CAD Drafting

Overview#

Computer-aided drafting is the primary production tool of the modern survey office. CAD transforms processed field data into clear, accurate, and professional survey drawings -- boundary maps, topographic surveys, ALTA/NSPS Land Title Surveys, construction plans, and records of survey. While the software handles the mechanics of drawing, the surveyor must command the standards, conventions, and professional judgment that make a drawing correct, readable, and legally defensible.

A survey drawing is a legal document. Every line, symbol, dimension, and annotation carries professional weight. Poor drafting obscures good fieldwork; disciplined drafting communicates it clearly.

The drawing is what the client, the attorney, the title company, and the court will see. It must be unambiguous, complete, and adhere to accepted standards. Your professional reputation lives on your drawings.

Survey CAD Standards#

Why Standards Matter

Without enforceable standards, every drafter invents their own conventions, making collaboration difficult, quality control unreliable, and deliverables inconsistent. Survey CAD standards ensure that:

• Any drafter in the office can work on any project
• Drawings are internally consistent and professionally formatted
• Quality review is efficient because reviewers know what to expect
• Files exchanged with clients, engineers, and agencies are compatible
• Drawings are defensible if challenged in legal proceedings

Common Standard Frameworks

Several organizations publish CAD standards relevant to surveying:

Most survey firms develop their own CAD standards manual, drawing from published frameworks and tailoring them to their practice.

Layer Naming Conventions#

Structure

A well-designed layer naming system is hierarchical and descriptive. A common structure uses discipline, major category, and modifier:

[Discipline]-[Major]-[Minor]-[Status]

For example: V-BNDRY-LINE-EXIST (Survey, Boundary, Line, Existing)

Standard Survey Layers

Best Practices

• Never use Layer 0 for production geometry. Reserve it for block definitions.
• Do not create layers on-the-fly. Add new layers to the office template first.
• Freeze or turn off layers rather than deleting content. Deleted geometry cannot be recovered.
• Use layer colors that print well. Assign plot styles (CTB/STB) that produce appropriate line weights regardless of screen color.

Linetype Standards#

Linetypes communicate the nature of features on a drawing without requiring the reader to consult the legend for every line:

Linetype Scale

Linetype scale must be set so that dashes and gaps are visible at the plotted scale. A common approach:

• Set the global linetype scale (LTSCALE) based on plot scale factor
• Use LTSCALE = plot_scale_factor (e.g., 40 for 1" = 40')
• Fine-tune individual entities with CELTSCALE if needed

Text and Dimensioning Standards#

Text Heights

Text must be legible at the plotted scale. Standard minimum plotted text heights:

Font Selection

• Use a single, professional font family throughout the drawing
• RomanS or Simplex are standard for engineering/survey work in CAD
• Avoid decorative or variable-width fonts
• TrueType fonts (Arial, Calibri) are acceptable for title blocks and notes but may display inconsistently across platforms

Annotation Best Practices

• Place bearing and distance labels on the outside of boundary lines, reading left-to-right and bottom-to-top
• Maintain consistent text rotation -- bearings read along the line direction
• Avoid overlapping labels; use leaders to offset crowded areas
• Curve data should be placed in a table or in a clear callout near the curve, not stacked along the arc
• Use consistent decimal places: bearings to the nearest second, distances to the nearest hundredth of a foot

Point Plotting and Annotation#

From Processed Data

Point plotting is the foundation of most survey drawings. The typical workflow:

1. Export coordinates from the point database in a standard format (PNEZD or CSV)
2. Import into CAD using the survey software's import routine
3. Apply the code library to assign symbols, layers, and linework connections automatically
4. Review and clean the plotted points -- verify symbol placement, correct mis-codes, and complete linework

Point Symbols

Standard survey point symbols should be defined as CAD blocks at a consistent size:

Point Annotation

Each plotted point should display, at minimum:

• Point number -- For internal reference and traceability to field notes
• Elevation -- For topographic surveys; suppress for boundary-only work
• Description -- Feature description from the code library

Annotation placement should follow consistent rules to avoid clutter: point numbers above-right, elevations below-right, descriptions below-left (or per office convention).

Drawing from Field Data#

Boundary Surveys

1. Plot all control and boundary monuments
2. Connect boundary corners with lines on the boundary layer
3. Annotate each course with bearing and distance
4. Add curve data for any curved boundaries
5. Label all monuments with type, size, and condition
6. Show adjoiners with their record information
7. Add easements, setbacks, and encroachments
8. Include area calculation results

Topographic Surveys

1. Plot all field points with appropriate symbols
2. Generate a surface model (TIN or grid) from elevation data
3. Create contours from the surface at the specified interval
4. Label index contours (typically every 5th contour)
5. Add spot elevations at critical locations (high/low points, drainage structures, building corners)
6. Draw planimetric features (buildings, pavement, fences, walls, vegetation lines)
7. Add utility information from locate data

ALTA/NSPS Land Title Surveys

ALTA/NSPS surveys have specific drawing requirements per the current Minimum Standard Detail Requirements:

• Show all matters disclosed by the title commitment
• Locate all improvements, utilities, and encroachments
• Show measured boundary with bearings and distances
• Include flood zone designation and community panel number
• Reference the specific Table A items included
• Certification language per the Standards

Title Block and Sheet Setup#

Title Block Elements

Every survey drawing must include a title block containing:

Sheet Sizes

Scale Selection

The drawing scale must be chosen so that the survey fits within the sheet borders with adequate room for annotations, notes, and the title block:

Select the largest scale (most detail) that fits the sheet. Readability is paramount. If the survey does not fit at an adequate scale, use multiple sheets with a key map.

