SH-71 Managed Lanes

Mr. Timothy Martin was retained to develop rigid and flexible pavement designs for SH 71, which is a major thoroughfare for commuters traveling from Downtown Austin to the Austin Bergstrom Airport, and beyond. The pavement designs incorporated selected Alternative Technical Concepts (ATCs) as accepted by TxDOT. The scope of work included construction phase services regarding material usage, placement issues, specifications review/interpretation,  material selection review, evaluation of subgrade soils properties, and responding to requests for information.

Pavement designs were prepared to meet the specified design life and performance requirements. Flexible designs were prepared using TxDOT’s FPS-21 software. The rigid section designs used the AASHTO Guide for Design of Pavement Structures. These designs met the Mechanistic and Triaxial checks for pavement performance. The Effective PI was specified by TxDOT as the procedure for mitigating expansive clay soils prevalent at the project site in central Texas. The conventional flexible design consisted of a Thin Overlay Mixture (TOM) for a high-performance surface, a Performance Graded Type C Surface and Type B Base Mixture, and a high-quality prime coat under seal. The base layer consisted of an untreated flexible base. Overlay options were allowed and are scheduled in year 15. A continuously reinforced concrete pavement was specified for the SH 71 main lanes east of FM 973 and included a bond breaker with 6-inch cement treated base.