Highway Capacity Manual (HCM), Transportation Research Board, Washington, D.C., 2000, ISBN 0-309-06681-6.
Design Manual M 22-01.06, (WSDOT) Washington State Department of Transportation, December 2009.
Design Manual for Roads and Bridges (DMRB), The Highways Agency, The Scottish Office Development Department, The Welsh Office Y SWYDDFA GYMREIG, The Department of Environment for Northern Ireland, February 2008.
Highway Design Manual, California Transport Department.