# Computing a Predetermined Area

TPC allows you to create a traverse of predetermined area based on any other traverse. It can use either a hinged method or sliding traverse leg. Both methods compute the points that define the new area, create a new traverse for the requested area and, if you choose, will create a traverse for the remaining area. Any additional points computed to get the requested area will be assigned point labels AREA, AREA:1, AREA:2, etc.

## Creating an Area

Start with an existing traverse that will be used to create the predetermined area. This traverse does not need to close, but it must include any points that will be used as hinge points and all the points that will be needed to define the requested area.

To divide an existing traverse into two areas, you do not need to create a new traverse. TPC will automatically create a new traverse to define the requested area, and will give you the option to create a traverse that defines the remaining area as well. These traverses will be added to the Traverses Manager.

## Specify Which Area to Use

When you divide an existing closed traverse, two areas are computed: One for the requested area, and one for the remaining area. This creates a dilemma. Which of the two areas should be used in the computations? TPC solves the dilemma by asking you to choose Left or Right. If you choose Left, TPC tries to compute the requested area left of the line from the hinge point or left of the bearing for the slide method.

## Hinge method

• Choose COGO | Predetermined Areas.
• In the Predetermined Area dialog, enter the Hinge Point.
• Enter the area you want.
• Choose the side you want to create the area on. TPC tries to compute the requested area to the left or right of the line from the hinge point across the traverse.
• Choose the Save options you want and name the traverse to be created.

Note: You can specify names for the new traverses or you can let TPC assign them. If you let TPC assign them, they will be Area – Existing Traverse Name and Remainder – Existing Traverse Name.

• Choose OK.

If TPC can't find the requested area, it will display a message stating that it could not find the requested area. You can then enter a new range of points.

## Slide method

• Choose COGO | Predetermined Areas.
• In the Predetermined Area dialog, enter the Bearing/Azimuth you want between the two computed points.
• Choose the side you want to create the area on. TPC tries to compute the requested area to the left or right of the line from the hinge point across the traverse.
• Choose the Save options you want and name the traverse to be created.

Note: You can specify names for the new traverses or you can let TPC assign them. If you let TPC assign them, they will be Area – Existing Traverse Name and Remainder – Existing Traverse Name.

• Choose OK.

TPC will create two points, moving them along their respective ranges. If the requested area cannot be computed, an error message will be displayed.

## Grid vs Ground / Geodetic

Areas are computed based on the distance type of the dialog. If the dialog is set to ground distance at project elevation, the area will be ground distance at project elevation.

## Open Traverses

Beginning in TPC Desktop 2014 R2, you can compute predetermined areas from traverses with the closure types Open and Closed Point to Point. In both cases, TPC forces the closure of the traverse by connecting the first and last control points, creating a Closed Loop traverse.

Note: if the leg that TPC creates with it forces the closure is an existing curve or spiral, you may not get exactly the area you requested. This is because in forcing the traverse to close,m TPC does not consider the curve/spiral, but the traverses created created to store the area or remainder area will include that existing curve/spiral in their point sequence.