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Research and Development (R&D) Project Sites

Project Information
Project ID:   FHWA-PROJ-10-0068
Project Name:   Development and Demonstration of Pavement Friction Thresholds, Including Friction Numbers and Macrotexture; Phase II Purchase and Delivery of Continuous Friction Measuring Equipment (CFME); Acceptance Testing and Demonstration of CFME
Project Status:   Active
Start Date:  November 22, 2010
End Date:  August 28, 2017
Contact Information
Last Name:  Sherwood
First Name:  James A
Telephone:  202-493-3150
E-mail:  jim.sherwood@dot.gov
Office:   Office of Infrastructure Research and Development
Team:   Infrastructure Analysis and Construction Team [HRDI-20]
Program:   Innovative Pavement Research and Deployment
Project detail
Roadmap/Focus area(s):   Infrastructure Research and Technology Strategic Plan and Roadmap
Project Description:   In phase I, the contractor performed a literature review on pavement friction and macro-texture and safety. They wrote a report on theoretical vehicle, tire, and pavement interactions as they relate to skid crashes in order to recommend the best equipment to measure friction and macro-texture. In phase III, the contractor will use the recommended equipment (purchased by the Federal Highway Administration) to test about 700 miles in several friction demand categories, in four States, to develop Pavement Friction Thresholds and Management Programs.
(1) Perform a literature review, and establish theoretical relationships for tire-pavement interactions; in order to recommend the best piece of Continuous Friction Measurement Equipment (CFME) for developing friction thresholds for maintenance intervention
(2) Perform friction tests using the best CFME (on several friction demand categories in at least four States) to establish threshold  levels for friction and macro-texture, based on the procedures in the 2010 AASHTO Guide for Pavement Friction and possibly newly developed statistical methods if warranted
(3) Assist these four State DOTs to develop "Pavement Friction Management Programs"
(4) Develop training materials to document the new procedures.
Field Test:   The contractor will be field testing for the friction and macrotexture of a variety of pavement classes, types, and traffic levels.
Test Methodology:   The approach is to relate crash rates and severities, to friction numbers and macrotextures for verifying pavement friction thesholds for maintenance intervention.
Partners:   Federal Highway Administration: Office of Research, Development, and Technology - Office of Infrastructure Research and Development; Role(s): Technical
Expected Benefits:   States have found benefit-cost ratios of up to 15, based on crash reductions. Pavements with high levels of friction have reduced numbers of run off the road crashes.
Project Findings:   The literature review and theoretical relationships reports found that a friction tester operating at about 38 % slip was the optimum in terms of duplicating the current locked wheel devices (at 100 % slip,) i.e. sensitive to the pavement, versus operating at in the range of the peak frictions (at 10 to 20 % slip) and zones where the tires dominate.  Furthermore a CFME known as the Sideways Coefficient Routine Investigatory Machine (SCRIM) developed and currently manufactured in the UK, was identified as the best, because by running the tire  at a 20 degree angle they create 38 % slip without applying any type of mechanical braking system to the test wheel.  The SCRIM also has a track history of testing at least 150 miles per day.
FHWA Topics:   Safety--Roadway Departure Safety
TRT Terms:   Friction
FHWA Disciplines:   Pavement and Materials
Subject Areas:   Highways


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