Units¶

Each TunnelCAD project stores its own unit settings, controlling how angles, coordinates, and stations are displayed throughout the application. Configure units via File > Settings… > Units.

Angular units¶

TunnelCAD supports four angular unit systems:

Unit	Display example	Description
Degrees	`45.0000` followed by degree symbol	Decimal degrees
DMS	`45`deg`00'00.0000"`	Degrees, minutes, seconds
Gradians	`50.0000g`	Gradians (gon), where 400 gon = 360 degrees
Radians	`0.7854 rad`	Radians

The default angular unit is Gradians.

Note

All angles are stored internally in radians regardless of the display unit. The angular unit setting only affects how values are presented in the interface.

Station format¶

Chainages (stations) can be displayed in two formats:

Format	Example	Grouping
`0+000`	`1+250.000`	Groups of 1000
`00+00`	`12+50.000`	Groups of 100

The default station format is 0+000.

Decimal places¶

Separate decimal-place settings control the precision of displayed values in different contexts. All values range from 0 to 6 decimal places:

Setting	Default	Applies to
Coordinates	3	Northing and Easting values
Elevations	3	Height / elevation values
Angles	4	Angle and bearing displays
Stations	3	Chainage / station values
Offsets	3	Lateral offset values

Coordinate system¶

TunnelCAD uses a standard surveying coordinate system:

Northing (Y) – north-south position, increasing northward.
Easting (X) – east-west position, increasing eastward.
Elevation (Z) – vertical position, increasing upward.

Offset convention¶

Cross-section offsets are measured laterally from the alignment axis:

Positive (+) values are to the right of the alignment direction.
Negative (-) values are to the left of the alignment direction.

This convention applies to both setout offsets and measured offsets in cross-section data.

Bearings¶

Bearings are displayed as surveying bearings measured clockwise from north. Internally, angles are stored as mathematical angles (measured counter-clockwise from east). The conversion is performed automatically:

Bearing = 90 degrees - mathematical angle

Bearings are formatted using the project’s angular unit and angle decimal-place settings.

Gradient¶

Gradient values are stored and displayed directly in percent (%). A gradient of 2.5 means a 2.5% slope. The values are not multiplied by 100 for display – they are already in the correct unit.