1. Customized Simulation Modeling Using PARAMICS Application Programming Interface Henry Liu, Lianyu Chu & Will Recker

2. Overview Introduction Why Customize? PARAMICS API Development Plug-ins Developed Wrap-up

3. User Developer Output Interface Input Interface GUI Tools Professional Community Oversight Core Model API Introduction

4. Introduction (Contd.) API provides users with a functional interface Command- based With GUI With API Data Interface Functional Interface Simulation Program

5. Introduction (Contd.) function calls: vehicle related.. link related.. and others user-defined programs Main simulation loop Plugins API data Other applications /APIs Role of a typical API functions

6. Introduction (Contd.)  Customization pushing the limits More on the API…  Plug-and-play environment reusable and generic plugins  API: the “soft key” to the black-box

7. Why Customize? Incident Detection Intelligent Parking Travel Time Prediction Signal Control Systems Transit Priority Electronic Road Pricing Road Maintenance Scheduling & Monitoring Bus Scheduling Assistance TESTBED

8. Why Customize? (Contd.) Network Building Performance Measurement Additional Functionality: ITS Elements Basic Functionality: signals etc Customize

9. PARAMICS API Simulation Loop Overload Functions Override Functions Callback Functions Built-in Functions User Functions

10. PARAMICS API (Contd.) Access via API At every timestep (or at intervals) When an event occurs in simulation Event triggered by user

11. PARAMICS API Development A Hierarchical Approach Provided API Library ATMIS Modules Developed API Library Advanced Algorithms Data Handling Routing Ramp Signal CORBA Databases Adaptive Signal Control Adaptive Ramp Metering Dynamic Network Loading Demand XML

12. Developed Basic API Library Path-based Routing (Para-Dyn) Paramics-CORBA Communication Actuated Signal Controller Time-based Ramp Metering Paramics-MySQL Communication Loop Aggregator Performance Measurement

13. Modules Developed Actuated Signal Control Plugin Inputs: Signal Timing Plan, including phase sequence, initial green, maximum green, unit extension time and system recall phase, etc. Detectors need to be specified and associated with movements to be activated. Standard During-ring Logic Actuated Signal Coordination Interface with some other signal optimization packages such as Transyt7F and SYNCHRO, etc.

14. Modules Developed Ramp Metering Basic Time-based Module: Input: time-of-day ramp control plan such as 6-9 AM, cycle length 5 sec. Logic: n-cars-per-green Advanced Modules: Demand-capacity strategy Percent-occupancy strategy ALINEA BOTTLENECK ZONE

15. Utility Plugins Developed Paramics-MySQL Communication Connecting PARAMICS simulation environment with MYSQL database Includes a set of simple C routines programmed in MYSQL API functions. The MYSQL database can be used in the following two folds: API users can store the simulation outputs to database; During a simulation process, MYSQL database can be used for storing intermediate simulation results, such as aggregated loop data, which can be queried by other external API modules at any time.

16. Utility Plugins Developed Loop Aggregator Input: time interval, smooth factor, detector name Output: MYSQL database or ASCII file volume, percent occupancy, speed, flow, headway

17. Performance Measurement Plugin Utility Plugins Developed To customize performance measurement for run-time interfacing with other tools such as data mining and signal optimization. MOE: vehicle count, travel time, stopped time, vehicle-spent time in a specific speed range, turn counts from intersections, cycle time, individual phase time etc. Data collected at a detector, node, link, corridor, OD pair or network levels, at specified time intervals, for specific type of vehicles where applicable. Output can be in the form of a spreadsheet, text file or on-screen reporting.

18. Wrap up 1. While GUI helps in building a basic simulation network, API helps in customization of various functional aspects of simulation modeling. 2. Plugins provide users with more freedom to interrupt and control simulation processes and hence facilitates overcoming some of the challenges faced in modeling traffic scenarios of the ITS era.

19. Publications 1.Liu, X., Chu, L., and Recker, W., “Paramics API Design Document for Actuated Signal, Signal Coordination and Ramp Control”, California PATH Working Paper, UCB-ITS- PWP-2001-11, University of California at Berkeley, 2001. 2.Chu, L., Liu, X., Recker, W., and Zhang, H. M., “Development of A Simulation Laboratory for Evaluating Ramp Metering Algorithms”, Accepted for the presentation at TRB 2002.