Modeling

The Cell Transmission Model: Network Traffic

Daganzo, Carlos
1994

This paper shows how the evolution of multicommodity traffic flows over complex networks can be predicted over time, based on a simple macroscopic computer representation of traffic flow that is consistent with the kinematic wave theory under all traffic conditions. After a brief review of the basic model for one link, the paper describes how three-legged junctions can be modeled. It then introduces a numerical procedure for networks, assuming that a time-varying origin-destination table is given and that the proportion of turns at every junction is known. These assumptions are reasonable...

Design, Fabrication and Calibration of a Vehicle Tow Bar for Platoon Drag Measurements: A Working Report

Hong, P.
Browand, F.
Marcu, B.
1997

A longitudinal stability model for a 2 vehicle platoon yields a pair of linearly coupled equations that model the dynamics of the tow bar and the vehicles. Using reasonable approximations, the vehicle separation distance obeys a second order non-linear differential equation with constant coeficients. Spring force and damping are provided by a special shock absorber link. The towbar linkage can be made to serve as a low pass mechanical system. The design spring constant of 60 1bfAn and a damping rate of 200 lbf/ft/sec yield a low-pass system with sufficient damping and a cut of frequency of...

Behavioral Impacts Of Recurring And Incident Congestion And Response To Advanced Traveler Information Systems In The Bay Area: An Overview

Khattak, Asad J.
1993

The objective of this study is to understand how people deal with congestion and how they might respond to a multimodal Advanced Traveler Information System (ATIS). Travelers' route, departure time and mode selection decisions in response to incident and recurring congestion were investigated through a survey of Bay Area automobile commuters. This document summarizes the survey methodology, assesses representativeness of the sample and discusses the initial insights obtained from uni-variate and bi-variate analysis.

User's Manual for Transit ITS Simulator (TRAN-ITS)

Dessouky, Maged
Zhang, Lei
Singh, Ajay
Hall, Randolph
1999

This report describes a simulation model developed to evaluate the impact of using Intelligent Transportation Systems (ITS), such as Global Positioning Systems (GPS) for bus tracking, on controlling buses in wide-area transit networks. Control strategies with ITS will be compared against those without ITS (i.e., they do not rely on communication or tracking). The model is developed using a general-purpose simulation language, AweSim (Pritsker, 1997). The simulation model is generic and independent of any dedicated transit network. The model has high flexibility and can be used to simulate...

Travel Time Estimation on the San Francisco Bay Area Network Using Cellular Phones as Probes

Ygnace, Jean-Luc
Drane, Chris
Yim, Y. B.
de Lacvivier, Renaud
2000

Current traffic travel time estimates are largely based on road sensors embedded in the pavement. Today technical developments in cellular positioning and the spread of wireless phones provide the opportunity to track cell phone equipped drivers as traffic probes. The Federal Communication Commission Phase II mandate for Enhanced-911 (E-911) requires that wireless carriers must provide the location of a 911 wireless call by October 1, 2001 to the Public Safety Answering Point (PSAP), within approximately 125 meters, or under one-tenth of a mile in the majority of situations. The motivation...

A Comparison of Traffic Models: Part II Results

Lo, Hong K.
Lin, Wei-Hua
Liao, Lawrence C.
Chang, Elbert
Tsao, Jacob
1997

This working paper is the second part of a series comparing dynamic traffic flow models. It documents the results of comparison based on the framework defined in Part 1. The traffic models selected for comparison are DINOSAUR, DYNASMART, INTEGRATION, and METS. The areas of comparison comprise four categories: functionality, traffic dynamics, route choice mechanism, and network performance.The first category was compared with a checklist of functions. A total of thirteen test scenarios were constructed to compare models for the last three categories.

Traveler Response to New Dynamic Information Sources: Analyzing Corridor and Area-Wide Behavioral Surveys

Yim, Youngbin
Khattak, Asad J.
Raw, Jeremey
2004

Intelligent Transportation Systems present a well-known innovation opportunity to address urban congestion and allow greater access to transportation networks. New sources of travel information are emerging rapidly and they are likely to significantly impact traveler decisions and transportation network performance. To assess the value and impact of these new sources, this paper develops a comprehensive conceptual model based on information processing and traveler response. Specifically, the model accounts for the effect of information source, content and quality on information access and...

A Probabilistic Model And A Software Tool For AVCS Longitudinal Collision/safety Analysis

Tsao, H. S. Jacob
Hall, Randolph W.
1993

This paper develops a probabilistic model and a software tool for analyzing longitudinal collision/safety between two automated vehicles. The input parameters are the length of the gap between the two vehicles, the common speed prior to failure, the reaction delay of the following vehicle and a bivariate joint distribution of the deceleration rates of the two vehicles. The output includes the probability of a collision and also the probability distribution of the relative speed at collision time. The model is used to compare the safety consequences associated with the platooning and "free-...

Dynamic Traffic Assignment For Automated Highway Systems: A Two-lane Highway With Speed Constancy

Tsao, H. S. Jacob
1996

Dynamic traffic assignment through analytical modeling and optimization has been widely accepted by the IVHS R&D community as a promising traffic control tool for understanding and relieving traffic congestion on conventional highways and city streets. Due to the completely controlled nature of AHS traffic, dynamic assignment of AHS traffic is even more promising. One added dimension of complexity associated with AHS dynamic traffic assignment is lane assignment. Lane changes, for fully utilizing AHS capacity or for exiting, incur disturbances to and hence reduction of longitudinal...

Vehicle Modeling and Verification of CNG-Powered Transit Buses

Hedrick, J. K.
Ni, A.
2004

This report will present the results of the initial study to develop an accurate working model of the 40 foot New Flyer Bus powered by the Cummins C8.3+ 280G CNG engine (Figure 1.1). The main focus of the study is the modeling of the vehicle dynamics using step input acceleration data. Other parts of the research include gear shifting and torque production from the CNG engine, all of which are required to produce a completely simulationcapable bus model.