1 / 11

Geometric Design of Highways

Geometric Design of Highways. Highway Alignment is a three-dimensional problem Design & Construction would be difficult in 3-D so highway alignment is split into two 2-D problems. Components of Highway Design. Plan View. Horizontal Alignment. Vertical Alignment. Profile View.

Download Presentation

Geometric Design of Highways

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. Geometric Design of Highways • Highway Alignment is a three-dimensional problem • Design & Construction would be difficult in 3-D so highway alignment is split into two 2-D problems

  2. Components of Highway Design Plan View Horizontal Alignment Vertical Alignment Profile View

  3. Horizontal Alignment Today’s Class: • Components of the horizontal alignment • Properties of a simple circular curve

  4. Horizontal Alignment Tangents Curves

  5. Tangents & Curves Tangent Curve Tangent to Circular Curve Tangent to Spiral Curve to Circular Curve

  6. Layout of a Simple Horizontal Curve R = Radius of Circular Curve BC = Beginning of Curve (or PC = Point of Curvature) EC = End of Curve (or PT = Point of Tangency) PI = Point of Intersection T = Tangent Length (T = PI – BC = EC - PI) L = Length of Curvature (L = EC – BC) M = Middle Ordinate E = External Distance C = Chord Length Δ = Deflection Angle

  7. Circular Curve Components

  8. Properties of Circular Curves Degree of Curvature • Traditionally, the “steepness” of the curvature is defined by either the radius (R) or the degree of curvature (D) • Degree of curvature = angle subtended by an arc of length 100 feet R = 5730 / D (Degree of curvature is not used with metric units because D is defined in terms of feet.)

  9. Properties of Circular Curves Length of Curve • For a given external angle (Δ), the length of curve (L) is directly related to the radius (R) L = (RΔπ) / 180 = RΔ / 57.3 • In other words, the longer the curve, the larger the radius of curvature R = Radius of Circular Curve L = Length of Curvature Δ = Deflection Angle

  10. Properties of Circular Curves Other Formulas… Tangent: T = R tan(Δ/2) Chord: C = 2R sin(Δ/2) Mid Ordinate: M = R – R cos(Δ/2) External Distance: E = R sec(Δ/2) - R

  11. Circular Curve Geometry

More Related