# Tunnel survey

Start a survey to survey the as-built tunnel, stake out set out positions for blast holes, bolt holes, and pipe umbrellas during tunnel construction, and to position machinery in the tunnel.

When starting a survey you are prompted to select the survey style you have configured for your equipment.

Do not change the coordinate system or calibration after you have staked out points, or computed offset or intersection points. If you do, the previously staked out or computed points will be inconsistent with the new coordinate system and any points computed or staked out after the change.

After a scan is completed, you can do the following:

- To review a summary for each station, return to the plan view, tap and hold on the screen and then select Results.
- To see details for the current station, return to the cross section view, tap and hold on the screen and then select Details. See also Review tunnel.
- To edit the tolerance values from either the plan or cross section view, tap and hold on the screen and then select Tolerances. The Station, Overbreak, and Underbreak deltas are updated to reflect the new tolerance values.

## Laser pointer

If you are using a total station equipped with a laser pointer:

- The laser indicates the location of the current position or the selected set out position on the tunnel surface.

- The instrument is automatically set to DR tracking mode with the laser pointer on. The cross section for the current position is displayed on screen.

To disable DR mode, set a target height, or make other changes to the instrument setting, tap the arrow at the right of the screen to access the status bar.

To blink the laser and the tracklight or the target illumination light (TIL) when storing a point measured with DR, select Instrument / EDM settings and then set the number of times the laser will blink in the Blink laser field. The Blink laser field is not available when the Laser power field is set to Extended range flashing (SX12 only).

- The Tunnels software defaults to tracking mode when scanning and measuring in a tunnel. If you select standard mode, you achieve better quality but slower measuring times.
- Using an instrument that is not equipped with a laser pointer requires a different workflow when setting out positions. For more information, see To set out predefined positions.

### 3R Laser Pointer

If you are using a total station equipped with a high-power laser pointer, before storing a point, tap 3R Laser to enable the high-power laser pointer and show the mark on the tunnel surface. The high power laser pointer icon at the bottom right of the screen indicates the laser is active. Tap Measure to measure the position and then tap Store to record the current position in the job's database.

- Even though the high-power laser pointer is not coaxial with the telescope, the instrument can automatically turn to measure to the laser pointer location. When you tap 3R Laser, a preliminary measurement is taken to determine the vertical angle to turn the instrument so that the distance is measured to where the high-power laser pointer is pointing. When you tap Measure, the instrument automatically turns to that location and takes the measurement. The instrument then turns so that the high-power laser again points to the measured position. The preliminary measurement is not stored.
- The calculation of the vertical angle to turn to assumes the horizontal distance to the preliminary measurement is similar to the distance to the high-power laser pointer location. To measure to the high-power laser point when it is near the upper or lower edge of an object, consider using face 1 to take measurements at the lower edge of an object, and face 2 to take measurements at the upper edge of an object so that the preliminary measurement does not overshoot the object you are measuring to.

The high power laser is a class 3R laser that emits laser radiation – do not stare into the beam or view directly with optical instruments.