Pavement Marking Durability

Presented By: Jennifer Vosburgh, EI 10/26/2005

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Research Overview and Objectives „

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Longitudinal pavement markings are the most widely implemented traffic control devices. Numerous types of materials are applied to roadways including thermoplastic, epoxy, and polyurea. Degradation is caused by environmental factors. Goals: „ To determine service life and overall cost of various markings in terms of degradation with consideration to durability, retroreflectivity, and cost. „ To develop recommendations for a pavement marking application and replacement strategy.

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Background „

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Pavement markings provide a visual reference that aid to position the car within the roadway. MUTCD 3A.02 – markings that must be visible at night, should be retroreflective unless ambient lighting assures that markings are adequately visible and consideration should be given to selecting pavement marking materials… Retroreflective materials are utilized during application to provide for nighttime visibility.

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Background, Cont. „

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“Retroreflectivity is the property to reflect light back towards its source.” - FHWA Spherical glass beads are embedded into the marking binder during installation. The binder contains pigments which scatter the light and allow more for light reflection.

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Background, Cont. „

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Over time, pavement markings degrade and become less reflective. Causes of degradation include: „ „ „ „ „ „

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Improper application. Wear by vehicles. Oxidation and ultraviolet sunlight. Fading pigments. Binder can become brittle creating holidays or bead release. Damage from winter maintenance practices.

Once markings no longer exhibit acceptable nighttime visibility, the markings should be replaced.

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Project Scope „ „

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Phase I: Literature Review. Phase II: Data compilation from existing projects. Phase III: Data Collection from new projects. Phase IV: Data Reduction/Interim Report Phase V: Economic Analysis of life cycle costs. Phase VI: An evaluation of the deterioration mechanisms of the performance factors. Phase VII: Final Report.

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Phase I: Literature Review „

To gain knowledge of testing procedures, current research, current operation practices and innovative technologies regarding pavement markings. Field Studies. „ Laboratory Studies. „ Sampling Procedures. „ Pavement Management Marking Systems (PMMS). „

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Data Collection (Phase II and III) „

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Marking Type: „ Thermoplastic (76%) „ Polyurea (20%) „ Epoxy (4%) „ Waterborne Paint „ Permanent Tape Site Location Selection: „ Roadway Classification „ Geographic Location „ AADT „ Age

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Data Collection (Phase II and III) „

Thermoplastic Markings (AASHTO M-249): „

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Homogenously composed of pigment, filler, resins (hydrocarbon or alkyd) and glass reflectorizing spheres. Thermoplastic resin – linear macromolecular structure that will repeatedly soften when heated and harden when cooled. „

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Hydrocarbon – petroleum derived resins (most frequently specified). Alkyd – naturally occurring resin that is resistant to petroleum products.

Subject to VTrans Standard Specifications 646.07(c) and 708.08.

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Data Collection (Phase II and III) „

Polyurea Markings: „

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Two part component, polyurea coating material with glass beads and possibly additional reflective elements. Chemical technology based on two component reacted materials: „ „ „

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Amine blend Isocyanate mixture Results in very rapid reactions which produce extended chain polymer structures generally in membranous form.

Subject to VTrans Specifications 646.07(modified) and 708.15.

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Data Collection (Phase II and III) „

Epoxy Markings: Two component (two parts resin to one part curing agent), epoxy materials with glass beads applied as it cures „ Epoxy resin – polyether resin formed originally by the polymerization of bisphenol A and epichlorohydrin, having high strength and low shrinkage during curing. „ Subject to VTrans Specifications 646.07(b) and 708.08(c). „

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Data Collection (Phase II and III) „

Glass Beads: Since 1997, crushed clear glass (max. size of 33 mils) has been added to thermoplastics at a rate of 9-10% of the total weight. „ Remainder comprised of 35% filler materials, 25% binder material, and 30% glass beads. „ Glass beads slightly smaller gradation than AASHTO Specification M 247-05 (Type I). „

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Data Collection (Phase II and III) „

Test Sites: „

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A minimum of 5 randomly selected sites as delineated by mile marker location. Within each test site – 5 locations are assessed at intervals of 10’ and includes: edge, center or skip lines. Many sites were established at locations with markings up to two years old. Evaluation criteria includes the following – „ „ „

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Retroreflectivity (ASTM E1710-97 modified) Durability (ASTM D913-00) Photographic Representation 13

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Data Collection (Phase II and III) „

Retroreflectivity readings were collected with LTL 2000 Retrometer „

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30-meter geometry or “driver geometry” (Adopted by ASTM) millicandelas/m2/lux Calibration Provides for reproducibility, accuracy, and repeatability Winter Data Collection 15

Data Collection (Phase II and III) „

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When possible, initial retroreflectivity readings were collected within 14 days of application in order to comply with ASTM Standard D 6359-99. „ Minimum retroreflectance requirements: „ White – 250 mcdl „ Yellow – 175 mcdl 16

