# To stake out a station on the tunnel alignment

1. Tap the alignment in the map, and then select To station in the Method field.

2. If construction offsets are required, enter the required values in the Horizontal offset and/or Vertical offset field. See Tunnel construction offsets.
3. To select the station to stake:
   - In the Station field, enter the station value.
   - Tap next to the Station field, select List and then select one of the design station values from the TXL file.

   - If you can see the station that you want to measure from your position in the tunnel, tap in the Station field and then turn the instrument to the required station and tap Measure to calculate the station value.

     If you are using a Trimble instrument that has VISION technology, you can tap in the map toolbar to view the video feed and then tap the location in the video (for example the prism or tunnel wall), and then tap Measure to calculate the station value.

4. Enter the Station interval used to determine subsequent station values. Tap and make sure that the correct interval method is selected:

   - The 0 based method is the default method and gives station values that are multiples of the station interval. For example, if the start station is 2.50 and the station interval is 1.00, the 0 based method produces stations at 2.50, 3.00, 4.00, 5.00, and so on.
   - The Relative method gives station values relative to the start station. For example, if the start station is 2.50 and the station interval is 1.00, the Relative method produces stations at 2.50, 3.50, 4.50, 5.50, and so on.

5. Tap Next.

   On the map, a dashed green line is drawn at a right angle from your current position to the alignment. The elevation of your current position and the design elevation of the computed position are shown.

   The cross section shows the target station with your current position projected onto it. Construction offsets appear as yellow lines. If construction offsets are specified, the smaller single circle indicates the selected position and the double circle indicates the selected position adjusted for the construction offsets.

6. Point the instrument at the position you want to measure. To turn the instrument to the nearest point on the alignment, tap Turn.

   If required, tap Options to stakeout options. See Tunnel survey settings and tolerances.

7. When the point is within tolerance, tap Accept to store the point.

   When using a Trimble SX12 scanning total station in TRK mode with the laser pointer enabled, 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. For more information, see Tunnel survey settings and tolerances.

8. Continue staking points along the alignment. To select the previous station, tap the Sta‑ softkey. To select the next station, tap and then tap the Sta+ softkey.

   Tap Esc to return to the Stake alignment selection screen.