ITS Berkeley

Physical Distribution from a Warehouse: Vehicle Coverage and Inventory Levels

Carlos Daganzo
Newell, Gordon F.
1985

This paper studies the costs involved in distributing items from a warehouse or depot to randomly scattered customers on a day-to-day basis. Two trade-offs are explored simultaneously. The first one arises because by accumulating large inventories at the depot it is possible to build more efficient distribution tours. This trade-off has already been explored for both distribution of goods (Burns et al., 1983) and passengers (Daganzo et al., 1977; Hendrickson, 1978). Another tradeoff, which involves the length of individual vehicle tours (Clarens and Hurdle, 1975), balances the inventory...

The Uniqueness of a Time-Dependent Equilibrium Distribution of Arrivals at a Single Bottleneck

Carlos Daganzo
1985

Motorists going through a bottleneck during the morning rush hour have to time their departure times to ensure they arrive to work at a reasonable time. Traffic and congestion levels at the bottleneck depend on the motorists' work schedule and the disutility of unpunctuality. This paper shows that, under certain conditions, there is only one equilibrium order of arrivals; an order under which motorists do not have an incentive to jockey for position in the queue.

Configuration of Physical Distribution Networks

Carlos Daganzo
Newell, Gordon F.
1986

Distribution problems, including vehicle routing and warehouse location problems, are usually formulated by considering a finite number of possible locations for the customers, the warehouses, and vehicle stops. The question of selecting which of these points are actually used (and how) is a mixed-integer programming problem which is difficult to solve. Thus, such a discrete formulation results in a problem that has to be solved heuristically; it also entails a large data preparation effort each time a solution has to be developed in response to changing world conditions. The continuous...

Extrapolating Automobile Usage Data to Long Time Periods

Horowitz, Abraham D.
Carlos Daganzo
1986

This study illustrates a statistical procedure that can be used to estimate the fraction of a given population experiencing a “rare” event during a long time period, given a few days of observation. In an automobile usage context, the rare event could be the occurrence of an automobile occupancy of four or more persons and/or a travel distance of 100 miles or more on any given day. The technique, which can be important for the design of durable goods, is illustrated with four numerical examples.

Distributing Nonstorable Items Without Transshipments

Han, Anthony F. W.
Carlos Daganzo
1986

The research reported in this paper attempted to find optimal strategies for distributing items from one depot to many demand points without transshipments and within a limited amount of time. The objective was to find a near optimal partition of the region supplied by the depot into districts (the zones containing the points visited by one delivery route) and corresponding shipment sizes and costs. Initially, the average distribution cost per demand point on a single delivery route was studied using expressions that relate route length to the dimensions of a delivery district. Two...

Static Blocking at Railyards: Sorting Implications and Track Requirements

Carlos Daganzo
1986

In this paper, various strategies for minimizing the amount of switching done at a classification yard are examined. We investigate how the allocation of blocks (the sorting classes recognized at the yard) to classification tracks affects switching work. Given are the sorting classes, as well as the schedule and block makeup of the departing trains. Only static strategies are considered—strategies where every block has been assigned permanently to a classification track. Simple formulas are given for the minimum number of tracks needed to implement a strategy, and for the amount of...

Design of Multiple Vehicle Delivery Tours—II Other Metrics

Newell, Gordon F.
Carlos Daganzo
1986

The methods described in Part I for a ring-radial metric are generalized to a network having a fine nearly rectangular grid of local roads, but possibly with a few fast roads superimposed. To select delivery zones, one should first draw the equi-travel-time contours from the source and then choose nearly rectangular zones with suitable width and orientation relative to the network grid and the local contour lines. Some illustrations are given for an idealized square grid of roads. In this case the rectangular delivery zones should be oriented at 45° to the grid, perpendicular to the...

Assembly Line Job Sequencing Principles

Burns, Lawrence D.
Carlos Daganzo
1987

Assembly line job sequencing establishes the order in which jobs are processed by an assembly line. This research focuses on job sequencing methods for assembly lines with work stations that receive the same fixed job sequence, are coupled together so that there is no work-in-process storage, and are balanced so that jobs move continuously between them at a constant rate. Automobile assembly lines frequently have these characteristics. Simple analytical principles are derived that aid in evaluating trade-offs between different job sequencing objectives. Included are set-up cost objectives...

A Graphical Method for Optimizing a Continuous Review Inventory System

Horowitz, Abraham D
Carlos Daganzo
1986

Design of Multiple-Vehicle Delivery Tours—I A Ring-Radial Network

Newell, Gordon F.
Carlos Daganzo
1986

Certain aspects of what is commonly described as the “Vehicle Routing Problem” are discussed. We wish to deliver items to a large number of points randomly distributed over some region by means of vehicles, each of which can deliver to only C points. The key to any detailed routing to minimize the cost of delivery (by hand or computer) is first to partition the region into zones in which individual vehicles make deliveries. We assume here that there are many such zones, an average density of points δ, that the “unit of length” δ-1/2 is large compared with the spacing between roads, and C...