# Construction offsets

A point to be staked can be offset by a horizontal or a vertical offset.

During stakeout a construction offset is indicated by a green line, with the double circle indicating the selected position adjusted for the specified construction offset(s).

When you define a construction offset for an alignment, the offset is:

- used for all alignments in the same job.
- used for all subsequent surveys of the alignment in the same job, until a different construction offset is defined.
- not used for the same alignment when it accessed from a different job.

Horizontal construction offsets

When staking stations on the alignment or at a skew offset from the alignment, you can define a horizontal construction where:

- A negative value offsets points to the left of the alignment.
- A positive value offsets points to the right of the alignment.

When staking a station at a skew offset from the alignment, the horizontal construction offset is applied along the skew, not at right angles to the alignment.

When staking stations offset from the alignment or when staking a side slope, you can define a horizontal construction where:

- A negative value offsets points toward the alignment (in).
- A positive value offsets points away from the alignment (out).

When staking a catch point, tap next to the Horizontal offset field to specify if the offset is to be applied:

- Horizontally
- At the slope of the previous element in the cross section

Construction offsets are not automatically applied to a side slope offset. When you stake a side slope, select the Store both catch and construction offset check box to measure and store the catch position. See Catch point..

The following diagram shows a Horizontal offset (1) and Slope previous offset (2) applied to the catch point (3). For the Slope previous option, the slope of the offset is defined by the slope of the side slope (4). The Vertical offset value in the diagram is 0.000.

For points with zero offset, you cannot apply construction horizontal offsets at the slope value of the previous template element.

Vertical construction offsets

You can define a vertical construction offset where:

- A negative value offsets points vertically down.
- A positive value offsets points vertically up.

When staking a side slope from the alignment, tap next to the Vertical offset field to specify if the offset is to be applied:

- Vertically
- Perpendicular to the element in the cross section before the point being staked

The following diagram shows a Vertical offset applied vertically (1) and a Vertical offset applied perpendicular (2) to the side slope (3).