ITS Berkeley

Requiem for Second-Order Fluid Approximations of Traffic Flow

Carlos Daganzo
1995

Although the “first order” continuum theory of highway traffic proposed by Lighthill and Whitham (1955) and Richards (1956)—the LWR model—can predict some things rather well, it is also known to have some deficiencies. In an attempt to correct some of these, “higher order” theories have been proposed starting in the early 70s. Unfortunately, the usefulness of these improvements can be questioned. This note describes the logical flaws in the arguments that have been advanced to derive higher order continuum models, and shows that the proposed high order modifications lead to a fundamentally...

The Variance of the Number of Customers in an Infinite-Server Queueing System with an Arbitrarily Correlated Arrival Process

Carlos Daganzo
Diez-Roux, Esteban
1995

Motivated by a container storage problem at seaports, this paper examines the infinite-server queueing model with a (second order) stationary but arbitrarily correlated arrival process. It starts with a description of the application context, including an explanation of why non-standard inputs and service times arise in certain container storage problems. As further illustration, formulas characterizing the input and service processes for a particular situation are then presented and justified, together with the simple container accumulation variance formula that follows from the general...

Dymanic Traffic Assignment With Queues For ATIS : Final Report For Project MOU 90

Carlos Daganzo
1996

This document reports on a project whose overall objective was to develop a traffic flow model capable of predicting the evolution of multicommodity (multiple destination) network traffic flows consistent with the hydrodynamic theory of traffic flow. The output of this research should enhance the realism of modeling capabilities in representing traffic flows and especially physical queues. This should provide a solid platform for the evaluation of Intelligent Transportation Systems (ITS) improvements, environmental impacts, and dynamic control strategies. In particular, it holds...

Steady State Conditions on Automated Highways

del Castillo, Jose M.
Lovell, David J.
Carlos Daganzo
1995

This paper is concerned with technical investigations of traffic operations on automated highways. Estimates are made of the steady-state capacity of such freeways, paying particular attention to the effect of entry and exit maneuvers. The possibility of scheduling departing vehicles appropriately into platoons to minimize extraneous maneuvers is investigated. Characteristics of urban areas likely to be candidates for automated freeways are discussed, and some shortcomings of automated freeways, vis-à-vis conventional freeways, are pointed out. Finally, some areas of future research needs...

Effects of Queue Spillovers in Transportation Networks with a Route Choice

Carlos Daganzo
1996

Technical and Economic Viability of Automated Highway Systems: Preliminary Analysis

del Castillo, Jose M.
Lovell, David J.
Carlos Daganzo
1997

Technical and economic investigations of automated highway systems (AHS) are addressed. It has generally been accepted that such systems show potential to alleviate urban traffic congestion, so most of the AHS research has been focused instead on technical design and implementation issues. It is demonstrated that, despite making a number of assumptions that are favorable to AHS, the actual viable implementation opportunities for AHS are scarce, and that most existing congested urban areas can be disqualified on the basis of at least one criterion developed herein. Technical investigations...

A Simple Detection Scheme for Delay-Inducing Freeway Incidents

Lin, Wei-Hua
Carlos Daganzo
1997

This paper describes a freeway incident detection scheme that does not rely on complicated theories. The procedure compares the occupancy information recorded by two neighboring loop detectors to determine whether an incident has occurred in the intervening segment, using a recipe that is directly related to an intrinsic property of delay-inducing incidents. The method, which can also signal the termination of a detected incident, assumes that any significant bottlenecks are located outside the segment in question: i.e. that the segment is “homogeneous”. Independent of complicated theories...

The Netcell Simulation Package: Technical Description

Cayford, Randall
Lin, Wei-Hua
Carlos Daganzo
1997

This report describes the NETCELL simulation package. NETCELL is a freeway network simulation program based on the cell transmission model which captures the dynamic evolution of multicommodity traffic over a freeway network with three-legged junctions in a way that is consistent with the hydrodynamic theory of highway traffic. NETVIEW is a graphical postprocessor for viewing NETCELL output files. This document discusses implementation of the programs in detail, including the cell representation for a freeway network with three-legged junctions, data and file structures, inputs and outputs...

Determining the Spatial and Temporal Extents of a Queue Upstream of a Bottleneck

Carlos Daganzo
Lovell, David J.
Lawson, Timothy
1996

A simple approach is presented for modifying an input-output (or queueing) diagram to measure the time and distance spent by vehicles in a queue. The fundamental diagram and input-output diagrams are described. The extent of queues in time and space also is described.

Using Input-Output Diagram to Determine Spatial and Temporal Extents of a Queue Upstream of a Bottleneck

Lawson, Tim W.
Lovell, David J.
Carlos Daganzo
1997

A simple approach is described for modifying an input-output (or queue-ing) diagram to measure the time and distance spent by vehicles in a queue in a much simpler and self-serving manner than a time-space diagram. The graphic technique requires construction of a curve depicting the cumulative number of vehicles to have reached the back of the queue as a function of time, but, as indicated here, the technique can be easily automated with a spreadsheet. The technique is applied to the simple case of a constant departure rate from a bottleneck and to the slightly more general case of a...