<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.trb.org/common/TRIS Suite/feeds/rss.aspx?tc=NN%3AUhdk" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>A Simple Example of a Two-Dimensional Model for Traffic: Discussion about Assumptions and Numerical Methods</title><link>http://pubsindex.trb.org/view/1494764</link><description><![CDATA[This article presents a two-dimensional (2D) macroscopic model for traffic flow on a network. We considered a 2D conservation law in which we suggested a new method to estimate the direction of the velocity using only information and properties of the network. We present an algorithm for the computation of the 2D velocity on the network and present numerical simulations. Moreover, the numerical approximation of the 2D equation was carried out using an operator and splitting method and we present the results of some simulations on realistic networks. Lastly, we propose a comparison with the well-known cell transmission model method.]]></description><pubDate>Thu, 01 Feb 2018 09:46:06 GMT</pubDate><guid>http://pubsindex.trb.org/view/1494764</guid></item><item><title>Particle Filter Approach for Real-Yime Freeway Traffic State Prediction</title><link>http://pubsindex.trb.org/view/1129846</link><description><![CDATA[The research presented in this paper develops a multi-step particle filter traffic state prediction algorithm using spot speed measurements. The traditional Lighthill-Whitham-Richards (LWR) flow continuity equation is combined with the Van Aerde traffic stream model to generate a new speed-based partial differential equation (PDE). The numerical solution of the PDE is obtained using the Godunov discretization scheme within a particle filter to generate a time series equation that characterizes the temporal and spatial relationship of traffic speed data. This speed formulation is further enhanced by incorporating ramp flows and enhancing the boundary conditions. The numerical solution and near-term prediction accuracy (5-minute prediction) of the new speed formulation is compared with the conservative density formulation derived from LWR. Although the proposed speed formulation is non-conservative and not equivalent to the solution of LWR under the same initial and boundary conditions, it produces significant enhancements in the traffic state predictions. Specifically, the prediction error using simulated I-66 data is in the range of 3.0 to 4.5 km/h for a 5-minute prediction horizon. This error is approximately half the prediction error of the LWR formulation. Similarly, the traffic stream density prediction error is approximately half that of the LWR formulation.]]></description><pubDate>Thu, 29 Mar 2012 07:14:51 GMT</pubDate><guid>http://pubsindex.trb.org/view/1129846</guid></item><item><title>HYDRODYNAMIC APPROACHES</title><link>http://pubsindex.trb.org/view/116106</link><description><![CDATA[THE APPLICATION IS DISCUSSED OF FLUID FLOW PRINCIPLES TO THE TRAFFIC STREAM. REGARDING TRAFFIC AS A HYDRODYNAMIC FLOW BASES THE ANALYSES ON A PARTIAL DIFFERENTIAL EQUATION EXPRESSING THE CONSERVATION OF MATTER AND AN ASSUMED EMPIRICAL RELATION BETWEEN THE FLOW AND CONCENTRATION. THE SOLUTION OF THE EQUATION INDICATES THAT DISCONTINUITIES IN THE TRAFFIC FLOW ARE PROPAGATED IN A MANNER SIMILAR TO SHOCK WAVES IN THE THEORY OF COMPRESSIBLE FLUIDS. AN APPROACH IS PRESENTED TO THE BEHAVIOR OF SHOCK WAVES IN THE TRAFFIC STREAM. THE LIGHTHILL-WHITHAM AND RICHARDS THEORIES ARE COMPARED.]]></description><pubDate>Fri, 17 Aug 2001 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/116106</guid></item><item><title>SIMULATION OF CROWD BEHAVIOR AND MOVEMENT: FUNDAMENTAL RELATIONS AND APPLICATION</title><link>http://pubsindex.trb.org/view/365609</link><description><![CDATA[A model of crowd behavior and movement in the Jamarat system, which is a critical bottleneck during the Hajj, the Muslims' annual pilgrimage to Makkah, Saudi Arabia, is described.  The model consists of a set of partial differential equations that are solved numerically following a discretization of time and space.  Mathematical relations are defined for three fundamental processes:  (a) radial movement, (b) lateral movement, and (c) stoning process. These relations are developed and calibrated using actual measurements taken at the site.  As a result, a bidirectional speed-concentration model is developed to describe radial movement, revealing that the impedance to movement from facility users going in the same direction is about twice that from those going in the opposite direction. The overall model is applied to the evaluation of possible design and control strategies aimed at improving the efficiency and throughput of the system.]]></description><pubDate>Thu, 30 Apr 1992 00:00:00 GMT</pubDate><guid>http://pubsindex.trb.org/view/365609</guid></item></channel></rss>