Date of Award:

12-2012

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee Chair(s)

Kevin Heaslip

Committee

Kevin Heaslip

Committee

Anthony Chen

Committee

Paul J. Barr

Abstract

For a variety of reasons both within and outside the control of transportation agencies, there is a higher frequency of fatalities during nighttime hours than during daytime hours. In an effort to enhance visual cues for nighttime motorists, the Federal Highway Administration (FHWA) established the minimum maintained retroreflectivity levels. This retroreflective mandate required agencies or public officials that have jurisdiction over a traffic sign population to implement maintenance methods that would ensure signs were performing at or above the minimum levels. Retroreflectivity is a unique type of reflection that distinguishes itself by reflecting light back in the direction of the light source. The retroreflective process produces an illuminated sign, and the efficiency of this process is measured in candelas per lux per square meter (cd/lx/m2). While ensuring adequate brightness, via retroreflectivity, enables a sign to stand out from the surrounding environment, it does not guarantee message conveyance. In order for a message to be conveyed and provide for an adequate reaction time, traffic signs need to be highly visible and legible.

The Utah Department of Transportation (UDOT) initiated this research as a response to the retroreflectivity mandate. In order to take full advantage of this research, UDOT wanted to reevaluate how they manage their traffic sign assets. To evaluate the current performance and identify any current issues, a collection effort was launched. Analysis was conducted to determine the contributing factors to rapid sheeting deterioration and increased damage rates. With the knowledge from the collection effort and the analysis on traffic sign performance, the feasibility of the different FHWA methods is discussed.

This research will provide plan recommendations that are tailored to UDOT’s specific sign needs. These recommendations will allow UDOT to maintain compliance with the retroreflectivity mandate, while ensuring their traffic sign assets retain high visibility and legibility. By efficiently managing their traffic signs assets, UDOT can limit the financial and personnel strains of the retroreflectivity mandate, while improving motorist safety.

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Comments

This work made publicly available electronically on December 20, 2012.

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