M22-01. 20 Design Manual
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- Exhibit 1360-2 Interchange Spacing
| Chapter 1360
Interchanges WSDOT Design Manual M 22-01.20 Page 1360-5 September 2021 1360.02(3) Spacing To avoid excessive interruption of main line traffic, consider each proposed facility in conjunction with adjacent interchanges, intersections, and other points of access along the route as a whole. The minimum spacing between adjacent interchanges is 1 mile in urban areas, 3 miles on the Interstate in rural areas, and 2 miles on non-Interstate in rural areas (see Exhibit 1360-2). In urban areas, spacing less than 1 mile may be used with C-D roads or grade-separated (braided) ramps. Interchange spacing is measured along the freeway centerline between the centerlines of the crossroads. The spacing between interchanges may also be dependent on the spacing between ramp connections. The minimum spacing between the gore noses of adjacent ramps is given in Exhibit 1360-3. Exhibit 1360-2 Interchange Spacing Gore nose Interchange spacing: 1 mi min Urban 2 mi min Rural [2] Ramp connection spacing [1] Notes: [1] As a minimum, provide length for weaving and signing, but not less than given in Exhibit 1360-3. [2] 3 miles on the Interstate System. Consider either frontage roads or C-D roads to facilitate the operation of near-capacity volumes between closely spaced interchanges or ramp terminals. C-D roads may be needed where cloverleaf loop ramps are involved or where a series of interchange ramps have overlapping speed change lanes. Base the distance between successive ramp terminals on capacity. Check the intervening sections by weaving analyses to determine whether capacity, sight distance, and effective signing can be provided without the use of auxiliary lanes or C-D roads. Provide justifications for existing interchanges with less-than-desirable spacing or ramp connection spacing to remain in place. tải về 1.86 Mb. Chia sẻ với bạn bè của bạn:
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