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REPORT
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Publication Number:  FHWA-HRT-14-058    Date:  April 2015
Publication Number: FHWA-HRT-14-058
Date: April 2015

 

Field Evaluation of Detection-Control System

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FOREWORD

Intersections are major components of the roadway system where planned points of conflict occur between road users who need to cross paths. Over the past several years, an average of 21 percent of the fatalities and roughly 50 percent of the serious injuries on the U.S. roadway system occurred at intersections.

Strategies to address intersection safety are diverse and targeted. For isolated rural, high-speed signalized intersections, dilemma zone related angle and rear-end crashes are a major concern. The dilemma zone is defined as a length of roadway on the approach to an intersection, or a time period while driving toward the intersection, within which drivers have difficulty deciding whether to stop or to continue moving when presented with a yellow signal indication.

This report discusses one solution to the above problem called detection-control system (D-CS). D-CS is intended for use at isolated, full-actuated intersections on high-speed roadways where the major road approach has an 85th-percentile speed (or posted speed limit) of 45 mi/h or higher. D-CS requires lane-by-lane vehicle detection on major approaches, and presence detection on minor approaches. Field tests show that D-CS can effectively reduce dilemma zone induced red light running and the frequency of reaching the designated maximum green time for the major road green phase (max-out).

Monique 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.

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.

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TECHNICAL REPORT DOCUMENTATION PAGE

1. Report No.
FHWA-HRT-14-058

2. Government Accession No.

3. Recipient’s Catalog No.

4. Title and Subtitle Field
Evaluation of Detection-Control System

5. Report Date
April 2015

6. Performing Organization Code

7. Author(s)
Dan Middleton, Ryan Longmire, Hassan Charara, Jim Bonneson, Srinivas Geedipally, and Myunghoon Ko

8. Performing Organization Report No.
N/A

9. Performing Organization Name and Address
Texas Transportation Institute The Texas A&M University System College Station, Texas 77843-3135

10. Work Unit No. (TRAIS)

11. Contract or Grant No.
DTFH61-08-C-00033

12. Sponsoring Agency Name and Address
USDOT-FHWA, Turner-Fairbank Highway Research Center
Office of Safety Research and Development
6300 Georgetown Pike, McLean, VA 22101-2296

13. Type of Report and Period Covered
Final Report: September 2008 to March 2012

14. Sponsoring Agency Code
FHWA

15. Supplementary Notes
Project Title: Field Evaluation of the Effectiveness of Detection-Control System
The FHWA Office of Safety Research and Development funded this research. The Contracting Officer’s Representative is Dr. Wei Zhang. The following people served as Technical Panel Members on this contract: Joe Bared, Jeff Shaw, and Tim Taylor.

16. Abstract
In this research, a field evaluation of the Detection-Control System (D-CS) was conducted at eight sites located in four States. D-CS is similar to a traditional advance detector system in that it uses information from detectors located upstream of the intersection to extend the green phase. However, it differs from traditional advance detector systems because it monitors individual vehicles on the intersection approach on a lane-by-lane basis and on a vehicle length basis. It uses this information to predict the best time to end the major-road through phase. The D-CS software continuously evaluates and updates this prediction in real time. The prediction is based on the number of vehicles currently in (or predicted to soon arrive in) the dilemma zone as well as the number of conflicting phases with a call for service.

Based on the findings to date, D-CS is successful in reducing crashes in almost all cases where it has been evaluated. Crash surrogate measures of effectiveness provide corroborating evidence for this conclusion. Findings from a regression analysis for 1-h periods indicate that the after study periods experienced 82percent fewer red-light violations, 73 percent fewer vehicles in the dilemma zone, and 51 percent fewer max-outs than the before study periods. State crash data indicate that by combining angle plus rear-end crashes (because of small sample sizes), D-CS reduced crashes by 9 percent. This result is not statistically significant at the 95-percent level. Given the supportive evidence that D-CS improves safety, other controller manufacturers might be willing to include D-CS as an option in their controllers. The Government is already considering ways to encourage signal controller manufacturers to include the D-CS algorithm in their signal controllers.

