1. Development of An Affordable Loop Detector Simulator (LOOPSIM) for In- Laboratory Traffic Research and Training Patikhom Cheevarunothai, Dr.Yinhai Wang & Dr. Nancy L. Nihan Presented by Cheevarunothai Patikhom (Num) University of Washington

2. Problems and Objectives  Live loop detector inputs may not be available in laboratories where hardware and software need to be tested.  Uncontrollable traffic streams on freeways  High total testing cost  Create a system that can simulate calls from loop detectors without having physical loops in laboratories, to test algorithms executable in the controller or test the performance and accuracy of traffic data collection systems

3. A Model 332 Cabinet 170 Controller Input File Front SideBack Side

4. Output Signals 12V Voltage 0V Time 0V = With Cars Note: 12V = W/O Cars HeadwayScan Count

5. System Connection Input FileController LOOPSIM 12V Signal Input FileController Before After

6. System Components  Laptop Computer with a PCMCIA port  Digital I/O Card  Reed Relay Circuits  Cable Connections Cable Connection

7. System Architecture Input FileController 12V LOOPSIM

8. System Features 1)Channel Connection Test  Check the operation of every channel before actual tests 2)Vehicle Arrival Pattern Simulations  Different distribution of vehicle arrival patterns, e.g., Uniform, Normal, and Erlang distribution. 3)Roadway Traffic Emulations**  Replaying of collected traffic event data

9. Program User Interface

10. System Test Setting  LOOPSIM was tested with a Model 332 controller cabinet installed with a Type 170 controller.  Eight double-loop systems (16 channels)

11. Test Results : Vehicle Arrival Pattern Simulation Scan Count  Comparison of Scan Counts & Headway

12. Test Results : Roadway Traffic Emulations Binary Output  Comparison of Binary Outputs Note : One byte contains the statuses of eight loop detectors at a particular moment.

13. Advantages  Economical system suitable for in-laboratory traffic system testing (total cost $400)  Easy-to-built system architecture  Precise real-time performance at 60 Hz or higher  Capability to control traffic characteristics in line with the purpose of testing or training  Simple to use the replayed data as ground truth data for evaluating the performance of systems or estimations models

14. Future works  The feed back function from controller to computer  Add more simulation features  Testing with different other types of controllers and cabinets

15. Conclusions  LOOPSIM makes live loop inputs available in laboratories for traffic research and training  Test results show that LOOPSIM is reliable and accurate  Affordable system for research institutes and universities