Procedures for Setting Advisory Speeds on Curves

Program Contact

Guan Xu
Guan.Xu@dot.gov
(202) 366-5892

FHWA treskelion logo.
U.S. Department of Transportation
Federal Highway Administration

June 2011

FHWA-SA-11-22

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Curve Advisory Software (CAS)
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Disclaimer The contents of this handbook reflect the views of the authors, who are responsible for the facts and the accuracy of the data published herein. The contents do not necessarily reflect the official view or policies of the Federal Highway Administration (FHWA). This handbook does not constitute a standard, specification, or regulation. It is not intended for construction, bidding, or permit purposes. The engineer in charge of the project was Robert Milstead, P.E. #17172 (Maryland). Notice The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein solely because they are considered essential to the object of this handbook. Acknowledgements The report that led to the development of this handbook was sponsored by the Texas Department of Transportation and the Federal Highway Administration. The research report was written by Dr. James Bonneson, Mr. Michael Pratt, Mr. Jeff Miles, and Dr. Paul Carlson (1). These researchers are employees with the Texas Transportation Institute (TTI).

Disclaimer

The contents of this handbook reflect the views of the authors, who are responsible for the facts and the accuracy of the data published herein. The contents do not necessarily reflect the official view or policies of the Federal Highway Administration (FHWA). This handbook does not constitute a standard, specification, or regulation. It is not intended for construction, bidding, or permit purposes. The engineer in charge of the project was Robert Milstead, P.E. #17172 (Maryland).

Notice

The United States Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein solely because they are considered essential to the object of this handbook.

Acknowledgements

The report that led to the development of this handbook was sponsored by the Texas Department of Transportation and the Federal Highway Administration. The research report was written by Dr. James Bonneson, Mr. Michael Pratt, Mr. Jeff Miles, and Dr. Paul Carlson (1). These researchers are employees with the Texas Transportation Institute (TTI).

Technical Report Documentation Page
Chapter 1. Introduction
	1.1 Overview
	1.2 Purpose And Scope
Chapter 2. Conveying Changes In Horizontal Alignment
	2.1 Overview
	2.2 Horizontal Curve Safety And Operation
	2.3 Warning Signs For Changes In Horizontal Alignment
	2.4 Curve Advisory Speed Software
Chapter 3. Methods For Establishing Advisory Speed
	3.1 Overview
	3.2 Direct Method
	3.3 Compass Method
	3.4 GPS Method
	3.5 Design Method
	3.6 Ball-Bank Indicator Method
	3.7 Accelerometer Method
	3.8 Confirming Speed For Conditions
	3.9 Workshops And Webinars
	3.10 Summary
Chapter 4. Curve Signing Guidelines
	4.1 Overview
	4.2 Guidelines
References

List of Tables

Table 1. Comparison of the Six Methods for Establishing Curve Advisory Speeds

Table 1. Comparison of the Six Methods for Establishing Curve Advisory Speeds

List of Figures

Figure 1 – Effect of Radius, Tangent Speed, and Vehicle Type on Curve Speed
Figure 2 – Curve Crash Rate as a Function of Radius
Figure 3 – Horizontal Alignment Signs and Plaques (MUTCD 2009 Edition)
Figure 4 – Curve Advisory Speed (CAS) Software Analysis Worksheet
Figure 5 – Location of Critical Portion of Curve
Figure 6 – Curve Advisory Speed (CAS) Software Input Data
Figure 7 – Curve Advisory Speed (CAS) Software Advisory Speed Calculation
Figure 8 – Effect of Lateral Shift on Travel Path Radius
Figure 9 – GPS Method Equipment Setup in Test Vehicle
Figure 10 – Texas Roadway Analysis and Measurement Software (TRAMS) Main Panel
Figure 11 – Import TRAMS Data
Figure 12 – Ball-Bank Indicator
Figure 13 – CurveRite Front Panel
Figure 14 – CurveRite Measurement
Figure 15 – MUTCD 2009 Edition Criteria for the Selection of Horizontal Alignment Sign
Figure 16 – MUTCD 2009 Edition Criteria for the Typical Spacing of Chevron Alignment Signs on Horizontal Curves
Figure 17 – MUTCD 2009 Edition Criteria for Advance Placement of Warning Signs
Figure 18 – Curve Advisory Speed (CAS) Software Traffic Control Device Guidance

Figure 1 – Effect of Radius, Tangent Speed, and Vehicle Type on Curve Speed

Figure 2 – Curve Crash Rate as a Function of Radius

Figure 3 – Horizontal Alignment Signs and Plaques (MUTCD 2009 Edition)

Figure 4 – Curve Advisory Speed (CAS) Software Analysis Worksheet

Figure 5 – Location of Critical Portion of Curve

Figure 6 – Curve Advisory Speed (CAS) Software Input Data

Figure 7 – Curve Advisory Speed (CAS) Software Advisory Speed Calculation

Figure 8 – Effect of Lateral Shift on Travel Path Radius

Figure 9 – GPS Method Equipment Setup in Test Vehicle

Figure 10 – Texas Roadway Analysis and Measurement Software (TRAMS) Main Panel

Figure 11 – Import TRAMS Data

Figure 12 – Ball-Bank Indicator