subgrade

[ suhb-greyd ]

/ ˈsʌbˌgreɪd /

Civil Engineering, Building Trades.

the prepared earth surface on which a pavement or the ballast of a railroad track is placed or upon which the foundation of a structure is built.

beneath the finished ground level of a project.

Origin of subgrade

First recorded in 1895–1900; sub- + grade

The pavement laid was bitulithic and the subgrade was an old macadam road built by the County.

Third Biennial Report of the Oregon State Highway Commission |S. Benson, W. L. Thompson, R. A. Booth, Herbert Nunn
When the work was finished, a subgrade reversed-grade drain carried the water to the shaft sump by gravity.

Transactions of the American Society of Civil Engineers, Vol. LXVIII, Sept. 1910 |B. H. M. Hewett
The side-walls and subgrade electric conduits were water-proofed with felt and pitch.

Transactions of the American Society of Civil Engineers, Vol. LXVIII, Sept. 1910 |B. H. M. Hewett
In each grade and subgrade date of commission, appointment, or warrant determines the order of precedence.

Manual for Noncommissioned Officers and Privates of Cavalry of the Army |War Department.

Some engineers advocate that in preparing the subgrade, the earth be thoroughly rolled; others prefer not to roll the subgrade.

American Rural Highways |T. R. Agg

subgrade

/ (ˈsʌbˌɡreɪd) /

the ground beneath a roadway or pavement