17. Key Words
dilemma zone, detection, detection-control system, traffic signals, inductive loops

18. Distribution Statement
No restrictions. This document is available to the public through NTIS: National Technical Information Service http://www.ntis.gov
19. Security Classif.(of this report)
Unclassified		 20. Security Classif.(of this page)
Unclassified		 21. No. of Pages
114		 22. Price
Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

 

SI* (Modern Metric) Conversion Factors

TABLE OF CONTENTS

CHAPTER 1. INTRODUCTION AND BACKGROUND

INTRODUCTION

BACKGROUND

D-CS

Overview

Lane-by-Lane Detection and Vehicle-by-Vehicle Monitoring

Previous Implementation Status and Site Characteristics

PREVIOUS EVALUATION OF D-CS PERFORMANCE

Earlier Findings

Conclusions Based on Earlier Installations

CHAPTER 2. RESEARCH METHODOLOGY

INTRODUCTION

Study 1: Performance Monitoring of Dilemma Zone Occupancy

Study 2: Before-After Crash Data Study

Study 3: Before-After Crash Surrogate Study

Study 4: Upper Limit Study

FIELD SITE SELECTION PLAN

Site Selection Criteria

Site Selection Process

METHODOLOGY FOR FIELD DATA COLLECTION

SITES SELECTED FOR ANALYSIS

Florida Sites

Illinois Sites

Louisiana Site

Texas Sites

ANALYSIS METHODOLOGY

CHAPTER 3. DATA COLLECTION SYSTEM

INTRODUCTION

DATA COLLECTION SOFTWARE

RTTDCS

Wavetronix™ Advance System

DATA COLLECTION HARDWARE

Equipment Available from the Government

Equipment Purchased Using Project Funds

Description of Equipment Used

CHAPTER 4. DATA ANALYSIS RESULTS

INTRODUCTION

DATA COLLECTION SITES

Sites 1, 2, and 3 Information

Sites 4 and 5 Information

Site 6 Information

Sites 7 and 8 Information

TRAFFIC DATA ANALYSIS

Studies 1 and 3 Results

Study 4 Results

Study 2 Results

Safety Effects of D-CS

CHAPTER 5. D-CS IMPLEMENTATION GUIDE

INTRODUCTION

Overview of D-CS

D-CS Algorithm.

Vehicle Status Component

Phase-Status Component

Implications of D-CS

D-CS Input Screens

Speed Detectors

Lane Setup

Status

Recommended D-CS Settings

Summary

INDUCTIVE LOOP FIELD INSTALLATION PROCESS

Vehicle Detection System Components

APPLICATION CONSIDERATIONS

CHAPTER 6. CONCLUSIONS AND RECOMMENDATIONS

INTRODUCTION

CONCLUSIONS

Related to Methodology

Related to Crash Surrogate Measures

Related to Upper Limit Study

Related to Crash Data Analysis

RECOMMENDATIONS

Application Considerations

APPENDIX A: PARTIAL FULL-DAY RESULTS

Full Day Results

APPENDIX B: EXPLANATION OF DATA TABLE HEADERS

Red-Light-Running Data File with .RLR Extension

Phase Status Data File with .PHS Extension

WSSA (.WAS) Files

Detector .SBD File (Detector On Events)

D-CS Advance Detector Trap .SPD Files

REFERENCES

LIST OF FIGURES

Figure 1. Illustration. D-CS components

Figure 2. Illustration. D-CS detection design

Figure 3. Photo. Naztec cabinet in Florida with D-CS monitoring equipment

Figure 4. Map. Fort Lauderdale D-CS sites

Figure 5. Map. Intersection layout at U.S. 27 and Griffin Rd

Figure 6. Map. Intersection layout at U.S. 27 and Johnson Rd

Figure 7. Map. Intersection layout at U.S. 27 and Pines Blvd

Figure 8. Chart. Phase sequence for U.S. 27/Pines Blvd

Figure 9. Chart. Phase sequence for U.S. 27/Johnson St

Figure 10. Map. Peoria, IL, D-CS sites

Figure 11. Map. Intersection layout at U.S. 24 and Cummings Ln

Figure 12. Map. Intersection layout at U.S. 24 and Main St

Figure 13. Map. Louisiana D-CS site

Figure 14. Map. Intersection layout at LA 3235 and LA 3162

Figure 15. Map. San Antonio, TX, D-CS site

Figure 16. Map. Intersection layout at U.S. 281/E. Borgfeld Dr

Figure 17. Map. Waco, TX, D-CS site

Figure 18. Map. Intersection layout at U.S. 84/Speegleville Rd

Figure 19. Equation. Variance of distribution

Figure 20. Equation. Expected red-light-running frequency

Figure 21. Graph. Comparison of observed and predicted red-light-running frequency

Figure 22. Graph. Comparison of observed and predicted number of vehicles in the dilemma zone

