Splitting line features
Release 9.2 Last modified August 17, 2007	Print all topics in : "Editing existing features"

About splitting line features

You can easily split line features in ArcMap. Splitting lines results in an existing line feature being broken into several line features. There are several methods to split lines:

• At the location where you click (Editor toolbar > Split tool)
  
• At a specific distance or percentage (Editor menu > Split command)
  
• At intersections, either existing or where lines are extended to meet (Advanced Editing toolbar > Line Intersection tool)
  
• At specific distances, with any left over line length being apportioned among the segments (COGO toolbar > Proportion command)
  

In addition, you can create new point or line features at intervals along a line with the Editor menu > Divide command.

Splitting lines manually

The Split tool is used to manually split one line into two at the location you click with the mouse. For example, you can use the Split tool to divide a street centerline into two features when a new intersecting road is constructed.

The split operation updates the shape of the existing feature and creates a new feature using the default attribute values for the feature class.

Splitting lines at a specified distance or percentage

The Split command on the Editor menu will split a selected line feature into two features. The line can be split from either the start point or end point of the line by using a specified distance value, a percentage of total length, or a m-value. The split operation updates the shape of the existing feature and creates a new feature using the default attribute values for the feature class.

The Split dialog box displays the length of the original feature in current map units to help you split it accurately.



Below are some examples of using the Split command.

• Here is the selected line you will be splitting. It is 100 meters in length.
  
Arrows are shown on the feature to indicate the line's direction, so you can choose whether you want to split the line from the start or end point of the line. These arrows will help ensure that the line is split from the proper orientation.



• This line is split 20 meters from the start point.
  


• This line is split at a percentage of the line's length. In this case, 45 percent.
  



• If your data has m-values, you can also choose to split based on measure units.
  

Splitting lines at intersections

The Line Intersection tool allows you to split line features at their intersections. The lines will be split at the location where you click the mouse. The split operation updates the shape of the existing feature and creates a new feature using the default attribute values for the feature class.

There can be many potential intersections between the lines features, and the intersection points can be either at specific locations in the middle of both lines or at implied intersections along extensions to one or both lines. When a feature needs to be extended to a point of intersection, you can either extend the existing feature or add a new feature.

In the simplest case, there is a single intersection between the line features. In the graphics below, the line features are drawn in black and the pointer is placed at the intersection. The graphic on the right shows red lines leading to an implied intersection. In that case, the lines will be extended to the intersection, then split.



In more complex cases, there can be many points of intersection, although you can split only one intersection at a time. As you move your pointer, the intersection solution closest to the pointer is shown. Click at that location to perform the split.




When working with multipart lines, only one part will be split at a time. Even if more than one part intersects the same line feature, only the part that corresponds to the intersection solution you clicked will be split. Once you've split the first part, simply use the Line Intersection tool again and split the other part at the second intersection.

If you want to split all lines and parts at their actual intersections at once, you can use the Planarize command on the Topology toolbar. To extend all line features and parts, you can use the Extend tool or the Extend/Trim Features task, then planarize the lines.

Splitting lines proportionally (ArcInfo and ArcEditor only)

The Proportion command on the COGO toolbar will split a selected line feature into a number of segments, based on specified distance values. If there is a difference between the feature length and the entered values, this difference is proportioned between all the new segments. Proportion is useful when you are working with exact measurements, such as COGO or survey data.

When you create line features using the construction tools in ArcMap, you can get features that need to be split into specific lengths. The example below shows a line feature that needs to be split into four parts: 13.79 feet, 48 feet, 60 feet and 60 feet. The Proportion command is used to split this feature into the four new features.



The lengths you entered add to 181.79 feet. If the length of the input feature is either longer or shorter than this value, the difference is proportioned among the new features. So if the length of the original feature were 182 feet, it is to be proportioned into features that are: 13.807ft, 48.055ft, 60.069ft and 60.069ft long.

Creating new points or lines at an interval along a line

The Divide command creates points or line segments, depending on whether a point or a line layer is the target, at an interval along a selected line. For instance, you could use Divide to place utility poles along an electric line. You can create a specific number of points that are evenly spaced, or you can create points at a distance interval you choose.



Below are some examples of using Divide to create new point features.

• Here is the selected line you will be dividing. It is 100 meters in length.
  



• A specific number of points, in this case two, are placed along the line and spaced evenly. The endpoints are automatically added, so you will get four new points.
  




• Points are placed every 20 meters. Since 20 divides evenly into 100, all the points are evenly spaced along the line.
  



• Points are placed every 15 meters. Since 15 does not divide evenly into 100, the last two points, 7 and 8, are closer to each other than the other points. This is because Divide does not allocate any left over distances among the points; use the Proportion command on the COGO toolbar to do that.
  


• If your data has m-values, you can also choose to divide based on measure units.
  

If you had a line layer as the target, you would get similar results as the examples. Instead of new point features, you would get a series of line features created at intervals along the original selected line.

