Data

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.

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.

Minuet: A Method to Solve Sudoku Puzzles by Hand

Carlos Daganzo
2018

This paper presents a systematic method to solve difficult 9 x 9 Sudoku puzzles by hand. While computer algorithms exist to solve these puzzles, these algorithms are not good for human's to use because they involve too many steps and require too much memory. For humans, all one can find in the literature are individual tricks, which used together in ad hoc ways can be used to solve some puzzles--but not all. To the author's knowledge, a systematic procedure made up of well-defined steps that can be carried out by hand and solve all puzzles has not been devised. This paper proposes one such...

Bayesian Estimation of Origin and Destination from Masked Trip Data

Yeo, Yuneil
Niu, Chenming
Maria Laura Delle Monache
2024

This article introduces a statistical method to estimate trips origin and destination locations from a masked trip data set. The estimation method uses trip features, the graph of the network, and publicly accessible external information on the realtime congestion status to find the most probable trips origin and destination based on a Bayesian approach, Markov Chain rule, and rank aggregation method. A case study of Porto, Portugal assesses the performance of the statistical estimation method by comparing the estimated location with the centroids of reported locations and with the actual...

Enabling Analysis and Visualization of Transportation Big Data

Rees, Stephen
Sprinkle, Jonathan
Wang, Xia
Bunting, Matthew
Work, Daniel B.
Lee, Jonathan W.
Maria Laura Delle Monache
Alexandre Bayen
Piccoli, Benedetto
2025

Transportation studies generate massive amounts of data that are difficult to store, process, query and visualize quickly and easily. Overcoming these challenges are an essential aspect of making the collected data useful to both the original study and other research that could build on the results. We explore the impact of database implementation, specifically IoTDB, on these aspects of data management with respect to transportation on existing datasets.

(U)NFV: Supervised and Unsupervised Neural Finite Volume Methods for Solving Hyperbolic PDEs

Lichtle, Nathan
Canesse, Alexi
Fu, Zhe
Matin, Hossein Nick Zinat
Maria Laura Delle Monache
Alexandre Bayen
2025

We introduce (U)NFV, a modular neural network architecture that generalizes classical finite volume (FV) methods for solving hyperbolic conservation laws. Hyperbolic partial differential equations (PDEs) are challenging to solve, particularly conservation laws whose physically relevant solutions contain shocks and discontinuities. FV methods are widely used for their mathematical properties: convergence to entropy solutions, flow conservation, or total variation diminishing, but often lack accuracy and flexibility in complex settings. Neural Finite Volume addresses these limitations by...

Benefit Evaluation of Crash Avoidance Systems

Godbole, Datta N.
Raja Sengupta
Misener, James
Kourjanskaia, Natasha
Michael, James B.
1998

A five-layer hierarchy to integrate models, data, and tools is proposed for benefits assessment and requirements development for crash avoidance systems. The framework is known as HARTCAS: Hierarchical Assessment and Requirements Tools for Crash Avoidance Systems. The analysis problem is multifaceted and large-scale. The driving environment is diverse and uncertain, driver behavior and performance are not uniform, and the range of applicable collision avoidance technologies is wide. Considerable real-world data are becoming available on certain aspects of this environment, although the...