Figure 23. Graph. Comparison of observed and predicted max-out frequency

Figure 24. Equation. Expected number of crashes and variances for after period

Figure 25. Equation. Sum of predicted crashes and its variance

Figure 26. Equation. Sum of actual crashes for treated sites after period

Figure 27. Equation. Index of effectiveness

Figure 28. Equation. Variance of estimated safety-effectiveness

Figure 29. Equation. Standard error of safety-effectiveness

Figure 30. Equation. Number of crashes based on the Poisson-gamma model

Figure 31. Equation. Mean of the number of crashes

Figure 32. Equation. Functional form of safety performance

Figure 33. Equation. SPF for TOT crashes

Figure 34. Equation. SPF for FI crashes

Figure 35. Equation. SPF for angle plus RE crashes

Figure 36. Chart. Detection-control algorithm flowchart

Figure 37. Chart. Vehicle-status component algorithm flowchart

Figure 38. Chart. Phase-status component algorithm flowchart

Figure 39. Illustration. Comparison of dilemma zones for fast and slow vehicles

Figure 40. Illustration. Speed trap configuration

Figure 41. Illustration. Trap distance measurement

Figure 42. Illustration. Numbering of inductive loops in the roadway

LIST OF TABLES

Table 1. Implementation site characteristics

Table 2. Before-after delay and stop frequency comparison

Table 3. Before-after red-light violation comparison

Table 4. Before-after severe crash frequency comparison

Table 5. Summary of traffic monitoring and data storage equipment

Table 6. Sites selected for data collection

Table 7. Information on sites selected for data collection

Table 8. Dates for field data collection

Table 9. Synchro results for morning peak at U.S. 281/Borgfeld Dr

Table 10. Synchro results for afternoon peak at U.S. 281/Borgfeld Dr

Table 11. Equipment list available from FHWA

Table 12. Equipment purchased with project funds

Table 13. Controller settings U.S. 27/Griffin Rd.—before

Table 14. Controller settings U.S. 27/Griffin Rd.—after D-CS

Table 15. Controller settings for U.S. 27/Johnson Rd.—before D-CS

Table 16. Controller settings for U.S. 27/Johnson Dr.—after D-CS

Table 17. Controller settings for U.S. 27/Pines Blvd.—before D-CS

Table 18. Controller settings for U.S. 27/Pines Blvd.—after D-CS

Table 19. Controller settings for U.S. 24/Cummings Ln.—before D-CS

Table 20. Controller settings for U.S. 24/Cummings Ln.—after D-CS

Table 21. Controller settings for U.S. 24/Main St.—before D-CS

Table 22. Controller settings for U.S. 24/Main St.—after D-CS

Table 23. Controller settings for LA 3235/LA 3162—before D-CS

Table 24. Controller settings for LA 3235/LA 3162—after D-CS

Table 25. Controller settings for U.S. 281/Borgfeld Dr.—before D-CS, Eagle controller

Table 26. Controller settings for U.S. 281/Borgfeld Dr.—before D-CS, Naztec controller

Table 27. Controller settings for U.S. 281/Borgfeld Dr.—after D-CS, Naztec controller

Table 28. Controller settings for U.S. 84/Speegleville Rd.—before D-CS

Table 29. Controller settings for U.S. 84/Speegleville Rd.—after D-CS

Table 30. Site summary information

Table 31. Before-after database summary—total observations

Table 32. Before-after database summary—red-light-running violation rates

Table 33. Calibrated red-light violation model statistical description

Table 34. Calibrated dilemma zone model statistical description

Table 35. Calibrated max-out model statistical description

Table 36. Upper Limit Study summary

Table 37. Upper-limit database summary—total observations

Table 38. Number of crashes at treatment and comparison sites

Table 39. Summary statistics of crashes and traffic flow

Table 40. Parameter estimation for SPF

Table 41. Average safety effect of D-CS based on crash data

Table 42. Speed detector screen

Table 43. Lane setup screen

Table 44. Status screen

Table 45. D-CS recommended settings

Table 46. Settings for Reno A&E model S-1200-SS

Table 47. Guidance on the use of D-CS

Table 48. Summary of partial 24-h operations data

Table 49. Full-day data results for U.S. 24/Cummings Ln

Table 50. Full-day data results for U.S. 24/Main St

Table 51. Full-day data results for LA 3162/LA 3235

Table 52. Full-Day Data Results for U.S. 27/Griffin Rd

Table 53. Red-light-running (.RLR) files

Table 54. Phase status (.PHS) files

Table 55. The WSSA (.WAS) files

Table 56. Detector Status .SBD files

Table 57. Detector .SBD file (detector off events)

Table 58. D-CS advance detector trap .SPD files

 

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