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| REPORT |
| This report is an archived publication and may contain dated technical, contact, and link information |
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| Publication Number: FHWA-HRT-13-077 Date: January 2014 |
Publication Number: FHWA-HRT-13-077 Date: January 2014 |
HTML Version of Errata for FHWA-HRT-13-077
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The following changes were made to the document after publication:
| Location | Corrected Values | URL |
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| Page i, Block 21 | 68 | /publications/research/safety/13077/index.cfm#errata01 |
| Page 4, SAFETY EFFECTS OF HORIZONTAL ALIGNMENT, Paragraph 1, Sentence 1, Line 2 | shown in figure 2 | /publications/research/safety/13077/002.cfm#errata02 |
| Page 4, SAFETY EFFECTS OF HORIZONTAL ALIGNMENT, Paragraph 1, Sentence 1, Figure 2 | N = [1.55 (LC)(V) + 0.014(D)(V) − 0.012(S)(V)](0.978)W − 30 | /publications/research/safety/13077/002.cfm#errata03 |
| Page 5, Paragraph 3, Sentence 2 | shown in figure 3: | /publications/research/safety/13077/002.cfm#errata04 |
| Page 5, Paragraph 6, Sentence 1 | as shown in figure 4: | /publications/research/safety/13077/002.cfm#errata05 |
| Page 8, Paragraph 1, Sentence 10 | [A = abs(G1 – G2 )] | /publications/research/safety/13077/003.cfm#errata06 |
| Page 9, DESCRIPTIVE STATISTICS, Paragraph 1, Sentence 1 | [million vehicle miles traveled in the 6-year period (MVMT)] | /publications/research/safety/13077/003.cfm#errata07 |
| Page 14, Paragraph 2, Bullet 2 | [this is a standard analysis of variance (ANOVA) using an NB distribution and a log link] | /publications/research/safety/13077/004.cfm#errata08 |
| Page 16, Paragraph 2, Sentence 1 | shown in figure 6 and figure 7 | /publications/research/safety/13077/004.cfm#errata09 |
| Page 16, Paragraph 4, Bullet 1,Sentence 2 | shown in figure 8 | /publications/research/safety/13077/004.cfm#errata10 |
| Page 17, Horizontal Curves and Tangents on Straight Grades, Paragraph 1,Sentence 1, Bullet 1 | [number of roadway segments (N) = 8,095 and total roadway length = 595 mi] | /publications/research/safety/13077/004.cfm#errata11 |
| Page 17, Horizontal Curves and Tangents on Straight Grades, Paragraph1, Sentence 1 | (i.e., number of roadway sections; total roadway length; and minimum, maximum, mean, and median values for specific parameters) | /publications/research/safety/13077/004.cfm#errata12 |
| Page 18, Paragraph 1, Sentence 1 | shown in figure 10 and figure 11 | /publications/research/safety/13077/004.cfm#errata13 |
| Page 20, Paragraph 5, Sentence 1 | shown in figure 12, figure 13, and figure 14 | /publications/research/safety/13077/004.cfm#errata14 |
| Page 23, Paragraph 1, Sentence 1 | shown in figure 16 and figure 17 | /publications/research/safety/13077/004.cfm#errata15 |
| Page 25, Paragraph 2, Sentence 1 | shown in figure 18 and figure 19 | /publications/research/safety/13077/004.cfm#errata16 |
| Page 26, Paragraph 1, Sentence 2 | shown in figure 20 and figure 21 | /publications/research/safety/13077/004.cfm#errata17 |
| Page 28, Paragraph 1, Sentence 1 | shown in figure 23 and figure 24 | /publications/research/safety/13077/004.cfm#errata18 |
| Page 29, Paragraph 5, Sentence 1 | shown in figure 25 and figure 26 | /publications/research/safety/13077/004.cfm#errata19 |
| Page 30, Paragraph 2, Sentence 3 | shown in figure 27 and figure 28 | /publications/research/safety/13077/004.cfm#errata20 |
| Page 32, Paragraph 1, Sentence 1 | shown in figure 30 and figure 31 | /publications/research/safety/13077/004.cfm#errata21 |
| Page 33, Paragraph 4, Sentence 1 | shown in figure 32 and figure 33 | /publications/research/safety/13077/004.cfm#errata22 |
| Page 36, Paragraph 1, Sentence 1 | shown in figure 35 and figure 36 | /publications/research/safety/13077/004.cfm#errata23 |
| Page 37, Paragraph 4, Sentence 1 | shown in figure 37 and figure 38 | /publications/research/safety/13077/004.cfm#errata24 |
| Page 39, HORIZONTAL CURVES AND TANGENTS ON STRAIGHT GRADES, Paragraph 1, Sentence 1 | shown in figure 39 and figure 40 | /publications/research/safety/13077/005.cfm#errata25 |
| Page 42, HORIZONTAL CURVES AND TANGENTS AT TYPE 1 CREST VERTICAL CURVES, Paragraph 1, Sentence 1 | shown in figure 43 and figure 44 | /publications/research/safety/13077/005.cfm#errata26 |
| Page 44, HORIZONTAL CURVES AND TANGENTS AT TYPE 1 SAG VERTICAL CURVES, Paragraph 1, Sentence 1 | shown in figure 47 and figure 48 | /publications/research/safety/13077/005.cfm#errata27 |
| Page 46, HORIZONTAL CURVES AND TANGENTS AT TYPE 2 CREST VERTICAL CURVES, Paragraph 1, Sentence 1 | shown in figure 51 and figure 52 | /publications/research/safety/13077/005.cfm#errata28 |
| Page 48, HORIZONTAL CURVES AND TANGENTS AT TYPE 2 SAG VERTICAL CURVES, Paragraph 1, Sentence 1 | shown in figure 55 and figure 56 | /publications/research/safety/13077/005.cfm#errata29 |
| Page 50, CMFs FOR COMBINED CRASH SEVERITY LEVELS, Paragraph 1, Sentence 3 | shown in figure 59 | /publications/research/safety/13077/005.cfm#errata30 |
| Report - FHWA-HRT-13-077 | Summary Report - FHWA-HRT-13-078 | Excel Calcuator Tool - HRTM 2130 |
The first edition of the American Association of State Highway and Transportation Officials (AASHTO) Highway Safety Manual (HSM) provides crash modification factors (CMFs) for the safety effects of horizontal curvature and percent grade on rural two-lane highways.(1) However, the HSM does not provide a method to account for the interactions between these effects. Researchers have always presumed that there are interactions between the safety effects of horizontal and vertical alignment, but this has not been demonstrated for specific alignment combinations in a form useful for safety prediction.
