Design speed

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The design speed is a tool used to determine geometric features of a new road or street during road design. Contrary to the word's implication, the design speed of the road or street is not necessarily its vehicle speed limit or maximum safe speed; that can be higher or lower.

Choosing a design speed means finding a balance between several interests which compete for priority,^[1] such as high vehicle speeds to allow drivers to travel to their destinations quickly versus low vehicle speeds for the safety of people outside the vehicle (such as pedestrians and cyclists),^[2] or quick movement of peak traffic (traffic engineering) versus maximising the economic development potential of the street (urban planning).^[3]