Detector Technology Evaluation Dr. Peter T. Martin, Associate Professor University of Utah Yuqi Feng, Xiaodong Wang Research Assistants Department of Civil and Environmental Engineering University of Utah Traffic Lab 122 South Central Campus Drive November 2003 Acknowledgements The research presented in this paper was supported by finding from the Mountain Plains Consortium (U.S. Department of Transportation) and the Utah Department of Transportation through the Utah Transportation Center. Disclaimer The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented. This document is disseminated under the sponsorship of the Department of Transportation, University Transportation Centers Program, in the interest of information exchange. The U.S. Government assumes no liability for the contents or use thereof. ii TABLE OF CONTENTS 1. INTRODUCTION....................................................................................................................1 2. PROJECT GOALS AND OBJECTIVES.................................................................................3 3. TRAFFIC DATA NEEDS AND DETECTOR APPLICATIONS.............................................5 3.1 Traffic Data Needs ............................................................................................................5 3.2 Detector Applications ........................................................................................................8 3.2.1 Historical Data Collections .....................................................................................8 3.2.2 Real-time Data Collections .....................................................................................8 3.3 Current Practices With Detector Technologies ..................................................................12 3.3.1 Surveys on Departments of Transportation .............................................................12 3.3.2 Guidelines and Standards ......................................................................................17 4. STATE-OF-THE-ART DETECTOR TECHNOLOGIES ......................................................19 4.1 Intrusive Detector Technologies.......................................................................................19 4.1.1 Inductive Loop .....................................................................................................19 4.1.2 Magnetic Detector ................................................................................................23 4.1.3 Pneumatic Road Tube...........................................................................................26 4.1.4 Piezoelectric ........................................................................................................27 4.1.5 Weigh-in-Motion (WIM) ......................................................................................29 4.2 Non-intrusive Detector Technologies................................................................................33 4.2.1 Active and Passive Infrared...................................................................................33 4.2.2 Microwave Radar.................................................................................................36 4.2.3 Ultrasonic and Passive Acoustic ............................................................................38 4.2.4 Video Image Processing (VIP)..............................................................................40 4.2.5 Combined Detector Technologies..........................................................................45 4.3 Off-roadway Technologies ..............................................................................................45 4.3.1 Probe Vehicle ......................................................................................................45 4.3.2 Remote Sensing ...................................................................................................49 4.4 Manual Counting Equipment ...........................................................................................49 4.5 Pedestrian and Bicycle Detection .....................................................................................51 References ...........................................................................................................................54 5. DETECTOR TECHNOLOGY EVALUATION AND SELECTION......................................57 5.1 Data Type.......................................................................................................................57 5.2 Data Accuracy................................................................................................................62 5.2.1 Field Evaluation Results .......................................................................................66 5.2.2 Environmental and Traffic Impacts........................................................................77 5.2.3 Best Performance Technologies for Traffic Monitoring and Intersection Signal Control Applications .........................................................................................83 5.3 Ease of Installation ..........................................................................................................85 5.4 Cost ............................................................................................................................91 5.5 Other Issues.................................................................................................................. 103 5.6 Advantages and Disadvantages ...................................................................................... 107 5.7 Procedure of Detector Technology Selection................................................................... 109 5.7.1 Permanent Application ....................................................................................... 109 5.7.2 Temporary Application ....................................................................................... 116 References ......................................................................................................................... 118 iii 6. CONCLUSIONS..................................................................................................................121 7. RECOMMENDATIONS......................................................................................................123 APPENDIX: VENDOR LISTS IN THE REPORT ..................................................................125 iv LIST OF FIGURES Figure 3.1: Actuated Isolated Intersection Signal Control..........................................................9 Figure 3.2: Traffic Responsive Ramp Metering Control System...............................................11 Figure 4.1: Principal Components of an Inductive Loop Detector.............................................20 Figure 4.2: Preformed Inductive Loop....................................................................................21 Figure 4.3: Inductive Loop Detectors....................................................................................22 Figure 4.4: Distortion of Earth’s Magnetic Field Created as a Vehicle Enters and Passes Through the Detection Zone of a Magnetic Sensor. ..............................................24 Figure 4.5: SPVD .................................................................................................................25 Figure 4.6: 3M™ Canoga™ Vehicle Detection System...........................................................25 Figure 4.7: JAMAR TRAX I PLUS.......................................................................................27 Figure 4.8: A Typical Piezocable Configuration......................................................................28 Figure 4.9: Kistler LINEAS Quartz Sensor.............................................................................28 Figure 4.10: Comparison Between Ordinary Piezocables and LINEAS Quartz Sensors .............29 Figure 4.11: A Bending Plate.................................................................................................30 Figure 4.12: A Load Cell WIM System..................................................................................31 Figure 4.13: Truck Driving Over Portable Capacitive Mat WIM System..................................31 Figure 4.14: Typical Portable Fiber Optics Sensor Installation.................................................32 Figure 4.15: Laser Detector Beam Geometry..........................................................................33 Figure 4.16: Emission and Reflection of Energy by Vehicle and Road Surface .........................34 Figure 4.17: Passive Infrared Detectors..................................................................................35 Figure 4.18: Autosense II......................................................................................................35 Figure 4.19: Microwave Detector Operation ...........................................................................36 Figure 4.20: True Presence Microwave Radar Detectors..........................................................37 Figure 4.21: Doppler Microwave Radar Detectors ..................................................................38 Figure 4.22: Ultrasonic Detectors...........................................................................................39 v Figure 4.23: Passive Acoustic Detectors.................................................................................40