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Publication Number: FHWA-HRT-09-061
Date: February 2010

Simulator Evaluation of Low-Cost Safety Improvements on Rural Two-Lane Undivided Roads: Nighttime Delineation for Curves and Traffic Calming for Small Towns

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FOREWORD

Motor vehicle crashes on the Nation's roadways extract a high toll on American productivity and quality of life. Highway and traffic engineers have been in pursuit of relatively low-cost safety improvements that might have the potential to reduce crashes, save lives, reduce injuries, and lower property damage. For many rural areas, low-cost safety treatments are the only affordable option.

This report describes a driving simulator experiment designed to evaluate two sets of alternative low-cost safety improvements for rural areas. The first set of improvements is directed at enhancing the visibility of curves on rural two-lane undivided roads at night. The second set of improvements is directed at slowing traffic on rural two-lane undivided roads in small towns. This report should be of interest to highway engineers, traffic engineers, highway safety specialists, local planners, researchers, and others involved in the design and operation of rural roadways.

Raymond A. Krammes
Acting 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.

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.

1. Report No

FHWA-HRT-09-061

2. Government Accession No.

3. Recipient's Catalog No.

4. Title and Subtitle

Simulator Evaluation of Low-Cost Safety Improvements on Rural Two-Lane Undivided Roads: Nighttime Delineation for Curves and Traffic Calming for Small Towns
Erin E. Dagnall, and Jason F. Kennedy

5. Report Date

February 2010

6. Performing Organization Code

7. Author(s)

John A. Molino, Bryan J. Katz, Megan B. Hermosillo,

8. Performing Organization Report No.

9. Performing Organization Name and Address

Science Applications International Corporation (SAIC)
8301 Greensboro Drive, M/S T1-12-3
McLean, VA 22102

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

DTFH61-08-C-00006

13. Type of Report and Period Covered

Final Report
January 2007–October 2009

12. Sponsoring Agency Name and Address

Volpe National Transportation Systems Center
55 Broadway, Kendall Square
Cambridge, MA 02142-1093

Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296

14. Sponsoring Agency Code

15. Supplementary Notes

The FHWA Contracting Officer's Technical Representative (COTR) was Thomas Granda (HRDS-07). The FHWA Points of Contact for the Low Cost Safety Improvements Pooled Fund Study were Roya Amjadi and
Carol Tan (HRDS-06).

16. Abstract

This experiment was sponsored by the Low Cost Safety Improvements Pooled Fund Study. It focused on two areas: (1) advanced detection and speed reduction for curves in rural two-lane roads at night and (2) traffic calming for small rural towns during the day. The experiment was conducted in the Federal Highway Administration's (FHWA) Highway Driving Simulator (HDS). Speed reduction in curves yielded the following order of tested treatments (from best to worst): (1) post-mounted delineators (PMDs) enhanced by streaming light-emitting diode (LED) lights slowed drivers down the most (9 mi/h (14.5 km/h)); (2) standard PMDs slowed drivers down by 7 to 8 mi/h (11.3 to 12.9 km/h); and (3) edge lines slowed drivers down by 2 mi/h (3.2 km/h). The same order was obtained for increases in the distance at which drivers were able to identify either the direction or the severity of the curve ahead as follows: streaming LED PMDs increased detection distance the most (560 to 1,065 ft (171 to 325 m)); standard PMDs increased detection distance by 45 to 200 ft (13.7 to 61 m); and edge lines increased detection distance by zero to 25 ft (zero to 7.6 m). PMDs performed better than pavement markings. The streaming PMDs solution offered the greatest potential increase in recognition distance. Speed reduction in towns yielded the following order of tested treatments: (1) chicanes slowed drivers down the most by 4 to 9 mi/h (6.4 to 14.5 km/h); (2) parked cars on both sides of the road slowed drivers 4 mi/h (6.4 km/h); and (3) bulb-outs resulted in only a small speed reduction of 1 mi/h (1.6 km/h) or none at all. In the case of towns, two low-cost safety solutions are worthy of further study: (1) adding painted chicanes to town entrances and (2) providing for and encouraging parking in the town. The results of this experiment do not take into account other hazardous factors that exist in the real world. Therefore, field validation is recommended for most of the above findings.

