Updating Friction/Texture Demand Categories for Improved Pavement Design Guidance

The skid qualities of pavements play an important role in road safety. Road surfaces must ensure an adequate level of friction at the tire-pavement interface to provide safe conditions for vehicles. Unfortunately, current asphalt mix design protocols do not explicitly account for friction and texture performance. Furthermore, recent research projects have shown that North Carolina mixes have become finer over the years, resulting in low macrotexture and in some cases compromised skid resistance values in the field. Recently completed projects, RP2020-11 and RP2022-05 have characterized the extent of these issues and proposed performance thresholds to aid North Carolina Department of Transportation (NCDOT) to identify when potential issues exist. To complete the implementation of the outcomes of this work, additional research is now needed to comprehensively integrate the findings from these projects so that an effective pavement friction management plan can be developed and so that the effectiveness of different surfacing and/or mitigation strategies are fully understood. The final integration process should: (1) relate the mixture compositional factors with the initial friction/texture in the field, (2) define methods to control the construction quality of new surfaces in terms of skid resistance demand, and (3) incorporate functional performance considerations in the mix design process by balancing the structural and functional requirements. In light of this need, the proposed research plan will seek to achieve four objectives: (1) validate the proposed friction/texture performance models and their respective investigatory and intervention thresholds; (2) categorize friction demand for existing pavement sections, (3) develop a decision framework that allows identifying the surface characteristics that satisfy friction demand requirements; and (4) develop a quality assurance (QA) protocol to evaluate the pavement surface at the time of construction. These objectives will be met with six tasks: (1) Literature review. (2) Crash rate and threshold validation for alternative surface courses. (3) Develop demand categories for existing pavement sections across the state along with priorities based on crash rates and sites with factors likely to contribute to wet crash rate issues. (4) Develop an evaluation matrix and design guidance for new projects so that the appropriate friction demand category is assigned at the design phase and appropriate material choices can be made at the time of project delivery. (5) Define a quality acceptance protocol to ensure acceptable initial skid resistance after construction. (6) A final report summarizing the methodology, results, and recommendations will be prepared. The primary outcome of the proposed research will include friction demand categories and recommendations for design strategies on sites requiring high friction/texture performance. Additionally, a recommended QA procedure will be proposed to ensure adequate friction/texture after construction. This protocol will support the decision-making to mitigate safety problems. Friction and macrotexture have been shown to closely relate to lane departure wet crashes. Higher crash risks are associated with combinations of friction and macrotexture that result in low skid resistance values. Therefore, by controlling the skid resistance performance on roadways through more informed management or material design practices it could be possible to reduce the number of collisions related to skid resistance problem.

Language

• English

Project

• Status: Active
• Funding: $280540
• Sponsor Organizations:

  North Carolina Department of Transportation

  Research and Development
  1549 Mail Service Center
  Raleigh, NC  United States  27699-1549
• Managing Organizations:

  North Carolina Department of Transportation

  Research and Development
  1549 Mail Service Center
  Raleigh, NC  United States  27699-1549
• Project Managers:

  Bryant, Catherine

• Performing Organizations:

  North Carolina State University

  Department of Civil, Construction and Environmental Engineering
  Raleigh, NC  United States  27695
• Principal Investigators:

  Underwood, Shane

• Start Date: 20240801
• Expected Completion Date: 20260731
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Friction; Pavement design; Quality assurance; Skid resistance; Texture
• Subject Areas: Construction; Design; Highways; Pavements;

Filing Info

• Accession Number: 01937052
• Record Type: Research project
• Source Agency: North Carolina Department of Transportation
• Files: RIP, STATEDOT
• Created Date: Nov 15 2024 4:35PM