210SUBGRADE

210.1DESCRIPTION—This work is preparation of the roadbed to establish the top of subgrade elevation

for both fills and excavations.

210.3CONSTRUCTION—

Section 206.3(b).

specified in Section 206.3(b) for the type of material placed. For newly placed fills, maintain materials as specified in Section 206.3(b). Where undercutting is not directed, compact and proof roll existing subgrades or subgrades in cut areas as specified in Section 206.3(a)1. Seal all subgrade surfaces that have been constructed or disturbed at the end of each workday with a smooth -drum steel wheel roller in the static mode to promote continuous positive drainage and to minimize infiltration of surface water. Maintain and protect completed subgrade. When the completed subgrade has been in place for more than 60 days or at least one winter season, compact and proof roll the entire subgrade surface as specified in Section 206.3(a)1 before placing the Class 4, Type A geotextile separator and subbase. Promptly reshape and recompact, or remove and replace, damaged or unsatisfactory areas before placement of the geotextile. After acceptance of the subgrade, place a Class 4, Type A geotextile over the completed subgrade for the entire lane width 8 feet or greater before placing the subbase. Place the geotextile as specified in Section 212.3(d)1. Install the geotextile continuously in a longitudinal direction, with the transverse limits extending to within a minimum of 6 inches and a maximum of 12 inches from the interior edge of the pavement base drain. Do not disturb or damage the geotextile during the installation of the pavement base drain. Repair damaged geotextile at no additional cost to the Department.

along each side of the subgrade, to control the elevation. Maintain reference grade lines until after completing the surface and correcting deficiencies. Check subgrade for grade and slope. Test the finished surface for irregularities by using a string line stretched tautly, transversely across the subgrade area, between the reference grade lines. Measure the vertical distance from the string line to the finished grade, at various points along the string line, from one side of the surface to the other. Test for surface irregularities at longitudinal intervals of not more than 25 feet. As an alternative or whenever the Representative suspects an area is deficient or irregular, check the finished surface with a template and 10-foot straightedge. Test the finished surface for irregularities by using a template cut to the required cross -section of the surface. Equip the template with metal or other vertical extensions attached to the top of each end to support a leveling device for checking the cross slope. The bottom of the template is to be at the elevation of the top of the subgrade. Use a 10-foot straightedge to test for longitudinal irregularities in the surface. Hold the straightedge parallel to the road centerline in contact with the surface. Move the straightedge from one side of the surface to the other. Advance along the surface in 5-foot increments. Where subgrade is constructed using an automatic grading machine that cuts the subgrade and is controlled by a reference line or lines, the longitudinal interval for checking the surface cross -section may be increased to not more than 50 feet. Where subgrade is constructed using grading equipment controlled by Survey Grade Global Positioning System (GPS), laser technology, and/or combination thereof, the longitudinal interval for checking the surface cross-section may be increased to not more than 500 feet provided the requirements specified in Section 210.3(d) are met. Correct surface irregularities exceeding 1/2 inch by loosening the surface and removing or adding material as required. Compact the corrected area and surrounding surface by rolling. Recheck the corrected subgrade area for grade and slope.

submit a machine control grading QC Plan to the Department as specified in Section 106.03(b). A t a minimum, the QC Plan must demonstrate that the grading control equipment meets the performance requirements within acceptable tolerances. At a minimum, set construction stakes at right angles to the centerline on tangents and radial offsets on curves at 500-foot intervals the entire length of mainline. In addition, set a minimum of two constructions stakes on each ramp, on each intersecting roadway, and on projects less than 1000 feet in length. Tabulate offsets and elevations of all stakes using Form D-413 (Grade Sheet) located in Publication 122M, Appendix C, and provide to the Representative. Rough grade and fine grade stakes will be accompanied by a guard stake for easy identification. Provide control points and conventional grade stakes at critical locations such as, PC’s, PT’s, superelevation points, and other critical points required for the construction of drainage and roadway structures. Provide other points of reference necessary to establish quality control or for verification of accuracy by the Department. Provide the same Survey Grade GPS network to the Department as that used during construction. The Department will review the network and monitor the project. Check and recalibrate, if necessary, the GPS or laser machine control system at the start of each workday. Test the finished surface at all hinge points and/or centerline, edge of lane, and edge of shoulders on the cross-section at all critical locations and as established in the QC Plan. Correct surface irregularities exceeding 1/2 inch by loosening the surface and removing or adding material as required. Compact the corrected area and surrounding surface by rolling. Recheck the corrected subgrade area for grade and shape. Upon successful quality control testing, notify the Representative the subgrade is ready for acceptance. At a minimum, the Representative will test the finished surface at all hinge points and/or centerline, edge of lane, and edge of shoulders on the cross -section at a random locations every 500 feet for acceptance. Correct all areas exceeding 1/2 inch. If more than 10% of all acceptance tests are determined to exceed 1/2 inch in any phase of the project, the Representative may require stakes and stringline be established as specified in Section 210.3(c). Provide all electronic data files used for the construction of the fine grade of the roadway to the Representative.

210.4MEASUREMENT AND PAYMENT—

shaping and finishing unpaved classes of work, subgrade is incidental to those items of work.