Plessey

Corporate History and Overview

Automatic Years

In November of 1911, British Insulated Cables created a business entity known as the Automatic Telephone Manufacturing Co. of Edge Lane, Liverpool to produce automatic telephone exchanges and related equipment. It will be noted that in 1932, now a subsidiary of International Automatic Telephone Co., Automatic Telephone Manufacturing Company changed their name to Automatic Electric Co. In 1936, they were absorbed back into the parent corporation, adopting the merged name Automatic Telephone and Electric Co. Ltd.

Plessey Takeover

Founded 12th December 1917, Plessey Co. of Marylebone, London was created to produce small mechanical bits and bobs. They would shift into electronics contract manufacture in the 1920’s before dissolving and reforming themselves as the Plessey Co. on 15th February 1925.

In 1960 Automatic Telephone and Electric Co. joined in a consortium with Plessey Co. with five other companies to form a holding company, Combined Telephone Holdings, in an unsuccessful attempt to acquire one of the smallest telephone players, Telephone Manufacturing Co., and later in a successful attempt to acquire another of the smallest, Phoenix Telephone and Electric Works.

Continuing on the trend from 1960, and an eye towards expansion, Plessey ended manufacture of some commercial electronics and focused on shifting from a component manufacturer to a systems provider. Acquisitions of Automatic Telephone and Electric Co. and Ericsson Telephones Ltd. doubled corporate size and made them Britain’s largest telco manufacturer. In 1965 these three would be fully combined, furthermore known as Plessey Telecommunications. Traffic signals would now be only a minor business concern of Plessey, having scores of subsidiary companies and tens of thousands of workers. Later years would see the designs updated one last time before they lost out to more upstart manufacturers such as Mellor and in later years Siemens and PEEK.

Distributors and Contract Manufacturing

In 1932, Automatic Telephone Manufacturing Co. began producing traffic lanterns. Using the trade name Electro-Matic to describe their automatic operation, it is believed they had a cooperative agreement with Automatic Signal of the U.S.A. who were also pioneers in the field of actuated traffic control.

Traffic Signals

broken down into general categories

Design Characteristics

Now referred to as Plesseys or Tin Lanterns, the iconic British Traffic Signal with its jaunty white cap and skirt wearing stripes of black across its face was widely adopted throughout Great Britain by the Ministry of Transport (MoT), local highway authorities, Police, and many other countries throughout Europe (though many of these countries chose alternate color schemes.) Many found their way to the U.S.A., however these are all believed to be souvenirs or war trophies as none have been seen in service to date.

Construction of these signals was very basic when compared to the evolution of U.S.A. signals of these decades. The body itself was formed from two stamped sheets of bright metal giving rise to the term “tin lantern”. One with lenses-sided holes for the front face and bent flanges, a second larger flat sheet formed into a triangle to form the actual body, and both being riveted together to form a triangular tube. The top and bottom end caps were of medium finish quality cast aluminum silicon with inset nuts and studs. The doors were of much finer finish die cast aluminum silicon with heavy aluminum silicon sheet rolled visors attached. Door hinging was achieved by simple L-brackets forming the hinge and studs with plated wing nuts and more L-bracket stampings creating a door latch. Sealing was accomplished through the use of extra thick gasket material around the lenses, no sealing other than overlapping edges was provided at the top and bottom plates. These signals were designed to have a twenty year service life, although it appears many far outlived that in excellent condition.

There was little modularity offered in the design, at a time when most manufacturers were selling sectional signals. All standard visors were available, open type cowls (cap visors), tubular type cowls (tunnel visors), butted tubular type cowls (“full circle” visors), and side projection type cowls (a long tunnel visor with either the right or left side cut away in the style of a cap visor.) The signals were only available in three or one lens size. A special two lens pedestrian model was offered, in the same size as the three lens model, with the amber aspect not installed.

Mounting too, was a simple affair. Designed to be put on a four and a half inch, horizontally zebra striped post, spring steel plates mounted to a stud on the top and bottom plate of the signal which lined up with mounting collars on the post. This allowed a wide range of adjustments in position and direction of a signal – up to two could be mounted facing the same direction, and up to five on a single post. Tilt of a signal head could be accomplished by intermixing various lengths of the mounting plates.

Wiring would go from a common junction box inside this pole through armoured [corrugated] conduit directly to each socket of a lamp aspect inside the signal head. Access to the head was provided by an eave at the top-back of the upper cap plate with a small cord clamp holding the conduit tight.

Recommended placement of these signals was to have two per direction per intersection, minimum. The first, a primary signal, located on the kerb of the traffic it controls. It shall have been placed three feet beyond the stop line for its lane(s) of traffic. A secondary signal should also have been used. The secondary would be placed diagonally and across the street from its lane of traffic. All known examples of these lights were side post mounted, currently no examples of post-top, spanwire, or overhead gantry mast mounting are known. Even today such mountings are much more rare in Europe mostly appearing in newer development regions.

