Print this page Reducing Collisions on Horizontal Curves
Vincent D. Reynolds, MBA, P.E.
Course Outline
This 6 hour course will cover the strategies that can be implemented to reduce collisions on horizontal curves. Several strategies will be studied such as superelevation enhancement, shoulder rumble strips, centerline rumble strips, roadway lighting and warning sign placement.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of course materials.
Learning Objective
At the conclusion of this course, the student would have learned the following:
- The number of fatal crashes at horizontal curves;
- Strategies to reduce the likelihood of a vehicle leaving the roadway at horizontal curves;
- Percentages of fatalities occurring on roadway curves;
- Types of roadways where fatalities occur most often;
- Percentage of fatal crashes on curved roadway segments;
- Strategies to reduce the likelihood of a vehicle leaving its land and either crossing the roadway centerline;
- The average range of departure angles for ROR crashes;
- The effects of post-mounted delineators on sharp curves;
- The importance of driver sight distance along horizontal curves;
- How to calculate the stopping sight distance;
- Approaches to enhance delineation at curves;
- King-pin-to-center-of-rear axle (KCRA) restrictions on California’s state highways;
- Various uses of shoulder rumble strips;
- Advantages and disadvantages of shoulder and centerline rumble strips;
- The primary function of centerline rumble strips;
- The effects of edge drop-offs;
- The role of tire friction to determine the margin of safety;
- Statistics for rollover fatalities for trucks on the U.S. highway system;
- How to improve a superelevation deficiency;
- How the accident modification factor (AMF) relates to superelevation deficiency;
- How to determine the accident modification factor (AMF);
- How spiral curves are used to make horizontal curves safer;
- How to define vehicle off-tracking; and
- Changes to a roadway that could make horizontal alignments safer.
Intended Audience and Benefit
This course is intended for Highway designers, city planners, municipal and public works engineers, traffic engineers, project managers, and any persons working in the civil engineering field or anyone with an interest increasing highway safety along horizontal curves.
Course Introduction
There are thousand of miles of the U.S. highway system that traverse the nation through mountains, valleys, deserts, forests, and over bodies of water. Roadway alignment would not be possible without the use of horizontal curves. Horizontal curves provide a smooth transition for vehicles traveling along the highway. Horizontal curves are designed so that the vehicles centrifugal force can be countered under normal circumstances. Horizontal curves can counter a vehicles centrifugal force by the use of tire friction aided with roadway superelevation.
Course Content
This course will cover the strategies that can be implemented to reduce collisions on horizontal curves. Several strategies will be studied such as superelevation enhancement, shoulder rumble strips, centerline rumble strips, roadway lighting and warning sign placement.
The student will be directed to study the document “A Guide for Reducing Collisions on Horizontal Curves,” as published on the website of the Transportation Research Board (TRB).
Reducing Collisions on Horizontal Curves
Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.
Course Summary
This course contains very useful knowledge can be utilized by the highway designer. Often times the designer needs a refresher to gain useful information that can make their designs safer and more efficient. This course contains information that can result in safer highway travel.
Using good engineering judgment is always paramount in any situation. Utilizing good judgment and the knowledge gained in this course will aid the reader with the knowledge to be a success in highway design, and specifically horizontal curves.
Related Links
For additional technical information related to this subject, please visit the following websites:
http://www.fhwa.dot.gov/
http://www.usace.army.mil/
http://www.dot.gov/new/index.htm
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
