Task 3: Use Topology Rule to Fix Dangles
1.) I created a personal geodatabase in Chapter 7 in the catalog tree and was renamed as MergeRoads.mdb. A new feature dataset was created in MergeRoads.mdb and was named Merge and “next” was clicked.

In the next dialog, Projected Coordinate Systems was clicked and idroads.shp was imported to it for the feature dataset. The XY tolerance was changed to 1 meter and “finish” was clicked.

Merge was right-clicked and the feature class (single) was selected from the import tool. In the next dialog, merge_result.shp was made the input feature class name and merge_result was entered for the output feature class name. The shapefile was then imported by clicking OK.

1) In building a new topology, Merge was right-clicked in the catalog tree in arcmap and the topology tool was selected. In the New Topology box the box next to Merge_result was checked and Add Rule button in the fifth panel was clicked.

‘Must Not Have Dangles’ was selected from the Rule dropdown list in the Add Rule dialog and OK was clicked.

The next and the Finish button were clicked to complete the setup of the topology rule.

After the new topology had been created, YES was clicked to validate it.

QUESTION 3
From the Arc GIS desktop help, the description of “must not have dangles” requires that a line feature must touch lines from the same feature class (or subtype) at both endpoints. An endpoint that is not connected to another line is called a dangle. This rule is used when line features must form closed loops, such as when they are defining the boundaries of polygon features. It may also be used in cases where lines typically connect to other lines, as with streets. In this case, exceptions can be used where the rule is occasionally violated, as with cul-de-sac or dead-end street segments.

QUESTION 4
From the Arc GIS desktop help, the description for must not have pseudonodes requires that a line connect to at least two other lines at each endpoint. Lines that connect to one other line (or to themselves) are said to have pseudonodes. This rule is used where line features must form closed loops, such as when they define the boundaries of polygons or when line features logically must connect to two other line features at each end, as with segments in a stream network, with exceptions being marked for the originating ends of first-order streams.

2) The validation results were saved in a topology layer called Merge_Topology in the merge feature dataset. “Properties” from the context menu of Merge_Topology was selected. Errors tab was clicked and then summary was generated. The summary report showed 96 errors, which implied that Merge_result had 96 dangling nodes.

3) A new dataframe was created in ArcMap and renamed Task 3 with the Merge feature dataset is added to it.

idroads.shp and mtroads_idtm.shp were added to Task 3. Different colours were used in order to differentiate Merge_Result, idroads.shp and mtroads_idtm.

Merge_result was made the only selectable layer.

4) Editor and topology toolbar were made active. Start Editing was selected from the Editor menu. MergeRoads.mdb was selected as the database to edit data form.

The Fix Topology Error tool was selected on the Topology toolbar and the red square was clicked. The red square turned black after it was selected. The Error Inspector was selected on the Topology toolbar. A report appeared and showed the error type (Must Not Have Dangles).

The Fix Topology Error tool was used and the black square was right-clicked. Snap as selected and a Snap Tolerance box appeared. 6 meters was entered on the box.

The two squares then snapped together in one square.