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/ce578www.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 A≥90%; 90%>B ≥80%;80%>C ≥70%; 70%>D ≥60%; 60%>F 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 (Δ) –Tangent (T)

8. Circular Curve Equations Tangent Curve length Station of PC and PT

9. Circular Curve Design Speed Side friction (f s ) Curve radius (R) Gravity constant (g)  32.2 ft/sec 2 Superelevation (e)

10. Circular Curve Design Speed Maximum Side friction standard values (AASHTO Green Book (pp. 147) Design Speed (mph) fsfs 150.175 200.170 250.165 300.160 350.155 400.150 450.145 500.140 550.130 600.120 650.110 700.100 750.090 800.080

11. Circular Curve Design Speed Superelevation  expressed as rise over run Plan View Cross-Sectional View 1 ft e A A A A

12. Assignment Horizontal curve alignment (circular) –Verify the following are correct for a given design on US 12 at curves with PC 242+86.8 and PC 283+01.7, 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)