Although specialized equipment and vehicles make up a large portion of state transportation budgets, an OTREC research report found little consistency in how states decide to replace this equipment.

Researchers David Kim and David Porter of Oregon State University surveyed 25 state departments of transportation to determine how they made replacement decisions. Nearly all consider the age of the vehicle or piece of equipment, with many considering how much use it gets.

Around half use thresholds, such as number of miles or months in service, to identify candidates for replacement. Some consider the equipment’s repair cost or operating cost, while others rely on physical inspections. None explicitly considers greenhouse gas emissions or other environmental concerns in its replacement criteria.

Given the huge range of approaches, Kim and Porter wondered if modeling could lead to better decision-making. They ran various models against the simple approach of using equipment age as a threshold value.

As it turns out, the simple approach isn’t too bad. In fact, it does better than one complicated mathematical model and about the same as a second model.

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OTREC students and faculty were active participants in the 15th World Congress on Intelligent Transportation Systems, held in New York City, November 16-20, 2008. Lisa Diercksen, an MS student at PSU presented “A Second Look at the Effectiveness of the Myrtle Creek Dynamic Advanced Curve Warning System;” Jerzy Wieczorek, an MS student in Statistics at PSU presented “Using Archived ITS Data to Automatically Identify Freeway Bottlenecks in Portland, Oregon;” Rafael J. Fernandez-Moctezuma, a Ph.D. student in computer science at PSU presented “Developing an Imputation Strategy for an Archived Data User Service in Portland, Oregon;” Galen McGill of the Oregon Department of Transportation presented “Accuracy in Real-Time Estimation of Travel Time,” co-authored with PSU Prof. Kristin Tufte. Prof. Robert Bertini of PSU also presented: “Empirical Evaluation of Adaptive Ramp Metering Along Two Freeway Corridors in Portland, Oregon;” and “Toward Transport Payment Integration in Portland, Oregon.” Prof. David Porter and Prof. David Kim, of the OSU Department of Industrial and Manufacturing Engineering also attended the Congress. The World Congress is sponsored by ITS AMerica, ERTICO-ITS Europe and ITS Japan.