1 / 22

Islamic University of Gaza Civil Engineering Department Surveying II ECIV 2332 By B elal A lmassri

Islamic University of Gaza Civil Engineering Department Surveying II ECIV 2332 By B elal A lmassri. Chapter 9 Route Surveying – Part 5. Transition Curve Layout Using The Theodolite. Preliminary work and calculations. Setting out the curves. The whole procedure. Example 9.4 .

gaia
Download Presentation

Islamic University of Gaza Civil Engineering Department Surveying II ECIV 2332 By B elal A lmassri

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Islamic University of GazaCivil Engineering DepartmentSurveying IIECIV 2332ByBelalAlmassri

  2. Chapter 9 Route Surveying – Part 5 Transition Curve Layout Using The Theodolite. Preliminary work and calculations. Setting out the curves. The whole procedure. Example 9.4 .

  3. Transition Curve Layout Using The Theodolite: • In order to lay out a combination of circular curve and transition curve, the following procedure is used: • Preliminary work and calculations. • Transition Curve. • Circular Curve. • Setting out the curve. • Left transition curve. • Right transition curve. • Circular curve. • Common tangent between transition and circular curves.

  4. Transition Curve Equations • Length of transition curve (L): - Past experience or uniform rate or equation • a: Rate of change of radial acceleration in m/sec^3 (0.3 – 0.5). • R: Circular curve radius. • V: Design speed in m/sec.

  5. Transition curve shift (S): • The amount of distance that the circular curve is shifted inward to be adopted with the transition curve. • L: Length of transition curve. • R: Circular curve radius.

  6. The total length of the tangent Ts or P-T line: • The total length from the point of the intersection PI to the start point of the transition T can be computed through the following formula: • L: Length of transition curve. • S: Shift of transition curve. • R: Radius of circular curve. • Δ: Central Angle.

  7. Chainage of TS ( Tͦ ) and SC ( T1): Chainage of Tͦ = Chainage of PI - P Tͦ Chainage of T1 = Chainage of Tͦ + L • Lengths of partial chords for the left transition curves: • C ≤ R/40 • C1 to be as computed in circular curves. • C2 = L – (C1+ nC), n: intermediate chords.

  8. Deflection angles of the transition curve: • Angle of T1 (the spiral angle): • Deflection angle of transition curve: • CHECK! .....Sum of di =

  9. Underground . . .

  10. The Whole Calculations Procedure: • Find R and Δ of the circular curve. • Find L, S and PTͦ of the transition curve. • Find Chainage of Tͦ , T1, T2 and T3. • Find the Partial chords and the deflection angles for the following: • Right transition curve. • Circular Curve. • Left Transition Curve.

  11. Example 9.4

  12. Vertical Curves • Def: A parabolic curve that is applied to make a smooth and safe transition between two grades on a roadway or a highway. VPC: Vertical Point of Curvature VPI: Vertical Point of Intersection VPT: Vertical Point of Tangency G1, G2: Tangent grades in percent A: Algebraic difference in grades L: Length of vertical curve VPI VPT VPC

  13. There are two kinds of vertical curve: • SummetVertical Curves: Type I and Type II. • Sag Vertical Curves : Type III and Type IV.

  14. Information needed for vertical curves design: • Gradients g1 and g2. • Chainage and elevation of VPI. • Length of the curve L. • Sight Distance: The length of the roadway visible to driver. • Stopping sight distance. (S.S.D) • Passing sight distance. (P.S.D)

  15. Stopping Sight Distance (SSD) is the viewable distance required for a driver to see so that he or she can make a complete stop in the event of an unforeseen hazard.

  16. V: Velocity in m/s t: Perception and reaction time (2.5 sec) f: coefficient of friction for roads i: gradient (Up is +ve, Down is –ve) g: gravity (9.81m/s^2)

  17. Passing Sight Distance (PSD) is the clear distance that the driver must view in order to be able safely pass the car in front of him. (PSD=2. SSD)

  18. Vertical Curve Calculations • Location of Max/Min elevation on the curve: • Elevation of any point on the curve:

  19. Chainage and elevation of VPC and VPT:

  20. Length of Vertical Curve: Method 1: K: Rate of curvature. (By Tables) A: Difference of gradients. Method 2: depends on the sight distance, gradient difference: Equations (9.46, 9.47, 9.48, 9.50) from the text book.

  21. Example 9.7

More Related