Investigation the Effect of Heavy Vehicles on Capacity of Signalized Intersections Based on Bayes' Theorem

© 2014 American Society of Civil Engineers.Heavy vehicles, considering their size and low rate of acceleration and/or deceleration in traffic stream, are responsible for numerous negative effects on other vehicles. As a result, the capacity of signalized intersections declines significantly as the ratio of heavy vehicles in traffic flow is increased. In literature, there are different methods that are used with the goal of determining those negative effects. HR (Headway Ratio) is one of the most frequently used methods amongst all other methods. In this study, HR method was extended by substituting independent probability combinations set of vehicle types for percentage (%) of heavy vehicles in heavy vehicles adjustment factor FHV equation. Also, four independent car-following combinations probability were considered: heavy vehicle following passenger car (H-C), passenger car following heavy vehicle (C-H), passenger car following passenger car (C-C), and heavy vehicle following another heavy vehicle (H-H). Probabilities of occurrence of each combination for percentage (%) of heavy vehicles were calculated by using the Bayes' theorem. The comparisons of results with different studies indicate that there is a significant difference between suggested new model and other studies on high heavy vehicle ratio condition. Moreover, the results showed that the proposed new model may give more accurate results being used in the intersections with high ratio of heavy vehicles

APPLICATION OF COMPUTER PROGRAM CARSIM FOR MODELLING SINGLE AND DOUBLE LANE CHANGE MANOEUVRES / TAIKOMOSIOS PROGRAMOS „CARSIM“ PRITAIKYMAS, MODELIUOJANT VIENGUBĄ IR DVIGUBĄ JUDĖJIMO JUOSTOS PAKEITIMO MANEVRĄ

The paper analyzes the possibilities of using computer aided modelling programs for developing new cars to achieve better dynamical properties of control over vehicles. The article shortly reviews the behaviour of young and experienced drivers and models describing it. The paper covers the process of turning car steering wheel, considers acceptable values of lateral acceleration comfortable for a car driver and all car passengers and presents computer aided modelling program CarSim used for displaying single and double lane change manoeuvres at various speeds on dry asphalt. The given charts, including data about steering wheel angle and lateral acceleration values indicate single and double lane change manoeuvres performed by a car. Also, the values of longitudinal and lateral forces of each wheel during the double lane change manoeuvre are provided. Santrauka Straipsnyje nagrinėjamos kompiuterinių modeliavimo programų pritaikymo galimybės automobilių konstrukcijoms tobulinti, dinaminėms savybėms gerinti. Trumpai minimi vairuotojo elgseną aprašantys mokslininkų jau sukurti modeliai. Aptariamas vairo rato pasukimo procesas, pateikiamos priimtinos vairuotojui ir automobilio keleiviams nesudarančios diskomforto skersinio pagreičio reikšmės. Atliekama trumpa taikomosios kompiuterinio modeliavimo programos „CarSim“ apžvalga. Šia programa atlikti viengubo ir dvigubo judėjimo juostos pakeitimo manevrai, esant skirtingiems automobilio judėjimo greičiams ant sauso asfalto. Pateikti vairo rato pasukimo, skersinių pagreičių reikšmių grafikai. Taip pat pateiktos visus ratus veikiančių išilginių ir skersinių jėgų bei ratų slydimo reikšmės esant 90 km/h greičiui. Raktiniai žodžiai: judėjimo juosta; manevras; skersinis pagreitis; modeliavimo programa; vairo pasukimas; slydimo kampa