Roadway Horizontal Alignments I

The roadway horizontal alignment is a series of tangents (straight roadway sections), circular curves, and spiral transitions. It shows the proposed roadway location in relation to the existing terrain and adjacent land conditions. Together with the vertical alignment (grades and vertical curves) and roadway cross-sections (lanes, shoulders, curbs, medians, roadside slopes, ditches, sidewalks), the horizontal alignment (tangents and curves) helps to provide a three-dimensional roadway layout.

This course is the first of two that focuses on the geometric design of horizontal alignments for modern roads and highways. Its contents are intended to serve as guidance and not as an absolute standard or rule. Upon course completion, you should be familiar with the general design of horizontal roadway alignments. The course objective is to give engineers and designers an in-depth look at the principles to be considered when designing roadways.

A Policy on Geometric Design of Highways and Streets (also known as the “Green Book”) published by the American Association of State Highway and Transportation Officials (AASHTO) is considered to be the primary guidance for U.S. roadway design. For this course, Chapter 3 (Section 3.3 Horizontal Alignment) will be used exclusively for fundamental roadway geometric design principles.

Once you complete your course review, you need to take a multiple-choice quiz consisting of fifteen (15) questions to earn 3 PDH credits

Learning Objectives

This course is intended to provide you with the following specific knowledge and skills

Design Considerations

Cross slopes
Radii
Grades

Horizontal Curves

Side friction
Radii
Superelevation
Grades

Tangent-Curve Transitions

Runoff lengths
Locations

Spiral Curves

Lengths
Radii
Axis of rotation

Offtracking

Download the Course to review and begin earning your PDH credits.

We provide technical courses for PDH credits that meet Board requirements for Professional Engineers, Geologists and Land Surveyors. This courses is guaranteed to be accepted in AK, AL, AR, FL, GA, IA, IL, ID, IN, KS, KY, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, SC, SD, TN, TX, UT, VA, VT, WI, WV, and WY. Before purchasing this course, please confirm that your state Board is listed above.