Developing Updated Minimum In-Service Retroreflectivity Levels for Traffic Signs

Carlson, Paul J; Hawkins, H G; Schertz, Greg; Mace, D J; Opiela, Kenneth S

doi:10.3141/1824-15

Cited by 24 publications

(24 citation statements)

References 7 publications

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“…Materials of Classes I and II use spherical or prismatic retroreflective sheeting, while materials of Class III use exclusively prismatic retroreflective sheeting. Scientific studies have proven that materials with prismatic retroreflective sheeting have significantly better performance when it comes to visibility [5,6,7,8].…”

Section: Introductionmentioning

confidence: 99%

Model for Predicting Traffic Signs Functional Service Life – The Republic of Croatia Case Study

Babić

Macura

2017

PROMET

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Section: Introductionmentioning

confidence: 99%

Model for Predicting Traffic Signs Functional Service Life – The Republic of Croatia Case Study

Babić

Macura

2017

PROMET

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“…Such an outdoor test stand could be constructed very economically because the size the samples would probably be constructed from small scraps of material too small to use on an ordinary sign. (Carlson, 2003 Table B- as the cycle is shortened. However, if the current cycle can be extended then the state will be able to save money over the current sign replacement cycle.…”

Section: Methodsmentioning

confidence: 99%

“…In a conference in August of 2002 the 4 to 1 white to red ratio requirement had been removed. As of the August 2002 preliminary minimums the ratio has been added back in but has been reduced to 3 to 1 (Carlson, 2003). The full report on why the ratio was reduced will not be available until sometime in early 2003.…”

Section: Proposed Retroreflectivity Minimumsmentioning

confidence: 99%

Sign Retroreflectivity Study

Bischoff¹,

Bullock²

2002

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x ACKNOWLEDGMENTSWe would like to acknowledge the following people who served on the SAC committee for this project:• Gary Bowser -Indiana Department of Transportation We would also like to thank the people from 3M who lent us their 820 retroreflectometer for use in comparing the 820 to the ART 920 as well as comparing signs that failed the proposed minimums and/or 4 to 1 ratio.In addition we would like to thank the following students for their help and participation in the data collection for this study: John Beha, Matt DeVille, Kevin Lee, Jeff Martinkia, Andrew Nichols, Luke Nuber, and Siddarth Shankar. JTRP-2002/22, SPR-2482 Final Report Sign Retroreflectivity Study IntroductionSigning is a big yearly cost to state DOT's in sign maintenance and replacement costs. In 2001 the Indiana Department of Transportation (INDOT) replaced 14,930 signs at a cost of $1,067,931 and did maintenance work on 34,084 signs at a cost of $2,136,076. These values include the cost of the material used for making the sign, equipment use, and labor costs. Replacement is defined as a sign being replaced because it is ten years of age or older. Maintenance is defined as signs needing to be cleaned or replaced due to knockdowns or vandalism. Currently the replacement of interstate and highway signs, which are ten years or older, is about one-third of the entire cost of the INDOT sign maintenance and replacement program.Recently, guidelines have been proposed by the Federal Highway Administration (FHWA) for minimum retroreflectivity of traffic signs for state, county, and city roads in the United States. The purpose of this study was to evaluate if the majority of the signs currently by INDOT will meet the new minimum requirements proposed by the FHWA. In addition, this study provides quantitative data to assess the effectiveness of the current sign replacement program used by the Indiana Department of Transportation (INDOT) and determine if the current ten year replacement schedule is adequate to keep the State of Indiana in compliance with the new guidelines or if adjustments need to be made. This study was limited to ASTM Type III sheeting. FindingsGiven the data analysis performed on the data collected from the field the vast majority of the signs are expected to meet the proposed retroreflectivity minimums with no change in the current 10 year replacement policy. Only a very small percentage of the sample taken violated the most conservative minimums for each of the color categories. Over 98% of the signs in the field under normal circumstances should not only meet but exceed the proposed retroreflectivity minimums for any speed or size sign (Table 1).Currently, the proposed minimums are different requirements for different size and speeds for each color group. We have found that this needlessly complicates field inspection because the majority of the signs pass the most conservative minimums for each of the color groups.The majority of the signs with red backgrounds and white legends will meet the proposed white to red ratio req...

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“…Signs are weathered facing southward and angled 45° from the horizontal (AASHTO 2005b). AASHTO believes that this doubles the sign deterioration rate, such that three years in an AASHTO test deck is equivalent to six years in the field (Carlson and Hawkins 2003). A plot of retroreflectivity versus age for the NTPEP 2002-2005 data for 3M™ High Intensity (Type III) white sheeting is shown in Figure 1 for the Flagstaff, Arizona (AZ) and Wilmington, NC testing locations (AASHTO 2006).…”

Section: Fhwamentioning

confidence: 99%

“…Although the 2000 edition of the MUTCD did not include retroreflectivity guidelines, Section 2A.09 of the MUTCD was reserved for their future addition. Revised standards were proposed by an FHWA contractor in 2003 (Carlson and Hawkins 2003) and included in Revision 2 of the 2003 edition of the MUTCD effective January 2008 (FHWA 2007). Now that these new standards have been adopted, both compliance (for the safety and well-being of the public) and proof of compliance (to protect against lawsuits) are necessary.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Sign Deterioration Rates across the United States

et al. 2009

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In response to minimum retroreflectivity standards, transportation departments are implementing sign asset management strategies, which rely upon knowledge of how retroreflectivity decreases as signs weather and age. To provide this knowledge, the authors field-measured over 1000 inservice signs in scattered North Carolina Department of Transportation (NCDOT) divisions, collecting age and retroreflectivity data for white, yellow, red, and green signs and for ASTM sheeting Types I and III. Data from this study and data from five similar US efforts were analyzed using regression to identify the best available deterioration rate estimates, finding that retroreflectivity minimums are usually reached 8 to 15 years after installation.Initial results indicated that the best-fitting relationships between retroreflectivity and age were generally linear and that these models were significant despite having low R 2 values. Because age did not explain some of the variance, the authors re-evaluated their data including NCDOT divisions as a factor, finding that sign deterioration differed significantly by division, indicating that handling practices, manufacturing differences, and environmental exposure may be key deterioration model factors that merit future study.

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Developing Updated Minimum In-Service Retroreflectivity Levels for Traffic Signs

Cited by 24 publications

References 7 publications

Model for Predicting Traffic Signs Functional Service Life – The Republic of Croatia Case Study

Model for Predicting Traffic Signs Functional Service Life – The Republic of Croatia Case Study

Sign Retroreflectivity Study

Synthesis of Sign Deterioration Rates across the United States

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