Quick Start: Build a T-Junction Manually

This is part 2 of the Quick Start. Here you turn a straight road into a T-shaped junction by hand — drawing a branch road and joining it to a through road. Doing it manually shows how junctions actually work before you let the Intersection Tool automate it.

Quick Start series: 1. Create a Road → 2. Build a T-Junction Manually (you are here) → 3. Build a T-Junction with the Intersection Tool

Note

Prerequisite: you can already create a road — see part 1. Start from a straight through road (the top bar of the “T”).

The one rule that makes a junction work

A junction becomes a single seamless mesh only when all of its splines live in the same AMetaRoad actor and the same SubGroup — the bake then triangulates them together and fills the junction surface. If the branch is in a different actor/group, it is baked separately and you get seams. Keep this in mind for every step below; the full explanation is in Spline grouping.

1. Select the through road

Select the AMetaRoad actor of your through road so the branch you draw next can be added into the same actor.

2. Draw the branch into the same actor

Activate the Spline tile in the Create palette and draw the branch (the stem of the “T”) so its end meets the side of the through road. When you finish, choose “Add spline to the selected actor” (not “Create a new actor”) so the branch joins the through road’s actor. See Draw Spline Tool.

Tip

Draw straight into the connection. If you begin (or end) the branch on a lane connection of the through road, the Draw Spline Tool uses its Drawing from Lane Successor Connection mode and matches the lane count for you — the lane-level connection is wired automatically. See Draw Spline Tool → Start Drawing from Lane Successor Connection.

3. Connect the lanes

Switch to the Spline tile in the Edit palette (Spline Mode). Here you manage the endpoint connections between the branch and the through road — link the branch’s end connection to the through road so the lanes are joined (see Intersections and Junctions). If you drew straight into a lane connection in step 2, this is already done.

4. Check the group

Make sure the through road and the branch share the same SubGroup (the default empty group is fine as long as they are in one actor). You can confirm/set it in the spline’s Details → SubGroup row.

5. Preview and tidy up

Switch the view toggle to Preview. The junction surface now fills in where the splines meet. Use Section Mode and Width Mode to tidy the lanes and widths around the junction.

6. Bake

Open the Bake palette → Bake Selected on the junction actor. Because all its splines share one actor and group, the T-junction bakes as a single seamless mesh (<YourActor>_Gen). See Baking.

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