Transtec leads pavement design for Houston’s SH 249 Extension

Transtec chosen for pavement design on US$520 million Houston project
Asphalt Paving, Compaction & Testing / February 12, 2020 1 minute Read
By David Arminas
The SH 249 Extension Project in the US state of Texas: 100% coverage testing via proof rolling (photo courtesy Transtec Group)

Pavement engineering firm Transtec Group has been chosen as lead pavement designer for the State Highway (SH) 249 Extension Project in Texas.

The winning team for the US$520 million design-build project is headed by Williams Brothers Construction. Work will lengthen the highway in Montgomery and Grimes counties by nearly 39km to provide a link between suburban communities and major roadways.

The new roadway will consist of two segments. Segment 1 will be 22.5km of four-lane controlled-access tollway with intermittent frontage roads; segment 2 will be 16km of two-lane non-tolled rural highway.

The Texas Department of Transportation developed technical specifications to conduct a thorough testing and verification of the constructed roadway. For the 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 76m section of roadbed. This estimates subgrade modulus to ensure it meets the design modulus.

In addition, uniformity of support is being ensured by performing falling weight deflectometer (FWD) testing at 30.5m intervals in each travel lane just before construction of continuously reinforced concrete pavement.

Transtec is also conducting adequacy and uniformity of support measurements for all pavement designs using FWD testing. FWD ensures that field deflections are within allowable limits and that the pavement has been built as intended. According to Transtec, this makes project one of the 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 pavement design services to other projects in the Houston area, including the SH 99 Grand Parkway Project. The SH99 won the American Concrete Pavement Association’s National Award for Excellence in Concrete Pavement for its design and construction. The parkway is a complete loop of 12 segments traversing Chambers, Harris, Liberty and Montgomery counties in the Greater Houston region.

Segment H is being constructed along with segments I-1 and I-2 - an $894 million project covering 85km. At nearly 300km, SH 99 Grand Parkway will be the longest highway loop in the US when it opens in spring 2022.

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