Coordinate Display#

Grid Coordinates

When displaying state plane or projected coordinates on a drawing:

• Show coordinates for a minimum of two points (to allow the reader to verify orientation and scale)
• Label the coordinate system, datum, realization, and units (e.g., "California Coordinate System of 1983, Zone 5, NAD 83(2011), epoch 2010.00, US Survey Feet")
• Display coordinates in a table or near the control point symbols
• Indicate whether coordinates are grid or ground

Ground vs. Grid

If ground distances are shown on the drawing (the common practice for boundary surveys), include a note stating the combined scale factor used and whether bearings are grid, record, or astronomic.

Bearing and Distance Annotation#

Bearing Format

Bearings should be annotated in standard surveying format:

• N 45°30'15" E (not 045-30-15 or 045.5042°)
• The degree symbol (°), minute mark ('), and second mark (") must be clearly rendered
• Place the bearing label parallel to the line, reading in the direction of travel

Distance Format

• Distances to the nearest hundredth of a foot (US Customary): 150.25'
• Distances to three decimal places in meters: 45.835 m
• Use a consistent number of decimal places throughout the drawing

Curve Data

Curve data should be presented consistently. A common format for boundary maps:

L = 125.67'     (Arc length)
R = 500.00'     (Radius)
Δ = 14°24'02"   (Central angle)
CB = N 52°15'30" E  (Chord bearing)
C = 125.32'     (Chord length)

For complex maps with many curves, a curve data table is cleaner:

Contour Generation#

From Surface Models

Contour lines are generated from a Triangulated Irregular Network (TIN) or grid surface model:

1. Build the TIN from all topographic points
2. Review the TIN -- Delete or flip edges that create unrealistic surfaces (e.g., triangles spanning a road ditch)
3. Add breaklines along ridges, ditches, curbs, walls, and other linear features that control surface shape
4. Generate contours at the specified interval
5. Smooth contours carefully -- excessive smoothing can move contours away from survey data; too little smoothing produces angular, hard-to-read lines
6. Label index contours and check that contours do not cross, merge, or branch

Contour Intervals

Common CAD Workflows#

Template Setup

1. Start every project from the office CAD template
2. The template should include: standard layers, text styles, dimension styles, linetypes, title block, north arrow, scale bar, and standard notes
3. Set the coordinate system and units before importing any data
4. Configure model space units to match the project coordinate system (feet or meters)

Quality Control Checklist

Before finalizing any survey drawing:

• All boundary lines are properly connected (no gaps or overshoots)
• Bearings and distances match the computation records
• Monument symbols and descriptions are correct and complete
• Curve data is complete and consistent (L, R, delta, CB, C)
• Area calculations are shown and verified
• Adjoiner information is shown
• Easements and encroachments are clearly depicted
• Title block information is complete and correct
• Professional stamp/seal area is properly placed
• North arrow and scale bar are present and correct
• Basis of bearings is stated
• Datum and coordinate system are identified
• Legal description reference is included
• Notes are complete and applicable to the project
• Text is legible at plotted scale
• Linetypes display correctly at plotted scale
• Drawing plots correctly on the intended sheet size

Key Takeaways#

• Standards are non-negotiable. Consistent layers, linetypes, text heights, and annotation conventions make drawings professional, reviewable, and defensible.
• Layer discipline is the foundation of an organized drawing. Every entity should be on the correct layer from the start -- fixing layer assignments after the fact is time-consuming and error-prone.
• Scale and text height must be coordinated so that all annotations are legible at the plotted scale.
• Point plotting drives the drawing. A well-structured code library and import routine can automate much of the drafting; invest the time to maintain both.
• Bearing and distance annotation follows surveying convention -- not engineering or architectural convention. Use standard bearing format and annotate courses consistently.
• Quality control checklists catch the errors that familiarity blinds you to. Use one for every drawing, every time.
• The drawing is a legal document. Treat every line and label as if it will be examined in a courtroom, because it might be.

References#

1. Ghilani, C.D. & Wolf, P.R. Elementary Surveying: An Introduction to Geomatics (13th Ed.). Pearson, 2012. Chapter 18.
2. National Institute of Building Sciences. United States National CAD Standard (Version 6). NIBS, 2015.
3. ALTA/NSPS. Minimum Standard Detail Requirements for ALTA/NSPS Land Title Surveys. American Land Title Association/National Society of Professional Surveyors, 2021.
4. Anderson, J.M. & Mikhail, E.M. Surveying: Theory and Practice (7th Ed.). McGraw-Hill, 1998.
5. Autodesk. "AutoCAD Civil 3D Survey Documentation." Autodesk Inc.
6. Carlson Software. "Carlson Survey User Documentation." Carlson Software Inc.