Live support chatRoadway Horizontal Alignments
In Roadway Horizontal Alignments, you'll learn ...
- What is side friction factor and how to calculate it
- Methods for attaining superelevation in a spiral curve
- Cases where speed, curvature, or width may require appropriate traveled way widening
- How intersection sight distance varies according to the different types of traffic control
- Procedure for coordination of horizontal and vertical alignments
Overview
Preview a portion of this course before purchasing it.
Credit: 3 PDH
Length: 51 pages
The roadway horizontal alignment is a series of horizontal 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.
In today’s environment, designers must do more than merely apply design standards and criteria to ‘solve’ a problem. They must understand how various roadway elements contribute to safety and facility operation, including the horizontal alignment.
This course 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 horizontal alignments.
Learning Objectives
Upon completion of this course, participants will be able to:
- Describe horizontal alignment.
- Explain why design speed selection is a critical decision that should be made at the beginning of the planning and design process.
- Identify maximum superelevation rates and minimum curvature.
- Explain how grades affect superelevation rates.
- Describe locations where "tangent-to-curve" transitions are used.
- Identify the AASHTO equation for determining the minimum length of superelevation runoff.
- Explain how to locate a curve's superelevation runoff with respect to its Point of Curvature (PC).
- Describe when to use spiral curves.
- Identify the AASHTO formula for the minimum length of a spiral curve.
- Describe the maximum spiral radius.
- Explain the minimum and maximum spiral length.
- Identify the lengths of tangent runoff and superelevation runoff in a spiral curve.
- Describe the axis of rotation when a median is present.
- Explain two types of drainage problems for pavement surfaces in superelevation transition sections.
- Describe factors that impact the amount of widening on horizontal curves needed for offtracking.
- Explain the determination of stopping sight distance (SSD) and decision sight distance (DSD).
- Design values for passing sight distance on two-lane highways.
- Identify general controls for horizontal alignments.
Certificate of Completion
You will be able to immediately print a certificate of completion after passing a multiple-choice quiz consisting of 25 questions. PDH credits are not awarded until the course is completed and quiz is passed.
| This course is applicable to professional engineers in: | ||
| Alabama (P.E.) | Alaska (P.E.) | Arkansas (P.E.) |
| Delaware (P.E.) | District of Columbia (P.E.) | Florida (P.E. Area of Practice) |
| Georgia (P.E.) | Idaho (P.E.) | Illinois (P.E.) |
| Illinois (S.E.) | Indiana (P.E.) | Iowa (P.E.) |
| Kansas (P.E.) | Kentucky (P.E.) | Louisiana (P.E.) |
| Maine (P.E.) | Maryland (P.E.) | Michigan (P.E.) |
| Minnesota (P.E.) | Mississippi (P.E.) | Missouri (P.E.) |
| Montana (P.E.) | Nebraska (P.E.) | Nevada (P.E.) |
| New Hampshire (P.E.) | New Jersey (P.E.) | New Mexico (P.E.) |
| New York (P.E.) | North Carolina (P.E.) | North Dakota (P.E.) |
| Ohio (P.E. Self-Paced) | Oklahoma (P.E.) | Oregon (P.E.) |
| Pennsylvania (P.E.) | South Carolina (P.E.) | South Dakota (P.E.) |
| Tennessee (P.E.) | Texas (P.E.) | Utah (P.E.) |
| Vermont (P.E.) | Virginia (P.E.) | West Virginia (P.E.) |
| Wisconsin (P.E.) | Wyoming (P.E.) | |
Preview a portion of this course before purchasing it.
Credit: 3 PDH
Length: 51 pages
