Plain-language definitions for survey, grading, pipe installation, horizontal alignment, machine guidance, and field documentation terms. 66 terms across 6 categories.
An as-built drawing (also called record drawing or red-line drawing) is a set of construction plans marked up to show the actual constructed positions of all improvements, deviations from design, and field changes.
Field DocumentationAn as-built survey documents the actual constructed positions of installed improvements — pipes, structures, road centerlines, and utilities — as opposed to the design positions shown on construction plans.
Field DocumentationA backsight is a rod reading taken to a point of known elevation — typically the benchmark — immediately after the leveling instrument is set up.
Survey & LevelingA benchmark is a surveyed point of known elevation used as a reference datum for construction grade work.
Survey & LevelingBenchset refers to the initial elevation establishment procedure on a construction project — verifying the benchmark, connecting to a control network, and setting the reference elevation for all subsequent grade work on the job site.
Survey & LevelingBlade control refers to the automated or semi-automated adjustment of a motor grader or dozer blade elevation and cross-slope based on input from a machine guidance system.
Machine GuidanceA blue-top stake (also called a grade stake or hub) is a wooden stake driven so that its top is at the design grade elevation, allowing a grading equipment operator to use the tops of the stakes as a direct grade reference.
Grade & EarthworkA borrow pit is an off-site or on-site excavation area used as a source of fill material when a project does not generate enough suitable cut to balance.
Grade & EarthworkA catch basin is an inlet structure in a storm drainage system with a sump at the bottom designed to capture sediment and debris before stormwater enters the pipe system.
Pipe & DrainageA lift is a single layer of fill material placed and compacted before the next layer goes down.
Grade & EarthworkA control line is a surveyed reference line established on a construction site from which horizontal measurements are made to set the location of structures, pipes, road edges, and other improvements.
Survey & LevelingA control point is a surveyed location with known coordinates (northing, easting, elevation) used as the starting reference for layout and grade work on a project.
Survey & LevelingCross-slope is the transverse slope of a road or surface measured perpendicular to the direction of travel.
Grade & EarthworkThe crown of pipe is the highest interior point of a pipe's cross-section — the top of the inside of the pipe.
Pipe & DrainageA curb inlet is an opening in the vertical face of a road curb that admits stormwater runoff into the storm drain system.
Pipe & DrainageCut and fill is the earthwork process of excavating material from areas above design grade (cut) and placing it in areas below design grade (fill) to shape a site to plan elevations.
Grade & EarthworkA cut stake is a grade stake where the existing ground elevation is higher than the design grade, requiring material to be removed (cut).
Grade & EarthworkA daily field report (DFR) is a written record of construction activities completed on a given day, including crew sizes, equipment deployed, work performed, quantities installed, weather conditions, and any issues or delays.
Field DocumentationA design surface is a three-dimensional terrain model representing the finished grade of a construction project as designed by the engineer.
Machine GuidanceDifferential leveling is the surveying process of determining elevation differences between points by measuring backsight and foresight rod readings from a level instrument.
Survey & LevelingDrain slope is the grade percentage or ratio at which a drainage pipe is installed to ensure adequate gravity flow.
Pipe & DrainageA fill stake is a grade stake where the existing ground elevation is lower than the design grade, requiring material to be added (filled).
Grade & EarthworkFinal grade is the finished elevation of a constructed surface after all grading, paving, or concrete work is complete — the last-placed layer at its design elevation.
Grade & EarthworkA foresight is a rod reading taken to a point of unknown elevation after a backsight has established the Height of Instrument.
Survey & LevelingA grade check is a field verification shot taken to confirm that installed construction (subgrade, pipe, curb, concrete) is at or within tolerance of the design elevation.
Grade & EarthworkGrade percentage is the ratio of vertical rise to horizontal run, expressed as a percent.
Grade & EarthworkA grade rod is a numerical value representing the distance from the top of a grade stake (or instrument sight line) to the design subgrade elevation.
Grade & EarthworkA headwall is a concrete or masonry retaining structure at the inlet or outlet of a culvert or storm drain pipe, designed to prevent erosion, retain the embankment, and control flow.
Pipe & DrainageHeight of Instrument (HI) is the elevation of the horizontal line of sight through a level instrument at a specific setup location.
Survey & LevelingA hub and tack is a precision staking method where a wooden hub (stake) is driven close to design elevation and a surveyor's tack (small nail) is driven into the top of the hub at the exact design location, providing both a precise horizontal position and elevation reference.
