Base Course Elevation Acceptance Criteria for Road Construction

Most DOT base course elevation tolerances are asymmetric — zero tolerance above design grade, with a small allowance below. This asymmetry is not arbitrary. It reflects the structural consequence of each deviation type:

1. Establish control from project benchmarks. Before shooting base elevations, verify your instrument setup against at least two project control points. A misclosure greater than ±0.02 ft means your setup elevation is unreliable — re-setup before recording any data.
2. Define the measurement grid. The grid should match the specification requirement — typically every 50 feet at the left edge of travel lane, at the lane centerline, and at the right edge of travel lane. On multi-lane roads, cover each lane independently.
3. Shoot elevations at each grid point. Record raw elevation at each point. Do not round. Label each point with its station and offset (e.g., Sta 12+50 Lt 6 = left edge of travel lane at station 12+50).
4. Extract design elevations from the plan.Pull the design profile grade elevation at each station from the road design plans or the contractor's design file. For off-centerline points, calculate the design elevation using the design cross-slope.
5. Calculate and flag deviations. Deviation = Measured elevation minus Design elevation. A positive deviation (base above design) requires immediate correction. A deviation between 0 and -0.04 ft passes. A deviation below -0.04 ft (more than 1/2 inch low) requires correction.
6. Document and get sign-off before paving. Compile the deviation table, have the QC manager review and sign, and submit to the resident engineer or DOT inspector for authorization to pave. Paving without this sign-off creates pay item risk on final acceptance.

Note: Always verify tolerance requirements in project-specific special provisions, which may be tighter than the standard specification. The above represents common published standards; state specs are revised periodically.