California Department of Transportation

Smoother Pavements

ASTM defined roughness as: The deviations of a surface from a true planar surface with characteristic dimensions that affect a vehicle ride quality.

Smoothing Machine

Smoothness Matters

In a 2002 Federal Highway Administration (FHWA) survey, road condition was cited as the public’s number one criteria for satisfaction.  Other national surveys of road users list smooth pavement as a top highway characteristic. Rough or uneven pavement adversely affects driver safety, fuel efficiency, ride quality, vehicle wear-and-tear, and pavement durability.

Smoothness Specifications

Inertial Profiler Certification Program

File Sharing System

Designing for Smoothness

  • Current Specifications for Smoothness
  • Pilot Incentive/Disincentive Specifications
    • Criteria to Use Specification
    • How to Obtain Approval
    • Letter from Chief Deputy
    • Projects Already Approved to Pilot

Measuring Smoothness

  • International Roughness Index
  • National Rankings
  • How Texture Relates
  • Measuring Devices

Smoothness Publications and Presentations


Related Websites







Please forward any questions/comments/suggestions to Waheed Maroof ( Last updated 11/15/2017.