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Sometimes concrete bridges are grooved by machine. Bridge decks freeze before roads do because the cold hits both the top and the bottom of a bridge.

The grooves increase traction and help prevent sliding when it's snowy or icy.

Grooves also lessen the likelihood of hydro-planing.

Anyway, the high-pitched noise is caused by the grooves in vehicles tires vibrating against the grooves in the concrete deck.

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14y ago

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