ITS Berkeley

Multi-Lane Hybrid Traffic Flow Model: Quantifying the Impacts of Lane-Changing Maneuvers on Traffic Flow

Laval, Jorge A.
Daganzo, Carlos F.
2004

A multi-lane traffic flow model realistically captures the disruptive effects of lane- changing vehicles by recognizing their limited ability to accelerate. While they accelerate, these vehicles create voids in the traffic stream that affect its character. Bounded acceleration explains two features of freeway traffic streams: the capacity drop of freeway bottlenecks, and the quantitative relation between the discharge rate of moving bottlenecks and bottleneck speed. The model com- bines a multilane kinematic wave module for the traffic stream, with a detailed constrained-motion model to...

On the Stability of Supply Chains

Daganzo, Carlos F.
2004

This paper examines the stability of decentralized, multistage supply chains under arbitrary demand conditions. It looks for intrinsic properties of the inventory replenishment policies that hold for all customer demand processes and for policies with desirable properties. It is found that the overall conditions experienced by suppliers several stages removed from the final customer, e.g., the variances of the orders they receive and the inventories they keep, depend on the policy much more than on the demand process. A policy-specific but demand-independent upper bound for the order...

Logistics Systems Analysis

Daganzo, Carlos F.
2005

This expanded edition of A Logistics Systems Analysis@ includes new - search results and numerous modifications to enhance comprehensiveness and clarity. It has two new sections, a new appendix, and more than half a dozen new figures. A few references have also been added, but the bibli- raphy is not exhaustive. Much of the new material is based on work by Profs. Alan Erera (Georgia Tech), Karen Smilowitz (Northwestern U. ), and by PhD candidate Yanfeng Ouyang (U. C. Berkeley). Their help is gratefully acknowledged. The financial support of the National Science Foundation and the...

On the Numerical Treatment of Moving Bottlenecks

Daganzo, Carlos F.
Laval, Jorge A.
2005

This paper shows how moving obstructions in (kinematic wave) traffic streams can be modeled with “off-the shelf” computer programs. It shows that if a moving obstruction is replaced by a sequence of fixed obstructions at nearby locations with the same “capacity”, then the error in vehicle number converges uniformly to zero as the maximum separation between the moving and fixed bottlenecks is reduced. This result implies that average flows, densities, accumulations and delays can be predicted as accurately as desired with this method. Thus, any convergent finite difference scheme can be...

A Variational Formulation of Kinematic Waves: Basic Theory and Complex Boundary Conditions

Daganzo, Carlos F.
2005

This paper proves that the solution of every well-posed kinematic wave (KW) traffic problem with a concave flow-density relation is a set of least-cost (shortest) paths in space-time with a special metric. The equi-cost contours are the vehicle trajectories. If the flow-density relation is strictly concave the set of shortest paths is unique and matches the set of waves. Shocks, if they arise, are curves in the solution region where the shortest paths end. The new formulation extends the range of applications of kinematic wave theory and simplifies it considerably. For example, moving...

Crane Double Cycling in Container Ports: Affect on Ship Dwell Time

Goodchild, Anne V.
Daganzo, Carlos F.
2005

Loading ships as they are unloaded (double-cycling) can improve the efficiency of a quay crane and thus container port. This paper describes the double-cycling problem, and presents two solution algorithms and simple formulae to estimate reductions in the number of operations, and operating time. The problem is formulated as a scheduling problem. Small problems can be solved to optimality with a standard numerical solver, but problems of typical size are computationally burdensome and terminated after 10 hours with optimality gaps larger than 50%. A formula for an improved lower bound to...

Some Properties of Decentralized Supply Chains

Ouyang, Yanfeng
Daganzo, Carlos F.
2005

This paper analyzes the bullwhip effect in decentralized, linear and time-invariant (LTI) supply chains. It generalizes existing results by broadening the class of policies and customer demand processes under consideration. The supply chain is modeled as a single-input, singleoutput control system driven by arbitrary demands. The paper discusses the appropriateness of various metrics for the bullwhip effect, and derives analytical conditions to predict its presence independently of the demand process. The paper also gives a formula for the variance of the order stream at any stage when the...

Improving City Mobility Through Gridlock Control: An Approach and Some Ideas

Daganzo, Carlos F.
2005

This paper examines the effect of gridlock on urban mobility. It defines gridlock and shows how it can be modeled, monitored and controlled with parsimonious models that do not rely on detailed forecasts. The proposed approach to gridlock management should be most effective when based on real-time observation of relevant spatially aggregated measures of traffic performance. This is discussed in detail. The ideas in this paper suggest numerous avenues for research at the empirical and theoretical levels. An appendix summarizes some of these.

Bus Lanes with Intermittent Priority: Screening Formulae and an Evaluation

Eichler, Michael
Daganzo, Carlos F.
2005

This paper evaluates strategies for operating buses on signal-controlled arterials using special lanes that are made intermittently available to general traffic. The advantage of special bus lanes, intermittent or dedicated, is that they free buses from traffic interference; the disadvantage is that they disrupt traffic. We find that intermittent lanes, unlike dedicated ones, do not significantly reduce street capacity. Intermittence, however, increases the average traffic density at which the demand is served, and as a result increases traffic delay. These delays are more than offset by...

A Review of Green Logistics Schemes Used in Cities Around the World

Geroliminis, Nikolaos
Daganzo, Carlos F.
2005

Freight carriers strive to provide higher levels of transportation service with lower costs. However, the economic and environmental viability of cities are negatively affected by the present organization of urban goods distribution. Can these two competitive goals be harmonised to create efficient and environmentally friendly urban logistics systems? This paper presents several examples of “green logistics” schemes tried in a number of forward-looking cities around the world. The review highlights the basic qualitative ideas of these schemes and the results of field tests. Most of the...