Survey & LevelingAn in-cab display is the screen inside a grading machine (dozer, motor grader, excavator) showing the operator real-time information from the machine guidance system — current blade elevation, cut/fill to design, cross-slope, and alignment position.
Machine GuidanceInstrument height (also called Height of Instrument or HI) is the elevation of the line of sight of a leveling instrument at a given setup location.
Survey & LevelingThe invert elevation is the elevation of the lowest inside surface of a pipe, channel, or culvert at a specific point.
Pipe & DrainageMainfall is the primary drainage direction slope of a surface — the steepest slope toward which water flows.
Grade & EarthworkManhole drop is the difference in invert elevation between incoming and outgoing pipes at a manhole.
Pipe & DrainageA mass haul diagram plots cumulative earthwork volume against station along a linear project, showing where material is cut, where it is filled, and how far it must be hauled.
Grade & EarthworkMoisture content is the weight of water in a soil expressed as a percentage of the dry soil weight.
Grade & EarthworkAn offset stake is a construction stake set a measured horizontal distance from the actual construction feature (centerline, edge of pavement, pipe trench) to keep the reference point out of the work zone.
Survey & LevelingOver-excavation (overex) is digging below the required subgrade elevation, either intentionally — to remove unsuitable soil and replace it with engineered fill — or accidentally, through poor grade control.
Grade & EarthworkThe Point of Curvature (PC) is the point where a tangent alignment transitions into a horizontal curve — the beginning of the curve.
Horizontal AlignmentThe Point of Intersection (PI) is the point where two tangent lines of a horizontal curve intersect.
Horizontal AlignmentPipe fall is the total vertical drop across a pipe run, calculated as the pipe length multiplied by the grade percentage divided by 100.
Pipe & DrainagePipe grade is the slope of a gravity pipe, expressed as a percentage or ratio of vertical fall to horizontal run.
Pipe & DrainageThe Proctor test (ASTM D698 standard, ASTM D1557 modified) is a laboratory test that determines the maximum dry density and optimum moisture content of a soil.
Grade & EarthworkThe Point of Tangency (PT) is the point where a horizontal curve ends and the alignment returns to a tangent (straight) section.
Horizontal AlignmentA punch list is a document prepared near the end of a construction project that lists incomplete or defective work items that must be corrected before the project receives final acceptance.
Field DocumentationResection is a surveying technique where an instrument is set up at an unknown location and oriented by taking observations to two or more known control points to calculate the instrument's position.
Survey & LevelingRip-rap is a layer of large, angular stones placed to protect soil surfaces from erosion caused by water flow — typically at culvert outlets, channel banks, and slope faces.
Pipe & DrainageA rod reading is the numerical value observed on a leveling rod (grade rod, Philadelphia rod) through the crosshair of a level instrument.
Survey & LevelingRough grade is the approximate graded elevation established by earthmoving equipment after bulk cut and fill operations are complete, typically at a specified tolerance above the finish subgrade to allow for base course material.
Grade & EarthworkA shot log is a field record of survey observations — elevations, positions, and descriptions of points measured during grade verification, as-built surveys, or layout work.
Field DocumentationShrink factor is the percentage decrease in soil volume from its natural bank state to its final compacted state in a fill.
Grade & EarthworkThe spring line of a pipe is the horizontal plane passing through the center (widest point) of the pipe cross-section.
Pipe & DrainageA station equation is a notation that reconciles a discontinuity in stationing along a highway alignment, typically caused by alignment revisions during design.
Horizontal AlignmentA stringline is a taut line set between grade stakes or pins at a known offset and elevation, used as a visual and physical reference for checking grade, alignment, and curb or pipe placement.
Survey & LevelingSubgrade is the compacted native or imported soil layer that forms the foundation beneath road base, pavement, or structure slabs.
Grade & EarthworkA submittal is a document or sample submitted by a contractor to the engineer or owner for review and approval before a material or product is incorporated into the work.
Field DocumentationSwell factor is the percentage increase in soil volume when material is excavated from its natural (bank) state to a loose state in the truck or stockpile.
Grade & EarthworkTraverse closure is the process of verifying the accuracy of a series of connected survey measurements by returning to the starting point and calculating the misclosure — the difference between the computed and known coordinates of the starting point.
Survey & LevelingA turning point is a temporary point used in differential leveling to allow the instrument to be moved forward while maintaining an elevation reference.
Survey & LevelingGradelog puts your job library, calculators, and AI field assistant on your phone — so you have answers when you need them most.
Get started free →