SIMULATION OF MIXED TRAFFIC FLOW

Abstract

In present study it has been attempted to develop a Traffic Simulation Model and some other ther associated models to study traffic flow behaviour on a Delhi Metropolitan road corridor which is four lane wide with two way movement. The road system has been divided in four types of small homogenous block namely: Normal, Influence, Station and Intersection blocks. A Normal blocks vehicle moves at its free speed. At station block transit vehicles stop for alighting and boarding of passengers. Intersectional area has been given the name of intersection block. Influence block is for smooth speed and lane transition between two normal or one normal and one station block i.e. a vehicle on this block may accelerate or decelerate. The traffic considered here constitutes of five categories; single and double decker buses, car, three wheeler and mini buses or metador. The effect of traffic moving in_oppoisite direction has been neglected (because of mostly divided carriage way). The simulation model is vehicle interaction model W.hich simulates the interactions between vehicles as they move along the road system. Various flow status categories are: Free Flow, Constrained Flow, and Passing. Various modes of movement in first two categories are: Free Flow mode, Following Started; Following Continued; Following Terminated and Stopped. While Passing status include merging; Passing started and Passing completed modes. When any of certain stipulated conditions for Free Flow is not satisfied vehicle enters into constrained Flowing Status. Various modes adopted by vehicle during this status are: Following Started (deceleration) and Following Continued (Follows slower vehicle ahead). Meanwhile vehicles searches for an opportunity to enter into Passing Status to change its status of movement. It may either merge (Following terminated) into adjoining lane or may change its status if vehicle ahead merges (PASSING STARTED) followed by PASSING COMPLETED. Stopped Mode of vehicle arrives when vehicle stops at station block to serve the passengers. On Normal block all modes except Stopped mode may exist on Influence block for Transit vehicle. Following started and Following Continued mode may exist. Car and three wheeler may move in any mode except Stopped mode on Influence block depending upon Traffic. On Station block all Transit vehicles stop while car and three wheeler may assume any mode. On Intersection block modes are controlled by Single Phasing. In present study programming has been done in FORTRAN on DEC-2C SYSTEM according to flow charts drawn for movement of different vehicles on different blocks and both Time scan and event Scan Technique have been adopted. The model output provides an event file (with increasing Clok time) which includes detail of each manoeuvre_performad___by --ihdividual vehicle. The Simulation Model is calibrated and validated against field data obtained from traffic surveys on a traffic Corridor of Delhi Metropolis. For validation journey time is taken as one of the most important measure of effectiveness and model is found capable enough to reflect the real world data. With validated model Simulation Experiment has been performed to study system responses under different roadway and traffic conditions. Simulation experiments have been performed at varying flow levels but with one compositions of traffic stream. It has also been tried to estimate flow para-meters under the situation When flyovers have been constructed