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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. Problems and Objectives.
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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
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
A Model 332 Cabinet 170 Controller Input File Front Side Back Side
Output Signals Voltage 12V 0V Time Headway Scan Count Note: 12V = W/O Cars 0V = With Cars
System Connection Input File Controller Before 12V Signal Input File LOOPSIM Controller After
SystemComponents • Laptop Computer with a PCMCIA port • Digital I/O Card • Reed Relay Circuits • Cable Connections Cable Connection
System Architecture LOOPSIM 12V Input File Controller
SystemFeatures • Channel Connection Test • Check the operation of every channel before actual tests • Vehicle Arrival Pattern Simulations • Different distribution of vehicle arrival patterns, e.g., Uniform, Normal, and Erlang distribution. • Roadway Traffic Emulations** • Replaying of collected traffic event data
SystemTest Setting • LOOPSIM was tested with a Model 332 controller cabinet installed with a Type 170 controller. • Eight double-loop systems (16 channels)
Test Results : Vehicle Arrival Pattern Simulation • Comparison of Scan Counts & Headway Scan Count Scan Count
Test Results : Roadway Traffic Emulations • Comparison of Binary Outputs Binary Output Binary Output Note : One byte contains the statuses of eight loop detectors at a particular moment.
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
Future works • The feed back function from controller to computer • Add more simulation features • Testing with different other types of controllers and cabinets
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