body style that would last for many years, but maintained the use of top and bottom plates, (now with no fins) with tie rods and the older style “slam latch” reflectors, and old small logo. I don’t know of any that are in the field, but list it as there might be, and since it is interesting as a transition to the more modern style. Also of note this is the first that had dedicated 9” square pedestrian housings. Before if you wanted pedestrian indications you added a 4th sections to the vehicle section and installed a black and white circular “Walk” lens, or later on a separate 2-light signal with an orange “Wait” and white “Walk”.
Eagle KB170 / KB380 “Flatback
1960 Eagle introduced this model, Gone are the tie rods and plates, all sections now have tops and bottoms and are held in place by internal clamps, and the reflector was a modern “H” shape. The small Eagle logo was replaced with a much larger version. The initial production had a large trapezoid above and below the eagle, enthusiasts call these these “Trapezoid Flatbacks” and only they only lasted a few years before the trapezoids were removed (the reason for them is not known).
Although the 8″ variety are most common, in the 1950s 12” indications were introduced and promoted by the signal companies as being more visible on the newer higher speed roads and more complicated intersections. Initially only the reds were 12”, and only on overhead mountings (which became increasingly common during that time)- 8” and 12” sections have always been able to fit together. Later all three sections were 12” (and now 8” are only allowed on lower speed roads). Eagle’s version was designated model KB380 and besides the obvious size difference looks similar to the 8”. Some KB380s are found on older installations in Minneapolis and the suburbs, but they are not overly common.
Eagle AluSig and DuraSig
In the early 1970s there was a radical redesign. With catchy trade names came a move to internal hinges, and thumbscrews instead of latches to hold the doors closed. AluSig was made of traditional aluminum, and DuraSig introduced a new material- polycarbonate. Minneapolis and St. Paul were quick to adopt polycarbonate, the other agencies and Mn/DOT were very slow to and only recently have switched. The early DuraSigs had an unfortunate design in that the reflector was attached to the door, which made it difficult to change the reflector or lens, as well as visors attached with fragile tabs instead of screw. They were later revised to a more conventional design. DuraSigs worked well up here where they were immune from salt spray, but tended to bake and become brittle in warmer climates.
Both 8” and 12” DuraSigs were wildly popular in the cities, and the 12” versions are still being installed. AluSigs were more popular with MnDOT and the suburbs, even then they were mainly using 12”, so 8” AluSigs are uncommon, and when found are normally a pedestrian signal or the yellow and green of a larger assembly.
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:
- Eagle Alusig, 9″ pedestrian only as type SA, later discontinued
- Eagle DuraSig, 9″ and 12″ pedestrian and 8″ and 12″ vehicle as type SA
- Automatic polycarbonate, 8″ and 12″ vehicle as type SIG, 8
- 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”). MnDOT 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. They’ve now renamed themselves as MoboTrex, The poly SA and poly and aluminum SG both remain in production.
GE and Econolite 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.
McCain
In the past decade or so McCain polycarbonate signals have been showing up. They’re very plain looking, but they do the job
Programmable Visibility Traffic 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.
ventually 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 offerED “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. Unfortunately after they switched production to China, shoddy quality let to problems with water infiltration that would destroy the electronics, and they never managed to solve the issue, instead discontinuing the product in favor of focussing on their traffic controller business.
8″ Lenses
The makers of traffic signal housings always subcontracted out their lenses to one of the two of the country’s glass manufacturers- Kopp, Corning, and Holophane
Holophane “Spiderweb”
In my personal opinion the most beautiful of lenses, collectors and enthusiasts refer to these as “Spiderwebs” due to the obvious resemblance. These were used exclusively on 1940s era GE signals. Siemens adapted a very similar design for Europe where they are very common. BVut in the US these, not lasting long and used by only one manufacturer, are somewhat rare. A set of these usually fetches over $300 on the collectors market.
