The aggregates selected for use in seal coats or surface treatments should provide sufficient friction to satisfy the frictional demands of the roadway. The TxDOT Wet Weather Accident Reduction Program (WWARP) provides methods to ensure that pavements with good skid-resistant characteristics are constructed. The guidelines address three separate but interrelated aspects of pavement friction safety: accident analysis, aggregate selection, and skid testing.

For complete details on aggregate selection, refer to the TxDOT WWARP in the Pavement Design Manual. The designer should consider the guidelines presented in the WWARP and, using engineering judgment, determine the overall frictional demand of the roadway surface. TxDOT Standard Specification Item 316, Seal Coats, states “…. unless otherwise shown on the plans, furnish aggregate with a minimum “B” (i.e., A or B is permitted) surface classification.”