Data

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.

Bounding the VRP Distance Before Knowing the Location of Points

Carlos Daganzo
1991

This note presents upper bounds for the minimum distance needed to visit n points in a unit circle, with a vehicle fleet based at its center and allowed to visit a maximum of q points per vehicle tour. The paper shows that the minimum distance can never exceed: [2n/q]+ + pi q. If points are randomly and uniformly distributed, and travel can only take place on a ring-radial network, the paper also proves that for q = 0(n**beta), 0 less than beta less than 1/2, the average minimum distance does not exceed: [4n/3q] + 0.82(pi n)**1/2 + 0(q). For the Euclidean metric, it is claimed that a...

Predictability of Time-Dependent Traffic Backups and Other Reproducible Traits in Experimental Highway Data

Smilowitz, Karen
Carlos Daganzo
1999

Traffic data from a 4-mile long congested rural road in Orinda, California, are used to show that traffic delays and vehicle accumulations between any two generic observers located inside a road section can be predicted from the traffic counts measured at the extremes of the section. The traffic model does not require "recalibration" on the day of the experiment, and works well despite what appears to be location-specific driver behavior.

Asymptotic Approximations for the Transportation LP and Other Scalable Network Problems

Carlos Daganzo
Smilowitz, Karen R.
2000

Network optimization problems with a "scalable" structure are examined in this report. Scalable networks are embedded in a normed space and must belong to a closed family under certain transformations of size (number of nodes) and scale (dimension of the norm). The transportation problem of linear programming (TLP) with randomly distributed points and random demands, the earthwork minimization problem of highway design, and the distribution of currents in an electric grid are examples of scalable network problems. Asymptotic formulas for the optimum cost are developed for the case where...

In Traffic Flow, Cellular Automata = Kinematic Waves

Carlos Daganzo
2004

This paper proves that the vehicle trajectories predicted by (i) a simple linear carfollowing model, CF(L), (ii) the kinematic wave model with a triangular fundamental diagram, KW(T), and (iii) two cellular automata models CA(L) and CA(M) match everywhere to within a tolerance comparable with a single "jam spacing". Thus, CF(L) = KW(T) = CA(L,M).

Discretization and Validation of the Continuum Approximation Scheme for Terminal System Design

Ouyang, Yanfeng
Carlos Daganzo
2006

This paper proposes an algorithm that automatically translates the “continuum approximation” (CA) recipes for location problems into discrete designs. It applies to terminal systems, but can also be used for other logistics problems. The study also systematically compares the logistics costs predicted by the CA approach with the actual costs for discrete designs obtained with the automated procedure. The predictions are quite accurate. The paper also gives conditions under which the discrete solution has a small optimality gap.

Experimental Investigation of Urban‐Scale Macroscopic Fundamental Diagrams

Carlos Daganzo
2008

Existence of Urban-Scale Macroscopic Fundamental Diagrams: Some Experimental Findings

Geroliminis, Nikolaos
Carlos Daganzo
2008

A field experiment in Yokohama (Japan) reveals that a macroscopic fundamental diagram (MFD) linking space-mean flow, density and speed exists on a large urban area. The experiment used a combination of fixed detectors and floating vehicle probes as sensors. It was observed that when the somewhat chaotic scatter-plots of speed vs. density from individual fixed detectors were aggregated the scatter nearly disappeared and points grouped neatly along a smoothly declining curve. This evidence suggests, but does not prove, that an MFD exists for the complete network because the fixed detectors...

Robust Tests for the Bullwhip Effect in Supply Chains with Stochastic Dynamics

Ouyang, Yanfeng
Carlos Daganzo
2016

This paper analyzes the bullwhip effect in single-echelon supply chains driven by arbitrary customer demands and operated nondeterministically. The supply chain, with stochastic system parameters, is modeled as a Markovian jump linear system. The paper presents robust analytical conditions to diagnose the bullwhip effect and bound its magnitude. The tests are independent of the customer demand. Examples are given. Ordering policies that pass these tests, and thus avoid the bullwhip effect in random environments for arbitrary customer demands, are shown to exist. The paper also presents...

The Minuet Method: A Summary

Carlos Daganzo
2019

This brief note shows how to solve Sudoku puzzles by hand. It is targeted to the Sudoku player who can solve intermediate and hard puzzles but sometimes fails on the extremely difficult.