Corning “Smiley Face” Type T and T-1
The earliest lenses that are still occasionally seen in some areas of the country (but never in MInnesota) are the Corning T and T-1. Known as “Smiley Face” due to the distinctive pattern designed to throw light downward for the benefit of vehicles and pedestrians near the intersections when the signal was mounted on overhead wires. There was an earlier version with larger beads, but it was revised once ITE standards came out which regulated the light output of lenses. Although distinctive, the later version isn’t especially rare, the CH “art deco” signals were extremely popular back in the day and as are desirable to collectors and thus many have been preserved when they’ve come down.
Corning T-3
The T-3 was used mainly in later Crouse-Hinds signals, some of the later ones are (apparently) mis-labled as 1-3. There was also the T2, the “Faint Smiley” that maintained the ribbed outline of the original “Smileys” but not the beads.
Kopp “Brick” lenses (TL-4655 and TL-4955)
Following the “Spiderwebs”, GE again commissioned their own design with their own logo, commonly called the “Brick” pattern. This was later adopted by Econolite when they bought out GE’s signal business. All but the oldest GEs and all but the oldest and newest Econolites will have this pattern, including all in the time frame that they were used in the Twin Cities.
Kopp “Sawtooth” lenses. (TL-4677 and TL-4777)
Smaller manufactures would typically use “Sawtooth” lenses so they are extremely common in other areas of the country, but Minnesota has always shown a preference for Eagle and to a lesser extent Econolite, both of which used their own patterns.
Eagle Lenses (Kopp 88, 88.1, and 88A)
Very early Eagles would be equipped with generic lenses, but Eagles own design, the Kopp 88 series, came in the 1940s and the same basic design was used by them until the end of the glass lens era. Although the pattern was not that distinctive, they featured Eagle’s logo and are by far the most common 8″ glass lens still in the area (often in the yellow sections of older Minneapolis signals). Earlier models have the “Stop and Go” logo while later models have the “Thunderbird” logo.
Polycarbonate Lenses
With the coming of polycabonate signals came polycarbonate lenses (although aluminum signals could also be ordered with them, and polycarbonate signals could also be ordered with glass. These tended not to last, they’d oxidize in the weather, and get scorched when used with higher wattage bulbs that were on a lot, like main street greens or side street reds.
12″ Lenses
Generic Poly Lenses
12″ signals tend to mostly have polycarbonate lenses. Here’s a typical red
3M Lenses
Lenses for the 3M Model 131 signals were square plastic with a Fresnel pattern. Balls or arrows were stenciled out.
LED modules
Early Designs
The first LED modules were actually designed to utilize existing sockets, reflectors, and lenses, and were initially available in red only. the primary companies making them were Electro-Techs, Ecolux (later bought by GE), Cooper (which was popular in New York but exited the business, Dialight, Leotek, EOI, and Swarco.
The earlier modules all had the individual LEDs exposed, this is from Leotek. Dialight and Cooper were arranged in circles rather than rows.
GE RX11
These were an attempt to compete with the later emerging “Incandescent Look” or “Uniform Look” designs while using the older technology of arrays of many low-power LEDs by putting a diffuser lens on top to spread the light. There’s a lot of these in the Twin Cities, but they have not held up well, are now reaching the end of their life with many partial failures, and tend not to be liked by collectors.
Ecolux / GE “Honeycomb”
These were a variation of the exposed LED modules with a small magnifying lens over each LED. There are a number of these still in Minneapolis and St. Paul and they tend to outlast even the newer RX-11s.
“Incandescent Look” Diamond Pattern
WIth improvements in LED emitter design, it was now possible to light a traffic signal with a few powerful emitters placed at the rear of the housing, which backlit a plastic lens rather than viewing the LEDs directly. These were called the “uniform look” or “incandescent look”
Later Incandescent Look
New GE Incandescent look module with the lenses removed- a fresnal lens, a beaded lens, and a clear outer lens (that’s tinted if so ordered)
