ITS Berkeley

Technical Note—Two Properties of the Nested Logit Model

Daganzo, Carlos F.
Kusnic, Michael
1993

This paper presents simple formulae for the utility covariances of the nested logit (NL) model, and based on these defines a “scaled tree” that can be used as an aid for the interpretation of estimation results. The paper also shows that the full information log-likelihood function of linear-in-the-parameters NL models is concave in the utility parameters. Thus, conditional on the scaling parameters, full information maximum likelihood (FIML) searches cannot get trapped in local maxima.

Effect of Modeling Assumptions on Evolution of Queues in a Single Corridor

Daganzo, Carlos F.
Lin, Wei-Hua
1994

A qualitative description is presented of queuing patterns under an idealized scenario analogous to the evolution of traffic congestion during the morning peak hour in a long corridor leading to a single destination. The simplicity of the scenario allows the results to be verified independently by hand. Initially the corridor is assumed to consist of a single freeway. Traffic is generated at the freeway's many on-ramps during a short period and then is assumed to subside. Capacity limitations create queues on the ramps and the freeway, whose evolution is then described. A special...

Technical Description of NETCELL: General Framework and Data Structure

Lin, Wei-Hua
Daganzo, Carlos F.
1994

This technical note presents a prototype of a freeway network simulation program, NETCELL, currently under development. NETCELL is 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. The report discusses implementation of the prototype program in detail, including cell representation for a freeway network with three- legged junctions data and file structures, inputs and outputs, and some key algorithms...

Assembly System Design Principles and Tradeoffs

Daganzo, Carlos F.
Blumenfeld, D.E.
1994

This paper develops an analytical model to evaluate serial and parallel designs for an assembly system. The purpose is to identify when each design is cost-effective, using minimal data. The analysis shows that the design alternatives are based on a trade-off between labour and equipment utilization. Equations are derived for a simple system to illustrate this trade-off. Results indicate that the optimal trade-off depends simply on the ratio of labour to equipment costs. The trade-off analysis provides a first step towards establishing basic principles for assembly system design.

The Cell Transmission Model: A Dynamic Representation of Highway Traffic Consistent with the Hydrodynamic Theory

Daganzo, Carlos F.
1994

This paper presents a simple representation of traffic on a highway with a single entrance and exit. The representation can be used to predict traffic's evolution over time and space, including transient phenomena such as the building, propagation, and dissipation of queues. The easy-to-solve difference equations used to predict traffic's evolution are shown to be the discrete analog of the differential equations arising from a special case of the hydrodynamic model of traffic flow. The proposed method automatically generates appropriate changes in density at locations where the...

A Continuum Theory of Traffic Dynamics for Freeways with Special Lanes

Daganzo, Carlos F.
1995

This paper presents a generalized theory of kinematic waves for freeways with two vehicle types and a set of lanes reserved for one of the vehicle classes. The theory is not restricted to freeways on which the special lanes are clearly identified by signs and pavement markings; e.g. for high occupancy vehicles. It may also apply if the restrictions are self-imposed, such as would occur on a freeway segment upstream of a busy off-ramp where the existing traffic naturally avoids the ‘far-side’ lanes. Of particular interest are oversaturated time periods because the original theory of...

An Informal Introduction to Transportation and Traffic Operations

Daganzo, Carlos F.
1995

The Nature of Freeway Gridlock and How to Prevent it

Daganzo, Carlos F.
1995

Evaluation of Alternative AHS System Operating Concepts

Daganzo, Carlos F.
Cayford, Randall
Lin, Wei-Hua
1995

This paper focuses on technical and economic investigations of automated highway systems (AHS). It attempts to show that the actual viable implementation opportunities for AHS are scarce. The paper begins with an investigation that looks at realistic estimates of AHS capacity, interfacing with the local street system, and storage issues. The authors then identify criteria to help in determining which types of urban areas might be potential candidates for AHS technologies. Certain locations where AHS might be beneficial are identified, but doubt is raised regarding the extent of the...

A Pareto Optimum Congestion Reduction Scheme

Daganzo, Carlos F.
1995

This article shows that certain congestion reduction schemes have the potential for not penalizing anyone. The traditional social welfare approach is modified to address the distribution of gains and losses across the population. As a first step in this line of research, we consider a transportation system where congestion delay is simply given by a function of its user flow. We show that a particular pricing scheme with variable tolls, that can be viewed as hybrid between rationing and pricing, can benefit everyone (unlike pure pricing alone) even if the collected revenues are not...