NETS News

Vol II, Issue 11 November 2006

Genetic Algorithm Optimization Enhancements Made by NaSS Team Members
Navigation System Simulation Model (NaSS) researchers Dr. Shiaaulir Wang and Professor Paul Schonfeld, both of the University of Maryland, recently completed further enhancements to the genetic algorithm (GA) optimization process. Their report provides a promising demonstration of simulation-based optimization and analyzes the search efficiency and solution quality obtained with the proposed genetic algorithm. In dealing with project selection and scheduling problems, the optimization process can now consider additional constraints, such as project precedence and regional budget constraints. A prescreening process is used to accelerate the search by avoiding the evaluation through simulation of solutions that violate constraints or duplicate previously evaluated solutions. The performances of various GA operators are also compared with a simplified evaluation model.

Fact Sheet |  Report

Regional Routing Model Meeting
On September 28, 2006, Corps economists, academics and Federal economic and transportation specialists met in Washington D.C. to discuss the Regional Routing Model (RRM). The meeting covered the technical nature of the RRM development and investigated integration with other related work that will benefit the RRM's economic framework. Work on the Regional Routing Model to date was reviewed, including the development of a database of wheat transportation and the potential application of solving mode and route choice questions as related to specific infrastructure questions. The session also discussed the National accounts being developed by the U.S. Department of Agricultural, Economic Research Service, with the potential to link national freight models with national economic account studies. The meeting highlighted some additional areas of research by the Regional Routing team to identify GIS and data processing tools, such as training and user manuals, to access the information.

Fact Sheet |  Presentation by Frank Southworth

Spatially Generated Demands Paper Accepted for Publication
The work of Professors Kenneth Train and Wesley W. Wilson on "Spatially Generated Demands" has been accepted for publication in Research in Transportation Economics: Railroad Economics. This is a series volume edited by Wayne Talley of Old Dominion University and Scott Dennis of the Surface Transportation Board. The annual series is published by Elsevier and should be available in 2007.

This research develops and estimates a mode choice model for spatially differentiated shippers who choose between rail and barge where trucks provide access to the two modes (if needed). Their results are then used along with auxiliary regressions to illustrate how the mode choices can be directly aggregated to a pool or a port level. It further illustrates how market areas for modes are determined by spatial locations of the shippers and the locations of infrastructure. Drafts of this research are available on:

Fact Sheet | Paper

NETS Team Meets with Hong Kong Researchers
Keith Hofseth, Director of the NETS program, and IPA Wesley Wilson from the University of Oregon met with representatives of the Global Taskforce for Port Benchmarking on November 9, 2006. These representatives, Professors John Liu and Jia Yan from the International Center for Maritime Studies (http://www.icms.polyu.edu.hk/) at Hong Kong Polytechnic University are spearheading a research effort designed to uncover the efficiency of Ports and, in particular, the efficiency of container terminal operating companies. The purpose of the meeting was to share information on related research agendas with an eye toward forming longer term research alliances.

Fact Sheet

Port Efficiency and Trade Flows Paper Updated
The updated Port Efficiency and Trade Flows includes a new section of analysis that uses a gravity trade model of international trade flows to estimate the effort of port efficiency measures on these flows. Because the port-efficiency measures are time-varying, they can be controlled for unobserved country-level heterogeneity in the gravity trade model using country-level fixed effects. The updated paper and the researchers' responses to the referee's comments have been issued as NETS Report 06-NETS-R-11 and published on the NETS Bookshelf.

Fact Sheet | Report

TRB Conference Featured NETS Team Members
On September 25-27, 2006, the Transportation Research Board hosted a conference on freight demand modeling and the role of analytical tools to describe and predict transportation impacts. The conference focused primarily on understanding the data and analysis for freight movements by focusing on identifying the "State of the Practice", Emerging Techniques, and to outline possible strategies for future analytical and data developments. Several NETS team members participated in the sessions. Keith Hofseth and Bruce Lambert served as session moderators. Frank Southworth spoke on future data modeling efforts, which included an outline on the NETS program. Bruce Lambert spoke on the Federal need to understand freight data and to act on that information to improve freight mobility. The Conference program and most the presentations are available at the TRB website You are leaving a Federal Government web site. Click this icon for more information..


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Navigation Economic Technologies Program, US Army Corps of Engineers