# Strings and surfaces

Strings can be lines, arcs or polylines that are keyed in to the job or they can be selected from any linked files that contain linework.

Surfaces can be any surface in a BIM file, or they can be DTM or TTM surface files.

Add map files using the Layer manager

1. In Trimble Access Roads, tap in the Map toolbar to open the Layer manager and select the Map files tab.

2. Tap Add and then select the map files from the Trimble Access project folder on the controller, or from Trimble Connect if the project you are working in is a cloud project. Tap Accept.

   By default, any file you have linked to the job is visible in the map, indicated by the check mark next to the file name .

3. To make items in the file selectable, tap the file name in the Map files tab. A check mark inside a square indicates items in the file are selectable.

4. To close the Layer manager, tap Accept.

The Roads software treats all road distances, including station and offset values, as grid distances. If a ground coordinate system is defined in the job, the grid coordinates are, in effect, also ground coordinates.

Keying in strings

To key in to the job the lines, arcs or polylines you want to stake, use the Key in menu in the Trimble Access General Survey software.

For more information, see Keying in points and lines.

Next steps

Once you have added the strings in the job, you can:

- Display the cut/fill to a surface during stakeout

- Stake the road