17. Key Words

Roadway safety, Visibility, Curve navigation, Pavement markings, Delineators, Traffic calming, Bulb-outs, Chicanes, Driving simulators

18. Distribution Statement

No restrictions. This document is available through the National Technical Information Service, Springfield, VA 22161.

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

68

22. Price

Form DOT F 1700.7 (8-72)

Reproduction of completed page authorized

SI* (Modern Metric) Conversion Factors

Table of Contents

EXECUTIVE SUMMARY

Chapter 1. Introduction

Background

Safety Problem

Pooled Fund Study Sponsorship

Candidate Safety Treatments

Research Questions

Curves

Towns

Chapter 2. METHOD

Commonalities for Both Curves and Towns

Experimental Sessions

Participants

Driving Simulator

Common Procedures

Curves

Simulated Safety Improvements for Curves

Procedures Specific to Curves

Towns

Simulated Safety Improvements for Towns

Design of Small Towns and Traffic-Calming Treatments

Research Design

Run-Off Road Countermeasures

Small Town Speeding Countermeasures

Measures of Effectiveness

Chapter 3. Results

Curves

Speed Profiles for Curves

Effects of Possible Interactions

Effects of Treatments

Speed Reductions for Curves

Acceleration Profiles for Curves

Feature Detection for Curves

Towns

Speed Profiles for Towns

Speed Reductions for Towns

Acceleration Profiles for Towns

Chapter 4. Discussion and Summary

Limitations of the Research

Curves

Summary of Findings for Curves

Answers to Research Questions for Curves

Potential Safety Benefits for Curves

Novel Curve Treatment Solution

Recommendations

Towns

Summary of Findings for Towns

Answers to Research Questions for Towns

Potential Safety Benefits for Towns

Recommendations

Conclusion

ACKNOWLEDGEMENTS

References

List of Figures

Figure 1. Photo. FHWA HDS

Figure 2. Screenshot. Curve baseline condition

Figure 3. Screenshot. Edge lines condition

Figure 4. Screenshot. Single side PMDs condition

Figure 5. Screenshot. Both sides PMDs condition

Figure 6. Screenshot. Streaming PMDs condition

Figure 7. Screenshot. Town baseline condition

Figure 8. Screenshot. Parked cars condition

Figure 9. Screenshot. Curb and gutter bulb-outs condition

Figure 10. Screenshot. Painted bulb-outs condition

Figure 11. Screenshot. Curb and gutter chicanes condition

Figure 12. Screenshot. Painted chicanes condition

Figure 13. Screenshot. Plan view of chicane geometry

Figure 14. Graph. Average speed as a function of the distance from the PC for sharp curves

Figure 15. Graph. Average speed as a function of the distance from the PC for gentle curves

Figure 16. Graph. Average speed as a function of the distance from the PC

Figure 17. Graph. Average acceleration as a function of the distance from the PC

Figure 18. Graph. Average curve direction detection distance as a function of drive

Figure 19. Graph. Average curve severity detection distance as a function of drive

Figure 20. Graph. Average speed as a function of the distance from the beginning of the town

Figure 21. Graph. Average acceleration as a function of the distance from the beginning of the town

List of Tables

Table 1. Distribution of research participant characteristics

Table 2. Curve roadway characteristics

Table 3. Luminance of nighttime visual stimuli

Table 4. Town roadway characteristics

Table 5. Average speed and speed reduction advantage in curves (mi/h)

Table 6. Percentage of correct responses and no change responses for feature detection

Table 7. Average feature detection distance and distance advantage for curves

Table 8. Average speed and speed reduction advantage in towns (mi/h)

Table 9. Estimated safety advantages and rank ordering of treatments for curves

Table 10. Estimated speed reductions and rank ordering of treatments for towns

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