M22-01. 20 Design Manual
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- Exhibit 1360-4 Ramp Design Speed Main Line Design Speed (mph) 50 55 60 65 70 80
| Chapter 1360
Interchanges WSDOT Design Manual M 22-01.20 Page 1360-7 September 2021 1360.03 Ramps 1360.03(1) Ramp Design Speed The design speed for a ramp is based on the design speed for the freeway main line. It is desirable that the ramp design speed at the connection to the freeway be equal to the free-flow speed of the freeway. Meet or exceed the upper range values from Exhibit 1360-4 for the design speed at the ramp connection to the freeway. Transition the ramp design speed to provide a smooth acceleration or deceleration between the speeds at the ends of the ramp. However, do not reduce the ramp design speed below the lower- range speed of 25 mph. For loop ramps, use a design speed as high as feasible, but not lower than 25 mph. These design speed guidelines do not apply to the ramp in the area of the ramp terminal at-grade intersection. In the area of the intersection, use a design speed of 15 mph for turning traffic or 0 mph for a stop condition. Use the allowed skew at the ramp terminal at-grade intersection to minimize ramp curvature. For freeway-to-freeway ramps and C-D roads, the design speed at the connections to both freeways is the upper range values from Exhibit 1360-4; however, with justification, the midrange values from Exhibit 1360-4 may be used for the remainder of the ramp. When the design speed for the two freeways is different, use the higher design speed. Existing ramps meet design speed criteria if acceleration or deceleration criteria are met (see Exhibit 1360-10 or Exhibit 1360-11) and superelevation meets the criteria in Chapter 1250. Exhibit 1360-4 Ramp Design Speed Main Line Design Speed (mph) 50 55 60 65 70 80 Ramp Design Speed (mph) Upper Range 45 50 50 55 60 70 Midrange 30 40 45 45 50 60 Lower Range 25 25 25 25 25 25 tải về 1.86 Mb. Chia sẻ với bạn bè của bạn:
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