Course Introduction and Two-Lane Highway Horizontal Alignment

1
Course Introduction and Two-Lane Highway
Horizontal Alignment

• Lecture 1 CE 578 Highway Traffic Operations

2
Course Topics

• Highway traffic operations
• Two-lane highway emphasis (40)
• Remainder on freeways (60)

3
Course Website

• Address www.webs1.uidaho.edu/ce578
• Organization
• Syllabus
• Schedule
• Assignments
• Course materials
• Evaluation

4
Course Website (cont.)

• Purpose course materials delivery
• Assignments
• Solutions
• Class reading
• Announcements
• Software files
• Class policy
• Exam schedule

5
Course Grading

• A90 90gtB 8080gtC 70 70gtD 60 60gtF
• Grade is based on
• Projects (20)
• Twelve mini-exams (60)
• Final exam (20)
• Assignments not graded

6
Horizontal Alignment

• Purpose Review primary design elements
• Objectives
• Design circular curve alignment
• Estimate design speed of circular curve

7
Circular Curve Alignment

• Labels and Terms
• Point of curvature (PC)
• Point of tangency (PT)
• Point of intersection (PI)
• Curve length (L)
• Curve Radius (R)
• External angle (?)
• Tangent (T)

8
Circular Curve Equations

• Tangent
• Curve length
• Station of PC and PT

9
Circular Curve Design Speed

• Side friction (fs)
• Curve radius (R)
• Gravity constant (g)?32.2 ft/sec2
• Superelevation (e)

10
Circular Curve Design Speed
Design Speed (mph) fs
15 0.175
20 0.170
25 0.165
30 0.160
35 0.155
40 0.150
45 0.145
50 0.140
55 0.130
60 0.120
65 0.110
70 0.100
75 0.090
80 0.080

• Maximum Side friction standard values (AASHTO
  Green Book (pp. 147)

11
Circular Curve Design Speed

• Superelevation?expressed as rise over run

A
1 ft
e
A
A
A
Plan View
Cross-Sectional View
12
Assignment

• Horizontal curve alignment (circular)
• Verify the following are correct for a given
  design on US 12 at curves with PC 24286.8 and PC
  28301.7, given the curve radius, curve PC, and
  external angle
• PI (not shown in plans),
• T,
• PT, and
• L.
• Estimate the design speed for the above curves,
  given the plan sheet superelevations and radius
  (note superelevation for the first curve is
  0.1/ft)