Terracon is currently performing construction materials engineering and testing services on Segment 4 of the 121 Tollway located in McKinney, Texas. The project will consist of the construction of a 2.94-mile stretch of the 121 Tollway in Collin County from Hardin Blvd. to the east of Medical Center Drive, including the 121 Tollway and U.S. 75 Interchange within the City of Allen, the City of McKinney, and the Town of Fairview. The four-level interchange will feature six direct-connecting ramps to provide main lane access between the two roadways. The North Texas Tollway Authority also will construct a loop ramp configuration connecting to the service roads. The interchange is expected to open in January 2011. Terracon's scope of work for this project has included multiple tests on the earthwork, concrete, and steel at the site. The earthwork services include proctors, sieve analysis, gradations, lime thickness checks, resistivity, moisture content, bar linear shrinkage, triaxial tests, and densities; the concrete services have included the testing of concrete cores, beams, and cylinders. In addition, Special Inspections of concrete and precast plant observations are also included, as are shop fabrication and field installation of structural steel.