1 3M Pavement Markings © 3M 2009. All Rights Reserved. 3M Wet Reflective Pavement Marking Technology ASTM Methods for Measuring and Safety for the Visibility.

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Presentation transcript:

1 3M Pavement Markings © 3M All Rights Reserved. 3M Wet Reflective Pavement Marking Technology ASTM Methods for Measuring and Safety for the Visibility Life of the Road

2 3M Pavement Markings © 3M All Rights Reserved. Agenda  The need for Wet Reflective Pavement Markings  NEW 3M Microcrystalline High Index Optics Technology  ASTM Methods of Measuring Wet Retro Reflectivity  Video of Wet Reflective Pavement Markings  Open Discussion and Questions  Wet Reflective Flash Light Demonstrations

3 3M Pavement Markings © 3M All Rights Reserved. You know the challenges of driving at night – in the rain  Rain hitting the windshield  Movement & conditions of the wipers  Steamed windshield  Glare from oncoming cars  Headlight misalignment  Road spray  Light transmission through the rain

4 3M Pavement Markings © 3M All Rights Reserved. “… drivers are three times as likely to be involved in an accident during rainy or wet pavement conditions … Source: Development of Human Factors Guidelines FHWA-RD December, 1999, Page 6 Brodsky & Hakkert (1988) Accident Analysis and Prevention, 20(3) Increased Traffic Safety Risks in Rainy Conditions

5 3M Pavement Markings © 3M All Rights Reserved.

6 3M Pavement Markings © 3M All Rights Reserved. Retroreflectivity Efficient Glass Bead Technology Light enters the bead ….. and is then returned to the driver

7 3M Pavement Markings Defining Refraction?  Refraction – bending of light as it passes from one substance to another. Here, the light ray passes from air to glass and back to air. The bending is caused by the difference in density of the two substances. © 3M All Rights Reserved.

8 3M Pavement Markings © 3M All Rights Reserved. Have you noticed how an object seems to “bend” in water? That’s refraction.

9 3M Pavement Markings © 3M All Rights Reserved. Incoming light in air RI=1.00 Diamonds sparkle because they have a very high refractive index. But unfortunately they’re not too practical for use in pavement markings…. Glass RI=1.5 Higher index beads RI= Cubic zirconia RI=2.1 Diamond RI=2.4 The good news: 3M has developed microcrystalline ceramics with a very high refractive index! Microcrystalline ceramic RI=2.4 Refractive Index is a measure of the degree of bending.

10 3M Pavement Markings © 3M All Rights Reserved. How does refractive index relate to pavement markings?

11 3M Pavement Markings © 3M All Rights Reserved. The bead acts as a lens and focuses light. 1.5 index bead But pigment is needed for retroreflection.

12 3M Pavement Markings © 3M All Rights Reserved. The 2.4 index bead actually bends the light too much! The 1.9 index bead best directs the light in dry conditions 1.5 index bead 2.4 index bead 1.9 index bead

13 3M Pavement Markings © 3M All Rights Reserved. But what happens when we add water?

14 3M Pavement Markings © 3M All Rights Reserved. Water distorts the lens. Light must bend more to hit the target. 1.9 index bead 2.4 index bead The 2.4 index bead best directs the light in wet conditions.

15 3M Pavement Markings © 3M All Rights Reserved. For performance in all weather, one type of bead can’t do it all! ii Dry conditions Optimal Refractive Index (RI) = i Optimal Refractive Index (RI) = Wet conditions

16 3M Pavement Markings © 3M All Rights Reserved.  Dry reflective beads (RI = 1.9) provide maximum reflectivity under dry conditions  Wet reflective beads (RI = 2.4) incorporate water into the optics, providing maximum reflectivity when wet.  They work together to provide higher levels of performance in all weather conditions Introducing the 3M All Weather Dual Optics System

17 3M Pavement Markings © 3M All Rights Reserved. ASTM (American Society for Testing and Materials) Test Methods  ASTM E1710 (dry reflectivity)  ASTM E2177 (wet recovery) -Wetting with water sprayer -Measure after 45 seconds  ASTM E2176 (wet continuous) -High rain fall rate -Specified water sprayer  ASTM E2832 ( new wet continuous) -Low rain fall rate -Specified water sprayer, water pump, wind shield -To be measured after 14 days on the road

18 3M Pavement Markings ASTM E2177 Conditions of Wetness This test measures pavement markings when damp, or simulates testing immediately after a rainstorm Measure dryWet the marking Allow to drain for 45 secMeasure again

19 3M Pavement Markings This test simulates measurement under rain conditions. It best differentiates true wet reflective performance. ASTM E2176 Continuous Wetting Measure dry Continually wet the marking & take reading until they reach steady state.

20 3M Pavement Markings This test simulates measurement under rain conditions. It has a lower rain rate and different droplet size compared to E2176 ASTM E2832 Continuous Wetting Equipment Continually wet the marking & take reading until they reach steady state.

21 3M Pavement Markings © 3M All Rights Reserved. Test Method Comparisons for Sample Pavement Markings Product Dry Reflectivity E2176 Wet Continuous E2832 Wet Continuous E2177 Wet Recovery 380AW 750 mcd350mcd450 mcd500mcd mcd350mcd400mcd500mcd NEW

22 3M Pavement Markings © 3M All Rights Reserved. Test Method Comparisons for All Weather Liquids Element Series Dry Reflectivity E2176 Wet Continuous E2832 Wet Continuous E2177 Wet Recovery Dry Only 1600 mcd75 mcd100 mcd175mcd Series mcd125mcd200 mcd345 mcd Series mcd180mcd325 mcd500 mcd NEW

23 3M Pavement Markings © 3M All Rights Reserved. Wet Reflective Pavement Markings in Action  Pavement Marking Video from Florida  Pavement Marking Video from Pennsylvania Turnpike  Flash light demonstration  Open Discussion and Questions

24 3M Pavement Markings Thank you! © 3M All Rights Reserved.