Design speed

From Wikipedia, the free encyclopedia

The design speed of a road is the maximum speed at which a motor vehicle can be operated safely on that road in perfect conditions.

The precise definition, according to the AASHTO Green Book,^[1] is "the maximum safe speed that can be maintained over a specified section of highway when conditions are so favorable that the design features of the highway govern. The assumed design speed should be a logical one with respect to the topography, the adjacent land use, and the functional classification of highway." A majority of US states use this definition.^[2]

[edit] Factors

There are a number of factors involved in determining the design speed of a particular road, including its functional classification, its geometric design, the actual operating speed of the road, the maximum speed limit permissible by law, and the traffic volume of the road.

[edit] See also

• Operating speed
• Speed limit

[edit] References

1. ^ A Policy on Geometric Design of Highways and Streets: 1994. American Association of State Highway and Transportation Officials. ISBN 978-1560510684. 
2. ^ Design Speed, Operating Speed, and Posted Speed Practices (Report 504) (PDF). National Cooperative Highway Research Program.