Pavement engineering firm The Transtec Group is the lead pavement designer for the Texas State Highway (SH) 249 Extension Project in Montgomery and Grimes counties, Texas. The winning team for this design-build project is headed by Williams Brothers Construction. Transtec’s expertise was selected for this team to produce the best technical and most cost-efficient pavement design proposal.
The $520 million SH 249 Extension Project will expand the highway with approximately 24 miles of new roadway in the Houston area, providing a link between suburban communities and major roadways. The new roadway will consist of two segments: Segment 1 will be 14 miles of four-lane, controlled-access tollway with intermittent frontage roads, and Segment 2 will be 10 miles of two-lane, non-tolled rural highway.
To maintain a high level of quality in this project, the Texas Department of Transportation (TxDOT) developed technical specifications to conduct a thorough testing and verification of the constructed roadway. For this project, 100% coverage testing is being achieved via proof rolling. Subsequently, before construction of pavement layers, the field design subgrade modulus is verified by performing Dynamic Cone Penetrometer Testing at every 250-linear foot section of roadbed to estimate subgrade modulus and to ensure it meets the design modulus. In addition, uniformity of support is being ensured by performing falling weight deflectometer (FWD) testing at 100-foot intervals in each travel lane just before construction of continuously reinforced concrete pavement (CRCP).
The Transtec Group, in addition to developing the pavement design, is conducting adequacy and uniformity of support measurements for all pavement designs, using FWD testing to ensure field deflections are within allowable limits and to ensure that the pavement has been built as intended. This project is one of the very first design-build projects of its kind to require construction verification of the field design subgrade modulus and to evaluate uniformity of support with the use of FWD testing.
Construction for the first segment began in December 2017 and completion is projected for 2021. Segment 2 began in fall 2018 and will be completed in late 2022.
Transtec has provided innovative pavement design services to other projects in the area, including the SH 99 Grand Parkway Project, which won the American Concrete Pavement Association (ACPA) National Award for Excellence in Concrete Pavement in recognition of its outstanding design and construction.