Slip Road Tool

Slip Road Tool button

The Slip Road Tool is used to create onramps, offramps, and road splits.

When using the Slip Road Tool, a light blue circle follows the pointer. This circle snaps to lanes and the lavender road node lines at the ends of roads.

Different actions occur depending on which objects you select, the locations where you right-click, and whether you are pressing the Shift key.

Create a Single-Lane Onramp or Offramp

  1. Click the Slip Road Tool button.

  2. Move the pointer over the outermost driving lane of a road. The light blue circle gets slightly larger.

  3. Right-click and drag to show a preview of the slip road to create. This action forms either an onramp or offramp, depending on whether you are dragging ahead of the starting point or behind the starting point.

  4. Release the right-click button to create the road.

Tip

If you release the right-click button on another road, the new road is a slip road at both ends. For example, it could be an offramp for the first road and an onramp for the second.

Junctions are automatically created whenever multiple roads overlap, including in slip road cases. Refer to Junction Tools for more information on working with junctions.

For example, you can use the Corner Tool to adjust the geometry of the curve between the ramp and the main road:

Junctions involving slip roads still contain maneuver roads (see Maneuver Tool). The automatically-created maneuver roads are not guaranteed to match the expected connectivity. It is recommended to double-check maneuver road topology in slip road junctions as you would do with an at-grade intersection. This is important to ensure that the lane connectivity is correct when exporting to a format like OpenDRIVE®.

Create a Multilane Onramp / Offramp

  1. Select the Slip Road Tool.

  2. Move the pointer over the innermost driving lane that you want to connect to the ramp. The light blue circle gets slightly larger. This lane and all lanes up to the edge of the road will connect to the ramp.

  3. Right-click and drag to show a preview of the slip road to create. This action forms either an onramp or offramp, depending on whether you drag ahead of the starting point or behind the starting point.

  4. Release the right-click button to create the road.

Note

By default, the driving lanes between the selected lane and the edge of the road end at the new junction. That is, in an offramp case, these lanes are dedicated offramp lanes that do not continue along the main road. If you hold the Shift key when you release the right-click button, this behavior is disabled and all driving lanes continue along the main road.

Create a Road Split

You can split a road into two roads by creating slip roads at the end of a road.

  1. Click the Slip Road Tool button.

  2. On the lavender road node line at the end of a road, move the pointer over the innermost driving lane that you want to connect to the new slip road. The new slip road will include this lane and all lanes up to the edge of the road.

  3. Right-click and drag to show a preview of the slip road.

  4. Release the right-click button to create the road.

You can optionally provide more fine-grained control over the lanes to be included in the slip road. This is useful for creating more advanced types of road splits.

Before following the steps above, select a range of lanes on the lavender road node line. The created slip road will connect to the range of lanes defined by the innermost and outermost selected lanes.

Create a Channelized Turn Lane

You can also use the Slip Road Tool to create physically separated, branching lanes in any situation.

For example, you can create a channelized right turn lane on an at-grade intersection. Follow the steps to create a single lane or multilane ramp on a road leading up to an intersection. If you end your drag on the crossing road, it will create a channelized turn lane.

Adjust Where a Slip Road Is Connected

You can adjust where a slip road is attached to the road at its ends:

  1. Select the Road Plan Tool.

  2. Click and drag the dashed lavender road node at the end of a slip road.