Best Practice for Flexible Pavement Structure Widening Projects

The Texas Department of Transportation (TxDOT) has experienced problems with construction quality and performance on narrow widening projects (e.g., adding a 2- to 5-ft shoulder). Texas has approximately 40,000 lane-miles of Farm-to-Market (FM) roads with 9- to 10-ft-wide lanes. In addition, approximately 20 percent, 26 percent, and 36 percent of roadways with 9-ft, 10-ft, and 11-ft lanes, respectively, have either no shoulder or a 1-ft shoulder. These roads are potential candidates for lane or shoulder widening to improve safety performance and increase capacity. However, due to constraints regarding construction equipment limitations, material selection options and compatibility, construction methods, and other issues, problems with narrow widening projects can arise. These challenges include inadequate compaction at the base layer joint interface, drainage within the pavement and at the pavement surface, either high or depressed surface layer construction joints, and potential safety concerns. To effectively overcome these challenges, TxDOT has initiated this project to prepare a compendium of best practices and lessons learned regarding narrow widening projects. The primary goal of this project is to identify best practices for improving pavement performance on projects involving widening of narrow pavement structures.