Intersection Geometric Design

In Intersection Geometric Design, you'll learn ...

• Variables for the type of intersection to be used at a location
• General design guidelines regarding horizontal and vertical alignment combinations
• Recommended sight triangle dimensions for different types of traffic control
• Left turn lane design guidelines
• Basic single lane and multilane roundabout design principles

Overview

Preview a portion of this course before purchasing it.

Credit: 3 PDH

Length: 48 pages

This course summarizes and highlights the geometric design process for modern roadway intersections. The contents of this course are intended to serve as guidance and not as an absolute standard or rule.

When you complete this course, you should be familiar with the general guidelines for at-grade intersection design. The course objective is to give engineers and designers an in-depth look at the principles to be considered when selecting and designing intersections.

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 9 - Intersections will be used exclusively for fundamental roadway geometric design principles.

Intersections are unique roadway elements where conflicting vehicle streams (and sometimes non-motorized users) share the same space. This area encompasses all modes of travel (pedestrian, bicycle, passenger vehicle, truck, and transit) as well as auxiliary lanes, medians, islands, sidewalks and pedestrian ramps. These may further heighten the accident potential and constrain the operational efficiency and network capacity of the urban street system. However, the main objective of intersection design is to facilitate the roadway user and enhance efficient vehicle movement.

Learning Objectives

Upon completion of this course, participants will be able to:

• Identify basic elements of intersection design.
• Describe types of intersections.
• Explain why the horizontal and vertical geometries are the most critical design elements of any roadway.
• Summarize the design guidelines for intersection sight distance.
• Describe the design of turning roadways based on various design vehicles.
• Explain principles of channelization.
• Identify the purposes of islands and the minimum curbed corner island area.
• Explain auxiliary lane design guidance.
• Describe length requirements for deceleration lanes.
• Explain control radii for median openings.
• Describe indirect left turns and U-turns.
• Explain the purpose, benefits, and preferred sites for jughandles.
• Describe basic principles for modern roundabouts.
• Explain roundabout geometric elements and speed management.
• Identify appropriate lane arrangements and path alignment for roundabouts.
• Describe roundabout design considerations for pedestrians and bicycles.
• Identify frontage road design considerations.
• Describe elements of pedestrian facilities.
• Identify types of curb ramps.
• Describe factors to consider for accommodating bicycles.
• Identify horizontal alignment guidelines for railroad-highway grade crossings.

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.