Four Ways

describe models, variations

Adjustables

describe models, variations

Pedestrian Signals

describe models, variations

Vehicle Heads (Round)

describe models, variations

Vehicle Heads (Square Door Adapters)

describe models, variations

Pedestrian/Sign Heads (Rectangular)

describe models, variations

Informational Signals and Signs

describe models, variations [delete] includes "box signs," "case signs," and Ped Heads with special [non-ped] lenses.

Lenses

describe models, variations

Vehicular

describe models, variations

Pedestrian

describe models, variations

Worded

describe models, variations

Symbols

describe models, variations

Special

describe models, variations

Controllers

14 March, 1932 – Cornhill, Bishopsgate, Gracechurch, and Leadenhall, London. First European Electro-Matic intersection is put into service. The cabinet was placed on the northeast corner of Cornhill at Bishopsgate. While the controller is long gone the Victorian era building behind it remains, now a Sainsbury Local.

The common offering traffic controller, with 12Vac vehicle actuation vs. fixed time base controls, was a simple unit that was best suited for four phases or smaller. Larger, and more complex, systems required a larger “compound” controller that contained a discreet “cam shaft unit” for each road tied into that controller.

Override capability was provided to dispatch stations such as fire and police garages allowing them to obtain right-of-way as soon as the minimum green has elapsed for any current phase the intersection is in.

The vehicle actuation system also featured the ability to skip phases or adjust timing based on demand (density control.) Multiple intersection coordination as well as a master driven flexible-progressive coordination system was also in use. A Detector Impulse Repeating System (DIRS) was introduced to allow interconnected intersections to share data about traffic volume along the whole route.

Bias Linking was the newest system introduced in the 1950’s to allow the flexible progressive system to return some local control to each intersection. In this setup, each intersection has its own local controller and detector/demand based rule set to control cycle lengths and priority. All intersections along a route are interconnected to a master controller which regulates the strict phase changes. Where the bias comes in is where one intersection notices that its current right-of-way is not being utilized, the local controller can choose to accept a detector input, or bias, for an out of phase arterial street before reverting back to the phase change sequence demanded by the master. Bias Linking also allowed the detector inputs to be ignored, with the right-of-way phase placed in a hold period. Three separate plans could be stored and used in the interconnected system. In the event of a local controller losing sync with the master, an alarm was raised at the master station and the local controller would function independently in isolation.

A pedestrian push-button system was offered on the controllers, essentially tying a pushbutton into the actuation system and allocating pedestrians their own phase(s) of traffic along with a WAIT/CROSS NOW signal.

Controller Types

Detectors

There were three types of detectors offered for the primary street traffic expected to be controlled, vehicle, tram, and pedestrian.

Road Vehicle Detector Type FS (Flat Strip)

This pneumatic system is designed for use on roads, intended to survive and operate during exposure to steel wheels, stopped vehicles, rain, ice, and tropical sunshine [which required a special formulation of rubber]. Each detector is a pair of oval rubber tubes spaced several inches apart, perpendicular to the flow of travel in a metal channel embedded in the road. Available widths of two to sixteen feet could be used, each two foot section being linked to the next and leveled to the road bed.

These two tubes were connected to a simple mechanical differential pressure switch linked back to the controller. The only other component of this simple system was a Winchester 40 oz. glass bottle used as an expansion chamber, dehumidifier and leak detector via the inclusion of a silica-gel desiccant and humidity indicator strip.

Tram Detector

Tram detectors were a much less complicated affair. Designed for use on the overheads, a trolley passing by would trip a switch on the power lines. This momentary switch would activate a high voltage relay that closes a low voltage circuit, sending a detection signal to the controller.

Pedestrian Push Buttons

The last type of “detector” was the much less automatic, but bog-standard to this day “pedestrian push button.” A completely manual system, a pedestrian approaching an intersection would first take heed of the current traffic flow and signal lamps. Seeing they were not in his favour, he would reach back and depress a large and well marked cast iron push button. This would close a circuit at the controller indicating that a pedestrian phase, or alternate traffic pattern, should be initiated at first opportunity.

Hardware

Ped Buttons

The pedestrian button was a sturdy piece. Engineered for long life, it starts with a cast iron frame secured to a local post with two large U-bolts. A smaller tin containing the button itself and wiring terminations is attached to the frame. Above and below this are mounted vitreous-enamelled steel plates indentifying the button.

Optionally mounted to the same pole is a smaller cast iron bracket and signplate indicating the button is “around the corner.”

Miscellaneous Images

Various reference images, restored examples, etc. that don't fit anywhere else.

Relevant Patents

Patent numbers relevant to this MFR or signals specifically. Not just every patent by company X.

References

http://www.gracesguide.co.uk/Automatic_Telephone_and_Electric_Co

http://www.gracesguide.co.uk/Automatic_Telephone_Manufacturing_Co

“Electro-Matic” Vehicle-Actuated Road Signals, Publication No. 1147, Automatic Telephone & Electric Co. Ltd., 1957

Holding Pen for Unsorted Data, Notes, Etc.

Insert any random discussions here