AASHTO DS-6 pdf free download

AASHTO DS-6 pdf free download.A Policy on Design Standards- Interstate System.
TraveLed Way and ShouLder Cross SLope
On tangent sections, the rate of cross slope applicable to the traveled way is influenced by drainage
needs. The normal cross slope of the traveled way is 2.0 percent and shall not be Less than 1.5 percent.
When three or more lanes are inclined in the same direction, or in areas of intense rainfall, refer to
AASHTO’s Green Book for additional guidance. Paved shoulders should have a cross slope in the range of
2.0 to 6.0 percent but shall not have a cross slope less than the cross slope of the adjacent traveled way.
The cross slope break between the traveled way and the shoulder on the high side of superelevated curves should not exceed 8 percent.
Medians
Medians in rural areas in level or rolling topography should be at least 50 ft (15 m), and preferably 60 ft (18 rn), wide. Medians in urban or mountainous areas shalL be wide enough to accommodate the left shoulder width pLus the space needed for a barrier. Wider medians may be needed for drainage and may provide flexibility to accommodate future widening for additional travel lanes. Refer to the current edition of AASHTO’s Roadside Design Guide for guidance on barrier installation in the median.
Median areas should not be drained across travel lanes. Refer to the AASHTO Drainage Manual, Volume 1— Policy for more information.
Roadside Design
The clear zone provided should be determined through appLication of the procedures in the AASHTO Roadside Design Guide. Objects that cannot be made to be breakaway or yielding, such as walls, piers, and abutments, should be shielded by instalLation of crashworthy barriers or attenuators.
Depressed Interstates in urban areas have more restrictive rights-of-way which may need retaining walLs or bridge piers to be placed within the clear zone. Such waLls and piers should be at [east 2 ft (0.6 m) beyond the outer edge of shoulder. Retaining walls and pier crash walls should incorporate an integral concrete barrier shape, or they should be offset from the shoulder a sufficient distance to permit shieLding with a separate barrier.
Sidestopes
Sideslopes within the clear zone are typically 1V:6H or flatter and should not be steeper than 1V:4H. Where sLopes steeper than 1V:4H are used within the clear zone, refer to the current edition of AASHTO’s Roadside Design Guide for guidance.
Curbs
Caution should be exercised in the use of curbs on Interstates. Where curbs are provided, they shall not be closer to the traveled way than the outer edge of the paved shoulder, shall have a sLoping face, and be limited to a height of 4 in. (100 mm). SpeciaL care should be taken when curbs are pLaced next to barriers. For more information, refer to the discussion on curb types and their placement in AASHTO’s Green Book.
Muttimodat Accommodations
In urban and suburban areas, consideration should be given to providing bicycle and pedestrian accommodation along the crossroad or reserving sufficient space for such facilities to be added in the future. Refer to AASHTO’s Guide for the Development of Bicycle Facilities and the AASHTO Guide for the Planning, Design, and Operation of Pedestrian Facilities for more information regarding bicycle and pedestrian accommodation. On planned or existing transit corridors, transit should also be accommodated through the interchange. Refer to AASHTO’s Guide for Geometric Design of Transit Facilities on Highways and Streets for more information regarding transit accommodation.
INTERCHANGES
Interchanges shall be provided between all intersecting Interstate routes, between other selected access-controlled highways, and at other selected public highways to facilitate the distribution of traffic. Each interchange shall provide for all traffic movements.AASHTO DS-6 pdf download.