Annotated Literature Review for NCHRP Report 640 (2009)

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136 in terms of wet night and simulated wet night retroreflectivity. Their comparisons are summarized in Table 76. Table 76: Inferences from Statistical Analysis of Retro Reflectivity Results from Different Sections, for Different Conditions Condition Lane Dry Wet night Simulated wet night 1000 ft, Fast Wear in fully recessed same as the wear in non- recessed markings. Retro reflectivity of all marks were substantially reduced Retro reflectivity of all marks were substantially reduced 1000 ft, Middle Wear in recessed was less than wear in non-recessed markings. Retro reflectivity of all marks were substantially reduced Retro reflectivity of all marks were substantially reduced 500 ft ramp Wear in fully recessed same as the wear in non- recessed markings. Retroreflectivity of all marks were substantially reduced Retroreflectivity of all marks were substantially reduced 500 ft curve ---- --- Retroreflectivity of all marks were substantially reduced Note: Wear is indicated by a reduction in retro reflectivity Based on the increase in durability of recessed markings, the authors have presented information on additional cost incurred for equipment and labor needed for creating the recesses and an evaluation of life cycle cost. They report that the cost of making one linear foot of recess is about $0.20, and the cost of placing the thermoplastic material is $0.53 per linear foot (hence a total cost of $0.73 per linear foot). On the basis of consideration of a 3 year life span for a non recessed mark and a six year life for a recessed mark, the authors show that the life cycle cost of thermoplastics material with recessed markings is about $15,000, compared to about $19,000 for similar materials in non recessed markings. 1.29.8 Structural Design No information on structural design of porous asphalt mixtures has been provided. 1.29.9 Limitations No information on limitations of porous asphalt mixtures has been provided. 1.30 “Performance Characteristics of Open-Graded Friction Courses.” Massachusetts Highway Department, Pavement Management Section. Boston, MA. February 15, 2001. 1.30.1 General This paper outlines the Massachusetts Highways Department’s (MHD) experience with Open Graded Friction Course (OGFC) up to 2001. This paper was written to address internal concerns within MHD in regards to the effectiveness and performance of OGFC in Massachusetts.

137 The paper addresses construction issues, maintenance practices, and rehabilitation techniques that are used in Massachusetts. Data from a comprehensive skid resistance study was presented that confirmed that OGFC pavements provide excellent friction. Accident history data was presented for 1998 for both conventional and OGFC sections, to illustrate the added safety benefits of OGFC. The data showed that the wet/dry accident ratio is 13 percent lower on the OGFC sections as compared to typical dense- graded sections. Finally MHD states that OGFC pavements are performing well in Massachusetts with some sections that are 19 years old that are still performing adequately. 1.30.2 Benefits of Permeable Asphalt Mixtures MHD states the following benefits of OGFC as: reduced hydroplaning, increased wet weather friction, reduced splash and spray, reduced wet weather glare, reduced noise, and improved night visibility of pavement markings during wet conditions. 1.30.3 Materials and Design MHD suggests using fibers or polymer-modified binders to allow the OGFC mix temperature to be increased without additional draindown concerns and would allow for more nighttime paving operations. 1.30.4 Construction Practices MHD recommends the following: 1. OGFC should be placed on structurally sound pavement. 2. OGFC should not be relied upon to correct structural problems. 3. OGFC is difficult to feather or taper, thus transition areas should be cut in the old pavement and the OGFC started full depth. 4. Over rolling or rolling over cooled mix can crush the aggregates. Rolling should be done behind the paver, with one or two passes with a medium steel wheel roller. 5. The maximum temperature of the OGFC should not exceed 250°F when a non- modified binder is used. Temperatures in excess of 15°F above the maximum can lead to draindown and fat spots. 6. OGFC should not be placed on projects with heavy vehicle braking, turning, merging or traffic weaving. These areas are prone to debond and pavement delamination. 7. OGFC should be placed when the ambient temperature is 60°F and rising. 8. OGFC should be placed in 19 to 25mm lifts. 1.30.5 Maintenance Practices MHD states that maintenance of OGFC presents problems due to its open surface texture and high voids. Winter maintenance is also of importance because the OGFC pavement temperatures tend to be lower than dense-graded mix.