This document is a final report highlighting research undertaken to quantify the safety effects of five specific combinations of horizontal and vertical alignment for rural two-lane highways. The research is based on data from the Federal Highway Administration’s Highway Safety Information System (HSIS) for Washington State, including roadway characteristics, horizontal and vertical alignment, traffic volume, and crashes. The outcome is a set of safety prediction models for fatal and injury and property damage only crashes. CMFs representing safety performance relative to level tangents on rural two-lane highways were developed from the models for each of the five combinations of horizontal and vertical alignment to present the results in a form suitable for incorporation in the HSM. This report should be of interest to safety engineers and planners as well as other AASHTO HSM users.
Monique R. Evans
Director, Office of Safety
Research and Development
Notice
This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document. This report does not constitute a standard, specification, or regulation.
The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document.
Quality Assurance Statement
The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.
Technical Report Documentation Page
| 1. Report No.
FHWA-HRT-13-077 |
2. Government Accession No. | 3 Recipient's Catalog No. | ||
| 4. Title and Subtitle
Safety Effects of Horizontal Curve and Grade Combinations on Rural Two- Lane Highways |
5. Report Date January 2014 |
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| 6. Performing Organization Code | ||||
| 7. Author(s)
Karin M. Bauer and Douglas W. Harwood |
8. Performing Organization Report No. 110785.01.001 |
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9. Performing Organization Name and Address MRIGlobal |
10. Work Unit No. (TRAIS) |
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| 11. Contract or Grant No. DTFH61-11-C-00050 |
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| 12. Sponsoring Agency Name and Address
Federal Highway Administration Office of Safety Research and Development 6300 Georgetown Pike McLean, VA 22101-2296 |
13. Type of Report and Period Covered
Final Report December 2010–August 2012 |
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14. Sponsoring Agency Code
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| 15. Supplementary Notes This work was performed under subcontract with the University of North Carolina (UNC) Highway Safety Research Center for Highway Safety Information System (HSIS) under Master Agreement No. 5-555697 Contract No. DTFH61 06 C 000013 and under subcontract for HSIS under Master Agreement No. 5-55771 Contract No. DTFH61 11 C 00050. The UNC Program Manager was David L. Harkey, and the Federal Highway Administration HSIS Program Manager was Carol Tan, Ph.D. |
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| 16. Abstract
This report summarizes the results of research undertaken to quantify the safety effects of five types of horizontal and vertical alignment combinations for rural two-lane highways. The research is based on Federal Highway Administration Highway Safety Information System data for Washington State, including crash records from 2003 to 2008. The outcome is a set of safety prediction models for fatal and injury and property damage only crashes.
To present the results in a form suitable for incorporation in the American Association of State Highway and Transportation Officials Highway Safety Manual, crash modification factors representing safety performance relative to level tangents were developed from these models for each of the five combinations of horizontal and vertical alignment—horizontal curves and tangents on straight grades, horizontal curves and tangents at type 1 crest vertical curves, horizontal curves and tangents at type 1 sag vertical curves, horizontal curves and tangents at type 2 crest vertical curves, and horizontal curves and tangents at type 2 sag vertical curves.(1) |
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| 17. Key Words
Safety, Horizontal curves, Vertical curves, Grade interaction, Crests, Sags, Rural two-lane highways, Crash modeling, Safety performance function, Crash modification factor |
18. Distribution Statement
No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161 |
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19. Security Classification Unclassified |
20. Security Classification Unclassified |
21. No. of Pages
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22. Price N/A |
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| Form DOT F 1700.7 | Reproduction of completed page authorized |
*Modified on November 16, 2014
SI* (Modern Metric) Conversion Factors
CHAPTER 2—STATE OF KNOWLEDGE LITERATURE REVIEW
CHAPTER 3—DATABASE DESCRIPTION
CHAPTER 4—STATISTICAL ANALYSIS
CHAPTER 5—CRASH MODIFICATION FACTORS
CHAPTER 6—CONCLUSIONS AND RECOMMENDATIONS
