Interfacing NGSIM Lane Selection Algorithm with TSIS/CORSIM Li Zhang, Ph.D., P.E. Guanghua Zhang, JiZhan Gou Fatemeh Sayyady, Di Wu & Fan Ye January 20, 2007

Introduction  TSIS/CORSIM is one of the best popular traffic simulation software package in use by many traffic engineers.  NGSIM now has the Lane Selection Model (LSM) available which describes the freeway lane changing behavior  Interfacing NGSIM Lane Selection Algorithm with TSIS/CORSIM

Outline  Introduction  System Architecture  Theoretic Issues Algorithms: Comparison Randomness  Examples on Lane Change  Interface Verification  Project Progress  Summary

System Architecture TShell (TSIS) CORSIM Driver Component CORSIM Server Exported Functions CORSIM Exported Memory RTE NGSIM Call RTE Functions Read Write

Interface Options Road Properties Vehicle Properties Driver Properties Lane Information RTE NGSIM Translator Road Properties Vehicle Properties Driver Properties LSA NGSIM CORSIM Language RTE CORSIM Shared Memory

Recommended Interface CORSIM Component Service Road Vehicle Driver Control/Detector NGSIM Component Properties Vehicle-> UpdateLaneInf Translator

CORSIM Lane Change Model Kinematics Model Subtle Technical Influences (If/Then) Complex Modeling Rule Exceptions (If/Then) Simple Principles & Rules (If/Then)

CORSIM Discretional Lane Change  Supply Motivation/Intolerable Speed: desire to perform lane change>a random number Advantage: gaining in making lane change loss in remaining in current lane Urgency: Urgency and Impatient Factor  Demand: Acceptable Deceleration

CORSIM Implementation  Mandatory Lane Change Motivation and Advantage are obvious Acceptable Deceleration calculation is the function of different reasons (lane drop/exit)  Anticipatory Lane Change Motivation is obvious Advantage is the function of volume  Hiatus Period: unsafe/overlap tolerance  Shadow vehicles: an extra vehicle on candidate lane during Hiatus Period

NGSIM  Demand Logit choice/Utility function model  Weighted factors: distance, space, density, path plan (exit), driver aggressiveness Implementation  Explicit lane choice: relative utilities of current, all left side lanes, and all right side lanes  Highest lane as target lane  Critical Gap vs. available gap Driver aggressiveness Speed difference Random disturbance

Comparison (1)  Kinematics (+ If/then) vs human driving model (utility choice)  CORSIM Shadow vehicle + hiatus period Hard coded many parameters Explicit Lane changes mandatory/discretional/Anticipatory Microscopic comparison with vehicle trajectory data in BW PKW video

Comparison (2)  NGSIM Considers utilities across all lanes Integrated mandatory/discretionary lane changes Code to implement highest lane as target lane is not found to support the claim Weights may need to be calibrated from vehicle trajectory data, how? Time to perform lane change is not found in the model.

Randomness  CORSIM Driver type Motivation Seed? Not good enough Random number generator, good  NGSIM Driver aggressiveness Random disturbance in utility function Seed: Computer Internal Clock Time Random number generator: no documentation

NGSIM/LSA Using CORSIM Data  CORSIM Provide Enough Data?  Observe Lane Change in TRAFVU 3 Discretional+3 Mandatory  A Utility Program is developed to capture data for Lane Change  Manually Calculate the Lane Changes In CORSIM/NGSIM  NGSIM Makes Mandatory Changes as Well!

Interface Design Verification

Progress  NGSIM LSM and FRESIM lane changing algorithm comparison  Manually calculate 3 cases in each algorithm.  Interface RTE program to change the VLANE value (show video/TRAFVU)  Pseudo-code of the NGSIM algorithm Understand the theory

Progress  System Architecture about Interface  Research on Both Algorithms  Theoretic Issues Algorithms/Randomness  Manually Calculation of 6 NGSIM Examples using CORSIM Data  Verified Interface  Pseudo-code of the NGSIM algorithm Understand the theory

Future Work  Finish Coding

Recommendation for NGSIM Project  An collection of source code (compliable), consistent documentation and instructions  An executable file and data set, output vehicle trajectory data, intermediate utility function data, gap data etc.  Examples and Excel Calculations  Improved documentations  Data dictionary and programmers guide Variables Constant Functions Class Comments

Contact Li Zhang, Ph.D., P.E. Assistant Professor Mississippi Transportation Research Center Department of Civil Engineering Mississippi State University (662)