Phase IV: Data Reduction „ „

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All raw field data was recorded. Data was transcribed into Excel spreadsheets. Data was processed to find anomalous readings. Plots of Retroreflectivity reading vs. time: Readings displayed significant variability. „ All markings displayed similar patterns. „

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Phase IV: Data Reduction Cavendish/Weathersfield (VT 131 WB) Thermoplastic Markings 450 400

Retroreflectivity (mcdl)

350 300 250

White Edge Line Yellow Center Line

200 150 100 50 0 09/01/2002

01/29/2003

06/28/2003

11/25/2003

04/23/2004

09/20/2004

Date

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Phase IV: Data Reduction Brookfield/Montpelier (I-89 NB) White Edge Line Varied Thickness of Thermoplastic 350

Retroreflectivity (mcdl)

300 250 200

125 mil 90 mil

150 100 50 0 05/24/2002

12/10/2002

06/28/2003

01/14/2004

08/01/2004

02/17/2005

09/05/2005

Date

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Phase IV: Data Reduction Burlington/S. Burlington (I-189) White Edge Line 3M LPM Series 1200 1000 900

Retroreflectivity (mcdl)

800 700 600 Grooved Lines

500

Surface Laid Lines 400 300 200 100 0 06/28/03

10/26/03

02/23/04

06/22/04

10/20/04

02/17/05

06/17/05

Date

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Phase IV: Data Reduction Lyndon/Sheffield (I-91 NB) Epoplex LS50 300

Retroreflectivity (mcdl)

250

200 White Line Skip Line Yellow Line

150

100

50

0 Oct-02

Jan-03

May-03 Aug-03 Nov-03 Mar-04

Jun-04

Sep-04 Dec-04

Apr-05

Jul-05

Date

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Phase IV: Data Reduction „

Estimate for Service Life – Statistical Modeling of the degradation of retroreflectivity: „ „ „

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Roadway Characteristics Traffic Characteristics Other Attributes

Evaluation Considerations: „ „

Large Variability Need for pre-defined benchmark

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Phase IV: Data Reduction Recommended Retroreflectivity Values

1998 FHWA Research-Recommended Pavement Marking Values Type

Non-Frwy

Non-Frwy

Freeway

Option 1

= 45 mph

>= 55 mph

Option 2

= 45 mph

>= 60 mph, >10K ADT

Option 3

= 60 mph

White

85

100

150

Yellow

55

65

100

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Phase IV: Data Reduction „

Thermoplastic Markings: Degradation analysis in terms of retroreflectivity, time since installation, and cumulative traffic passages. „ 19 Roadway Sections. „ 1,100 Individual Measurements. „ 69 Longitudinal Lines. „ Grouped by roadway, material, and color. „

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Phase IV: Data Reduction White Edge Line Retroreflectivity

Non-Freeway White Line Thermoplastic Pavement Markings

/lx)

600

Average Retroreflectivity (mcd/m

2

average retroreflectivity = -56.802Ln(# of cumulative vehicle passes in '000) + 556.66 R 2 = 0.6074 500

400

300

200

100

0 0

1000

2000

3000

4000

5000

6000

# of Cum ulative Vehicle Passes ('000)

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Phase IV: Data Reduction Yellow Line Retroreflectivity

Non-Freeway Yellow Line Thermoplastic Pavement Markings

Average Retroreflectivity (m cd/m

2

/lx)

250

200 average retroreflectivity = -22.459Ln(# of cumulative vehicle passes in '000) + 224.78 R 2 = 0.4466 150

100

50

0 0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

# of Cum ulative Vehicle Passes ('000)

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Phase IV: Data Reduction „

Findings Large Data Sets – more accurate degradation models. „ Use of FHWA recommended minimum retroreflectivity values„

Non-Freeway White Line: X=3100, R2=.60 „ Non-Freeway Yellow Line: X=1230, R2=.45 „ Freeway White Line: X=570, R2=.35 „ Freeway Yellow Line: X=540, R2=.05 „ X=# of cumulative vehicle passes in 1000’s of vehicles „

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Phase IV: Data Reduction „

Additional Analysis: Additional readings required for analysis of degradation in polyurea and epoxy markings. „ Examine data sets for anomalous readings. „ To include other independent variables such as average snowfall amounts, pavement types, raw data, curved vs. straight sections. „

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Remaining Phases „

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Phase V: Economic Analysis of life cycle costs. Phase VI: An evaluation of the deterioration mechanisms of the performance factors. Phase VII: Final Report.

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Questions?

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For further information please contact the Materials and Research Section of the Vermont Agency of Transportation: „ Jennifer Vosburgh, Research Engineer „ (802) 828-2553 „ Kat Patterson, Research Technician „ (802) 828-6945

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