Edit street and curves

The Edit street/curves tool Edit street/curves tool provides handles to graphically edit street width, sidewalk width, and overall curvature. To edit streets, do either of the following:

  • Click the Edit street/curves tool Edit street/curves tool.
  • Press C.
  • Click Graph > Edit Streets/Curves from the main menu.

Straight versus smooth

Streets can be created either straight (default) or smoothly curved. To quickly switch between the two states, click Graph > Set Curve Straight and click Graph > Set Curve Smooth in the Graph main menu.

Curve Straight and Curve Smooth tools
Curve Straight and Curve Smooth tools are shown.

To automatically choose between those types, you can use Graph > Curves Auto Smooth. Here you have two parameters:

  • Threshold angle determines the minimum angle for curve smoothing.
  • Horizontal optimize set streets in front of slopes to straight to prevent oscillations.

Street editing

Once you activate the Edit street/curves tool Edit street/curves tool, handles are displayed for selected streets or nodes. There are two types of handles: curve handles and street width handles. When a single node is selected, only the curve handle is shown. When a single street is selected, a combined curve and street width handle is displayed. When selecting multiple streets, only the street width handle is shown.

Left: Curve handle. Right: Curve and street width handle
The left image shows the curve handle. The right image shows the curve and street width handle.


To lock the direction, press the Shift key before dragging a curve handle.

Curve handles

Each graph segment has two curve handles, one attached at the start and end nodes of the segment. The green handles drive the start and end direction of the street. The yellow circle allows moving the node. The dashed blue line (which is only visible when the you hover over one of the curve handles) indicates the local weight of the curve.


The spline is mathematically defined by the two end points of the dashed blue lines, plus the segment's start and end points.

To edit either the horizontal or vertical components of a curve handle, change the viewing angle relative to the segment node. A steep angle allows you to edit the horizontal component, with a glancing viewing angle of the vertical component.

Curve handles
Curve handles are shown.

The green circle of the curve handle indicates the smoothing type of the node (manual direction, straight, or smooth). Clicking a green circle while pressing the Ctrl key switches between the types.

Curve handle types
The images show the indication of node type in a green circle: (left) smooth with manual directions (middle) straight (right) smooth with automatic directions.

The segmentation of the street shapes defines the segmentation of the neighboring lot shapes. The overall number of segments per curve can help you avoid issues such as narrowly subdivided facades.

Principle street handles

When an intersection has the type Freeway or Junction and has three or more connecting streets, the curve handles are accompanied by principle street handles. These allow the principle street at an intersection to be edited, changing the intersection geometry.

Street handles
Dark green principle street handles (above, left) indicate that the default principle street will be chosen. Once a principle street is specified manually, the handles are colored light green (right).

Specify the desired principle streets by dragging a principle street handle from one street to another.


Dragging any principle street handle into the yellow circle with clear the principle street at the intersection results in the default behavior.

Street width handles

You can edit the dimensions of a street with the StreetWidth handle. Drag the small green rectangles to individually set the width and offset of the street shape and the widths of the right and left sidewalks. Press the Shift key while dragging to make symmetrical adjustments. The big green rectangle is the combined width handle. Dragging it changes street width and sidewalk width simultaneously.

Street width handles
The StreetWidth handle is shown. Left: When zoomed in, sidewalk and street handles and a combined width handle are shown. Right: Zoomed out, only the combined width handle is shown.

You can set street width parameters numerically as well in the street parameters.