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Wisconsin DOT Facilities Development Manual (FDM) Weston Philips 1/27/05.

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Presentation on theme: "Wisconsin DOT Facilities Development Manual (FDM) Weston Philips 1/27/05."— Presentation transcript:

1 Wisconsin DOT Facilities Development Manual (FDM) http://www.dot.ca.gov/dist1/d1traffic/cap/curve.jpg Weston Philips 1/27/05

2  Superelevation  Vertical Alignment

3 Superelevation

4 Ch. 3 Elements of Design In Horizontal Alignment Section p. 173 Ch. 2 Alignments Section 2A-2, 2A-3 A different angle on superelevation?

5 Axis of Rotation 1.Rotate pavement about centerline 2.Rotate about inner edge of pavement 3.Rotate about outside edge of pavement 4.Rotate about center of median (Divided)

6 Axis of Rotation

7

8 Superelevation Profile Two-Lane Highway – Centerline Rotation

9 Normal Crown

10 Tangent Runout/Crown Runoff Horizontal

11 Superelevation Runoff Superelevation = Cross Slope

12 Superelevation Achieved

13

14 Max Superelevation Rate Nomograph (Discussed Later)

15 Max Superelevation Rate Cont’d

16 How to Calculate Superelevation 1. Using Superelevation Tables 2. Nomographs 3. Simple Curve Formula

17 Superelevation Option 1 ► ► First solution is obtained from the superelevation tables, emax = 0.04 (Figure 9) ► ► R = 700.; e = 0.039 Given: VD = 40 mph R = 700 ft. fmax = 0.178 (from Table 7) 3.9% Note: Choose Table emax = 0.04

18 Iowa has ramp tables.

19

20 Minimum Radius ► Greenbook p. 145 (186 pdf)  Minimum Radius Table

21 Superelevation Option 2 Radius 40mph 700 feet e = -2.5%

22 Note: Greenbook contains derivation of equations/graphs.

23 Superelevation Option 3 Third solution is obtained from the simplified curve formula: e = (VD 2 /15R) - f max (English version) e = (40 2 /15*700) - 0.178 = 0.152 - 0.178 = -0.0256 -2.56% Where: VD = design speed R = radius e = superelevation rate f max = maximum side friction. Note: Metric Version e = (VD 2 /127R) - f max (metric version).

24 Superelevation Transition ► ► Superelevation transition is the length required to rotate the cross slope of a highway from a normal crowned slope to a fully superelevated cross slope.

25 Transition Placement ► ► WisDOT practice is to place the tangent runout and approximately two-thirds of the length of runoff on the tangent approach and one-third of the length of runoff on the curve.

26 Calculations Given: PC = Station 870+00.00 L = 115 ft. (Table 7, 40mph design speed) X = L * NC/ e = 115 *.02/.02 = 115ft Theoretical point of normal crown PC - 2/3L - X = 870+00.00 - 76.67 - 115 = Station 868+08.33 Theoretical point of full superelevation PC + 1/3L = 870+00.00 + 38.33 = Station 870+38.33 ► Compute the theoretical point of normal crown and the theoretical point of full superelevation. Where: PC = Point of Curvature L = Length of Runoff X = Length of Tangent Runout NC = Normal Crown of 2%

27 Length of Runoff (L)

28 The adjustment factor (α) is used to adjust for different roadway widths. Length of Runoff (L)

29

30 ► Greenbook p. 171 (pdf 212) Length of Runoff (L)

31 Tangent Runout L t or X

32

33

34

35 http://www.scvresources.com/highways/sr_23.htm Vertical Alignment

36 ► ► The highway vertical alignment consists of tangents or grades and vertical curves. ► ► Design vertical curves to provide adequate sight distance, safety, comfortable driving, good drainage, and pleasing appearance. http://listproc.ucdavis.edu/archives/cbximages/log0306/att-0011/01-CoolRide.jpg

37 No Vertical Curves? “Some rounding of the deflection point is anticipated during construction.” “Although grade changes without a vertical curve are discouraged, there may be situations where it is necessary.”

38 Max % Grade By Functional Class

39 Vertical Curves Vertical curves are generally identified by their K values. K is the rate of curvature and is defined as the length of the vertical curve divided by the algebraic difference in grade Note: For Drainage, use K > 167 K

40 Question: Is there more on Vertical Alignment in the Wisconsin Manual? 2A-1 p. 235 (276 pdf)


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