Here are some things to keep in mind when using the Divide command:

• Both the source and target layers must be editable.
  
• The target layer can be point or line (either same as or different from the source).
  
• If you divide into a line layer, a series of divided lines are added to the target layer and the original line remains selected so you can delete it if you want. (By checking the Delete selected feature box on the Divide dialog box, the selected line feature will be removed for you.)
  
• The number of features created depends on the input values and the target geometry. With a point layer as the target, the number of points specified plus two—one for each end—will be created. With a line target, the number of output features will be the number of divisions specified.
  
• Divide does not maintain attributes.
  

How to split line features

Splitting lines manually

1. Click the Edit tool .
   
2. Click the line you want to split.
   
3. Click the Split tool on the Editor toolbar.
   
4. Click where you want to split the line.
   

The line is split into two features, where the split operation updates the shape of the existing feature and creates a new feature using the default attribute values for the feature class.

Tips

To split a line at a specific vertex using the Split tool, use the snapping environment to snap the mouse pointer precisely to it. To split a line at the location where a point feature falls on it, you can apply vertex snapping to the snapping environment and snap the mouse pointer precisely to the point. When working with geodatabase features, you can set up split policies that control the behavior of an object's attributes when it is split. If you are working with representations and shape overrides, click here to learn more about how they behave in a split.

Splitting lines at a specified distance or percentage

1. Click the Edit tool .
   
2. Click the line you want to split.
   
3. Click the Editor menu and click Split.
   
4. Choose the split method you want to use.
   
Click the first Split option to split the feature at a certain distance.
Click the second Split option to split the feature at a certain percentage of the whole.
Click the third Split option to use measures (m-values) to split the line.

5. Type a distance, percentage, or m-value.
   
6. Arrows are shown on the selected line to indicate its direction. Click From Start Point of Line if you want to split the feature starting from the first vertex.
   
Click From End Point of Line if you want to split the feature starting from the last vertex.

7. Click OK.
   
The line is split into two features, where the split operation updates the shape of the existing feature and creates a new feature using the default attribute values for the feature class.

Tip

When working with geodatabase features, you can set up split policies that control the behavior of an object's attributes when it is split.

Splitting lines at intersections

1. Click the Line Intersection tool on the Advanced Editing toolbar.
   
2. Click the first feature you want to intersect.
   
3. Click the second feature you want to intersect.
   
4. Optionally, press the O key to set the Intersection Options. You can choose whether a feature is extended to the point of intersection, or a new feature is added.
   
5. Move the mouse pointer to the intersection solution you want. Alternatively, press Tab to cycle through all the intersection solutions.
   
The final click chooses which intersection solution is correct and splits or extends the features at the intersection.

Tip

When lines are split, the operation updates the shape of the existing feature and creates a new feature using the default attribute values for the feature class.

Splitting lines proportionally (ArcInfo and ArcEditor only)

1. Click the Edit tool .
   
2. Click the line you want to proportion.
   
3. Click the Proportion command on the COGO toolbar.
   
4. The direction of the selected line is indicated by arrows on the map. Choose which end to start proportioning by clicking either from the start point or the end point of the line.
   
5. Click the label <Click To Enter Length>, type the distance value, and press Enter to add the length. The Proportioned column shows the GIS length of the feature that will be created. The Proportioned value = (Length / Entered Length) * Feature Length.
   
6. Continue to add lengths until you are done. Press Esc once to get out of enter mode.
   
7. To modify an existing length, either double-click to edit it or press the Spacebar while it is highlighted.
   
8. To move a length up or down the list, highlight it and hold down Ctrl and press the up or down arrow keys, or click the Move Up or Move Down buttons.
   
9. To remove a length from the list, highlight it and press the Delete key, or click the Delete button.
   
10. To duplicate and re-enter a highlighted length, press Alt + D or click the Duplicate button to open the Proportion - Duplicate dialog box.
    
11. Click OK when you're done entering lengths.
    
The line is split proportionally to the length of the measured segments. Any difference between the line length and the sum of the length of the segments is allocated proportionately to the new lines' length.

Tip

If your line feature has COGO fields and valid COGO attributes, the length you entered will be updated for each output feature.

Creating new points or lines at an interval along a line

1. Click the Edit tool .
   
2. Select the line you want to divide.
   
3. Click the Target layer drop-down arrow and click a point layer, or choose a line layer as the target if you want to create a series of new lines.
   
4. Click the Editor menu and click Divide.
   
5. Click the first option and type a number to place a specific number of points evenly along the line.
   

Click the second option and type a number to place the points at a specific interval in map units.

If your data has m-values, you can also choose to divide based on measure units.

6. Optionally, check Delete the selected feature if you want to delete the original line after it is divided.
   
7. Click OK.
   

The line is divided by points placed along the line as specified. If you divided into a line layer, a series of divided lines are added to the target layer and the original line remains selected so you can delete it if you want.

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