Tunnel survey settings and tolerances

• Enter the Start point name, Point code, and Scan interval. Points to be scanned are defined by the scan interval, and include the start and end points that define each element in the template surface.
• Use the On station adjustment option to control where the position will be measured when the tunnel surface does not match the design, for example if the tunnel surface is irregular in places. If selected, Auto OS appears at the top left of the screen. You must specify a station tolerance if using this option. See On station adjustment.
• When measuring manually with a prism, select the Apply target height perpendicular to profile option. This option enables a position to be measured perpendicular to the tunnel profile when using a prism by entering the prism radius as the target height. See Position measurements using a prism.
• If you are using a Trimble VX spatial station, select the VX scanning option for improved scanning performance.

• Select Instrument perspective profile display to display the tunnel profile in the direction the instrument is facing. This option is especially useful when you are facing in the direction of decreasing station, as the tunnel profile is then displayed in the same sense that the instrument is pointing, rather than always assuming you are facing in the direction of increasing station.

• Set the Point name and Point code.
• When measuring manually with a prism, select the Apply target height perpendicular to profile option. This option enables a position to be measured perpendicular to the tunnel profile when using a prism by entering the prism radius as the target height. See Position measurements using a prism.

• Select Instrument perspective profile display to display the tunnel profile in the direction the instrument is facing. This option is especially useful when you are facing in the direction of decreasing station, as the tunnel profile is then displayed in the same sense that the instrument is pointing, rather than always assuming you are facing in the direction of increasing station.

• Set the Point name and Point code.
• Select the Measurement mode for the connected instrument:
  • Select STD to use EDM Standard mode, where the instrument averages the angles while a standard distance measurement is taken.
  • Select FSTD to use EDM Fast Standard mode, where the instrument averages the angles while a fast standard measurement is taken.

  • Select TRK to use EDM Tracking mode, where the instrument constantly measures distances and updates them in the status line.

• To set the total station EDM to TRK mode regardless of the Measurement mode setting when you enter stakeout, select the Use TRK for stakeout check box.

• If you are using the Trimble SX12 scanning total station in TRK mode and the laser pointer is enabled, the Mark point with laser pointer check box is available.

  • When the Mark point with laser pointer check box is selected, the stakeout screen shows the Mark point softkey instead of the Accept softkey. Tap Mark point to put the instrument into STD mode. The laser pointer stops flashing and moves to position itself at the EDM location. When you tap Accept to store the point, the instrument automatically returns to TRK mode and the laser pointer resumes flashing. To remeasure and update the stakeout deltas, tap Measure after you tap Mark point and before you tap Accept.
  • When the Mark point with laser pointer check box is not selected, the Stakeout screen shows the Accept softkey as usual and the point is measured at the location of the laser pointer.

• In the Start point field, enter the required point name for the first set out point. The names of subsequent set out points will automatically increment from the entered point name.

• If you are setting out all blast holes, enter the Start delay and Mark delay values to control the automated set out process.

  The Start delay gives you time to walk to the location of the first point to be marked.

  The Mark delay is the length of time, in seconds, that the laser pointer flashes once the position is found, which gives you time to mark the point on the tunnel wall.

  When a position is found within tolerance, the Mark point event sounds and:

  • If the instrument has a tracklight, the laser pointer and the tracklight flash for the period defined in the Mark delay field.
  • If the instrument is a Trimble SX12 scanning total station, the laser pointer changes to solid and the Target Illumination light (TIL) flashes for the period defined in the Mark delay field.

• Select Instrument perspective profile display to display the tunnel profile in the direction the instrument is facing. This option is especially useful when you are facing in the direction of decreasing station, as the tunnel profile is then displayed in the same sense that the instrument is pointing, rather than always assuming you are facing in the direction of increasing station.

For all survey methods you can display guide lines in the cross section view. Select:

• Display profile vertical centerline to display a vertical green line through the alignment or, if the alignment has been offset, the offset alignment.
• Display spring line to display a horizontal green line through the alignment or, if the alignment has been offset, the offset alignment.
• Display alignment vertical centerline to display a vertical orange line through the alignment.
• Display floor line to display a horizontal orange line through the alignment or, if the alignment has been offset, the offset alignment.

The available fields depend on the survey method.

• For Auto scan, set the Station, Overbreak and Underbreak tolerances, and the number of Iterations.
• For Position in tunnel, set the Overbreak and Underbreak tolerances.
• For Set out, set the Position tolerance and the number of Iterations. See Set out position tolerance.