What does an eight-sided red sign mean?
AnswerStop
The octagon shape is reserved for stop signs.
Vehicles · Facts & stats
Traffic facts & stats
7 fact-checked facts about road traffic, signals, signs and how traffic flows, each with the reason behind it. 5 more are in today's round and join this page after it closes.
The basics
What shape is a US yield sign?
AnswerA downward-pointing triangle
The yield sign is an inverted triangle.
Going deeper
The first traffic signal, a gas-lit one from 1868, stood near which building?
AnswerLondon's Houses of Parliament
It was installed at Westminster in 1868 to control horse-drawn traffic.
Garrett Morgan received a 1923 patent for what?
AnswerA three-position traffic signal
Morgan's signal added a warning position between stop and go.
In the US, what does a round yellow warning sign usually mean?
AnswerRailroad crossing ahead
The circular yellow sign is the advance warning for a rail crossing.
Expert level
What is the idea that adding road capacity leads to more driving called?
AnswerInduced demand
New lanes can attract extra trips, so congestion often returns.
In the US, what does a five-sided (pentagon) sign indicate?
AnswerA school zone or school crossing
The pentagon shape is used for school zone and school crossing signs.
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