Willis Lamm's
Traffic Signal Collection

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Marbelite 4-Way Signal

Part Three

Once all the wiring checked out it was time to install the Presto-Brite sign box. Presto Brites were common in Seattle as many of the 4-way signals had illuminated signs hanging underneath. Each side of the Presto Brite was 12" x 18" and the panels were made of translucent fiberglass. Inside the top of the Presto-Brites are four sockets in which standard 69 watt signal bulbs were installed. The four lamps provided relatively uniform illumination of the sign panels and also provided redundancy should any of them burn out.

Up and running.

Using the scaffold to hang the light. "Inside view" of the Presto Brite.

Final power check once the signal was wired to the controller. Finished project.

Since the Presto Brite box already had "ONE WAY" indications on two sides and I had planned to light up the Marbelite on all four sides, I decided to make configure it as a signal where a two-way street becomes a one-way street. I lettered the south face of the Presto Lite box "DO NOT ENTER" and replaced the Corning lens with a Kopp 4620-8 crosshatch embossed double arrow. Mote: Some photos have been added of signals still in service with Presto Brite sign boxes attached. They can be found on the Presto Brite page.