Intersections
An Intersection represents the area where two or more roads meet and connect.
Intersections can be created using the Civil 3D Intersection Wizard or manually, provided the same geometric and profile principles are followed.
Supported creation methods
Intersection Wizard (recommended): uses offset alignments and dynamic curb return profiles.
Manual: allowed if the same geometry + profile linking rules are respected.
Prerequisites
Corridors exist for the intersecting roads, built with regions.
Each centerline alignment has an Existing and Design profile.
Corridor vertical baselines are set to use the Design profiles.
If not, curb return profiles may not maintain links to offset alignment profiles when vertical baselines change.
Requirements
Side road rules must be disabled. (Fundamental)
Offset alignments and offset curb returns must be used (Feature Lines are not supported for defining curb returns).
Curb return subassemblies: use the “Gutter Edge” insertion point when creating intersections manually (Civil 3D default).
Lane subassembly required on curb returns
Feature Lines are not supported to define curb returns.
Curb returns must have a 'lane' subassembly, this extends mesh lines towards the target alignment. In the future support will be added for this type of curb return / cul-de-sac.
Corridors that do not use intersections / connected alignments and do not have curb returns are not currently supported (ie where feature lines are used to manually set levels around intersection). Support will be added 2026.
Profiles
Having created the corridor and intersections with the design profiles as vertical baselines will allow Level AI to update the design profile automatically without needing to update the profiles used by intersections.
Allsite does not support Secondary/Side Road Profile Rules. Before running Level AI results for the first time, the rules must be disabled for every intersection. This is because Level AI is automatically grading the roads at these tie-ins between roads and the extra points added can distortion the design. How to disable Side Road Profile Rules.
