What critical component did the 1914 two-color electric signal system typically lack?

Answer

The crucial intermediary signal (caution/warning stage)

The early 1914 system was simplistic, typically featuring only red for stop and green for go, and it did not possess the sophistication needed for complex intersections, lacking the crucial intermediary signal we now rely upon.

What critical component did the 1914 two-color electric signal system typically lack?

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The Man Behind The Traffic Signal - YouTube

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