Modeling

Wildfire Evacuation Planning Can Be Greatly Enhanced by Considering Fire Progression, Communication Systems, and Other Dynamic Factors

Soga, Kenichi, PhD
Comfort, Louise, PhD
Zhao, Bingyu, PhD
Lorusso, Paola, MSc
Soysal, sena
2021

Wildfires have become a perpetual crisis for communities across California. For life-threatening wildfires, mass evacuation often becomes the only viable option to protect lives. Yet, looking back at recent events, including the devastating 2018 Camp Fire in Northern California, there are significant challenges associated with the evacuation process, such as multi-agency coordination, agency-resident communication, and management of extraordinarily high amounts of traffic within a short period of time. Currently, emergency planners use evacuation models that are typically based on existing...

Some Properties of a Multi-Lane Extension of the Kinematic Wave Model

Laval, Jorge A.
2003

This paper extends an existing continuum multi-lane formulation for traffic flow, provides a discrete formulation for its numerical solution, and show initial results. The new formulation enables a natural treatment of boundary conditions such as merges, diverges, lane-drops and moving bottlenecks. The proposed model needs few extra parameters and is parsimonious. The look-ahead distance, for example, induces that non-local conditions affect the flow at any time-space point, causing smooth regime changes and fast waves. We find that as the look-ahead distance tends to zero, the solution...

Achieving a Higher Capacity National Airspace System: An Analysis of the Virtual Airspace Modeling and Simulation Project

Smirti, Megan
Hansen, Mark
2009

The Virtual Airspace Modeling and Simulation (VAMS) project developed by the National Aeronautics and Space Administration (NASA) presents a detailed plan for increasing National Airspace System capacity. Interviews with aviation experts regarding the VAMS project led to lessons learned which can inform current modernization plans and processes, as the current system prepares for modernization. According to experts consulted, development should include a small number of project developers who provide periodic opportunities for wide stakeholder feedback; roadmaps should incorporate...

Asymptotic Approximations for the Transportation LP and Other Scalable Network Problems

Daganzo, Carlos F.
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...

The Ethical Challenges and Professional Responses of Travel Demand Forecasters

Brinkman, Anthony P.
2003

Thirty years ago scholars first presented convincing evidence that local officials use biased travel demand forecasts to justify decisions based on unstated considerations. Since then, a number of researchers have demonstrated convincingly that such forecasts are systematically optimistic-often wildly so-for reasons that cannot be explained solely by the inherent difficulty of predicting the future. Why do modelers-professional engineers and planners who use quantitative techniques to predict future demand for travel and estimate its potential impact on built and proposed transportation...

An Analysis of Port Selection

Malchow, Matthew Brian
2001

The objective of this research is to study the competition among ports. In particular we study the relation between port characteristics and port market share of maritime traffic. Maritime carriers make two primary decisions that affect ports. In the long-term, they assign vessels to routes. In the short-term, they assign each shipment to a vessel and, with that vessel, a port. In this research, we assume that vessel schedules are fixed and model the assignment of shipments as a function of the attributes that describe each port. For a carrier, some assignments are simpler than other...

Dynamic Stochastic Optimization Models for Air Traffic Flow Management

Mukherjee, Avijit
2004

This dissertation presents dynamic stochastic optimization models for Air Traffic Flow Management (ATFM) that enables decisions to adapt to new information on evolving capacities of National Airspace System (NAS) resources. Uncertainty is represented by a set of capacity scenarios, each depicting a particular time-varying capacity profile of NAS resources. We use the concept of a scenario tree in which multiple scenarios are possible initially. Scenarios are eliminated as possibilities in a succession of branching points, until the specific scenario that will be realized on a particular...

Optimal Infrastructure System Maintenance and Repair Policies with Random Deterioration Model Parameters

Park, Sejung
2004

Accurate facility deterioration models are important inputs for the selection of Infrastructure Maintenance, Repair, and Reconstruction (MR & R) policies. Deterioration models are developed based on expert judgment or empirical observations. These resources, however, might not be sufficient to accurately represent the performance of infrastructure facilities. Incorrect deterioration models may lead to wrong predictions of infrastructure performance and selection of inappropriate MR & R policies. This results in higher lifecycle costs. Existing infrastructure MR & R...

Space Syntax: An Innovative Pedestrian Volume Modeling Tool for Pedestrian Safety

Raford, Noah
Ragland, David R.
2003

This paper describes an innovative pedestrian modeling technique known as Space Syntax, which was used to create estimates of pedestrian volumes for the city of Oakland, California. These estimates were used to calculate pedestrian exposure rates and to create a Relative Risk Index for the city’s first pedestrian master plan. A major challenge facing planners, transportation engineers, and pedestrian-safety advocates is the lack of detailed and high quality pedestrian-exposure data. Exposure is defined as the rate of contact with a potentially harmful agent or event. Pedestrian exposure is...

Pedestrian Volume Modeling for Traffic Safety and Exposure Analysis: The Case of Boston, Massachusetts

Raford, Noah
Ragland, David
2006

This paper examines three types of pedestrian volume models in light of their usefulness for estimating pedestrian exposure for pedestrian safety research. The need for pedestrian flow data as part of pedestrian exposure and safety analysis is outlined, and the background of each type of model is discussed. It then selects the space syntax network analysis model to estimate pedestrian volumes for the city of Boston, Massachusetts. It was found that the model was able to accurately predict pedestrian flows (r-squared 0.81, p-value < 0.0001) after incorporating distance to transit...