The cross slope of both the left and right shoulders should be between 2% and 6%, but not less than the main lanes.
Pavement sloping: On straight sections of the highway, the roadway is to have a cross slope of at least 1.5%, and preferably 2% to ensure proper drainage, with up to 2.5% in areas of heavy rainfall. In places with higher truck traffic, over 250 Directional Design Hour Volume, wider shoulders should be considered. In mountainous terrain, a left shoulder of 4 feet (1.2 m) and a right shoulder of 8 feet (2.4 m) are acceptable, except where there are at least four lanes in each direction, in which case both shoulders are to be at least 8 feet (2.4 m) wide. With three or more lanes in each direction, both shoulders are to be at least 10 feet (3.0 m) wide. Shoulder width: The minimum width of the left paved shoulder is 4 feet (1.2 m), and of the right paved shoulder 10 feet (3.0 m). Minimum lane width: The minimum lane width is 12 feet (3.7 m), identical to most US and state highways. Climbing lanes and emergency escape ramps should be provided where appropriate. Minimum number of lanes: There are to be at least two lanes in each direction, unless more are necessary for an acceptable level of service, according to the current edition of AASHTO's A Policy on Geometric Design of Highways and Streets. 
An additional 1% is allowed in urban areas.
Maximum grade: The maximum permissible vertical angle, or grade, along the highway is determined from terrain and design speed, with up to 6% generally allowed in mountainous areas, 5% in rolling terrain, and 4% on level terrain.The sight distance, curvature and superelevation of the highway should follow the current edition of AASHTO's A Policy on Geometric Design of Highways and Streets for the chosen design speed.Minimum design speed: A minimum design speed of 70 mph (113 km/h) is to be used, except in mountainous and urban areas, where the minimum is 50 mph (80 km/h).In urban and suburban areas, consideration should be given to accommodating bicycles and pedestrians along crossroads.
In urban areas, there should be no driveways or other access points to adjacent properties along the crossroad for at least 100 feet (30 m) from entrance and exit ramps, in both directions, and for at least 300 feet (91 m) in rural areas. Interchanges should be spaced at least 1 mi (1.6 km) apart in urban areas and 3 mi (4.8 km) apart in rural areas collector/distributor roads or other roadway configurations that reduce weaving can be used in urban areas to shorten this distance. Interchanges are to provide access to and from both directions of the highway and both directions of the crossroad. Controlled access: All access onto and off the highway is to be controlled with interchanges and grade separations, including all railroad crossings. 
Side clearances were reduced from the recommended 44.0 ft (13.4 m) to 38.0 ft (11.6 m) due to cost concerns. The Bobby Hopper Tunnel on I-49 in Arkansas was built with a 25 ft (7.6 m) height total clearance, leaving plenty of room for lighting and signs hanging from the ceiling and still exceeding the 16 ft (4.9 m) minimum for rural highways.
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