STRUCTURED PAVEMENT MARKINGS 90 TH ANNUAL TRANSPORTATION SHORT COURSE TRAFFIC OPERATIONS SESSION I PRESENTED BY HERBERT BICKLEY, P.E.

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1 STRUCTURED PAVEMENT MARKINGS 90 TH ANNUAL TRANSPORTATION SHORT COURSE TRAFFIC OPERATIONS SESSION I PRESENTED BY HERBERT BICKLEY, P.E.

2 PRODUCTS AND PROCESSES Structured markings have been in use for some time. Structured markings add features that enhance both visual and audible performance of pavement markings. There are several trademark products in use that are considered structured markings. (Rainline, Gulfline, HPS-7, Vibraline, etc.) Most are proprietary in some form whether it be equipment, material, or product packaging.

3 BENEFITS AND DRAWBACKS Wet night reflectivity during inclement weather. Audible feedback. Intensity will depend on the type of markings placed and/or if profile is combined with the application. As with raised pavement markers, not snowplow friendly, but more durable materials can increase longevity. No currently approved standard established.

4 WHAT S AVAILABLE In addition to the products previously mentioned, equipment has been developed and used in the states to expand the application of structured markings. In the past, several of the demonstrations have not been successful which has delayed increased usage and exposure of structured markings. At present, multiple equipment manufacturers, material vendors, and bead vendors have products available that meet current AASHTO and TxDOT specifications.

5 COMPARISON OF LINE TYPES LINE TYPES Flat lines Profiled Large beads Small beads Stochastic Systematic Agglomerate Dots Dot n Line Combs Long Flex Chess

6 EXAMPLE OF DOT LINE ON ROUGH SURFACE RELATIVE DOT SIZE DOTS/FT CAN BE SET BY THE OPERATOR. EXPERIENCE HAS DEMONSTRATED A LOWER DOT/FT YIELDS LARGER DOTS AND HIGHER RETRO VALUES 6 INCH DOT LINE OVER PROFILE BARS STRUCTURED MARKINGS PLACED OVER PROFILE TO PROVIDE WET WEATHER AND AUDIBLE PERFORMANCE 8 INCH DOT LINE DOT LINE PLACED ON LARGE AGGREGATE IS IRREGULAR WITH NO NOTICEABLE EFFECT ON PERFORMANCE

7 EXAMPLE OF DOT LINE ON SMOOTH SURFACE 6 INCH DOT LINE DOT LINE INSTALLED ON HMAC 6 INCH DOT LINE DOT LINE INSTALLED OVER PROFILE TOP VIEW OF DOT TAILS OF DOTS VARY WITH MATERIAL BUT USUALLY WEAR OFF

8 ILLUSTRATION OF LIGHT RAYS ON DOTS

9 EXAMPLE OF EDGES SIDE VIEW STRUCTURED MARKINGS PROVIDE VERTICAL SURFACES FOR OPTICS TO EMBED AND PROVIDE RETROREFLECTIVITY FROM VIRTUALLY ALL ANGLES BEAD COVERAGE TESTING WITH VARIOUS BEAD PACKAGES HAS DEMONSTRATED LARGER BEADS HAVE RETENTION ISSUES AS WITH TRADITIONAL LINES SIDE VIEW FINER GRADATION BEAD PACKAGES WITH HIGH INDEX BEADS HAVE PROVIDED HIGH RETROREFLECTIVITY VALUES BOTH INITIAL AND RETAINED AFTER 6 MONTHS

10 RETROREFLECTIVITY Testing has been conducted with multiple bead packages Some results were unexpected with respect to past knowledge and experience Dynamics of the light source and geometry of the structured markings introduce aspects that conventional retroreflectivity measurement may or may not accurately measure to provide the actual effectiveness of the marking.

11 WET REFLECTIVITY ON ROADWAYS

12 STRUCTURED MARKING INSTALLATION EXAMPLES

13 WHAT NEXT? At this time, 6 TxDOT districts have allowed the installation of structured markings. Other have expressed interest. Structured markings meet the intent of the TMUTCD with respect to solid and broken lines. Materials being used are current TxDOT approved thermoplastic profile and glass beads from several suppliers. Cost of installation is comparable to standard flatline markings. If higher performance requirements are included, the bead package will influence cost.

14 WHAT TO CONSIDER? Safety - The ability to place a pavement marking with an additional safety aspect without an increase in cost. Retrace can be accomplished with 60 mil flat line while retaining the functionality of the original structured marking. Accepting structured markings as equivalent to traditional markings. While this would not guarantee structured markings on all contracts, it would allow additional opportunities for evaluation and monitoring. Developing a structured marking specification once performance and costs are verified.

15 THANKS FOR YOUR ATTENTION Contact Information: Herbert Bickley, P.E. Business Development Cell