Overlapping routes are defined as routes that share roadbed. These may also be called shared routes, coincident routes, or concurrent routes. It's important to distinguish between overlapping routes and routes that only appear to overlap, because events must usually be tied to a specific section of pavement. When you realign or retire a portion of a route that overlaps with another route, it is quite common that the actual pavement didn't change.
Event data such as speed limit or functional class is really only relevant to that particular section of pavement, not necessarily the route it happens to be assigned to. When you remove a route identifier from a section of pavement that is also associated with another route, you need to determine what happens to the events. If you want the events to snap to the remaining route, Esri Roads and Highways must know that this is an actual overlap.
Roads and Highways does not automatically identify overlaps when routes are created. This is because not all highways that happen to share the same geographical space horizontally also share the same space vertically. Elevated causeways, stacked bridges, and freeway interchanges are some examples of roadways that may appear to be coincident but are actually completely different roadways.
Because it's easier to add overlap conditions than it is to remove them, Roads and Highways supports the assignment of overlaps as a part of the workflow. Once you create a route, the next step in your workflow is to assign any overlap sections. Roads and Highways is smart enough to help you figure out where these might occur, but the actual assignment is up to you.
The Assign Overlaps tool can be found on the Roads And Highways Editing toolbar.
Start ArcMap and start an edit session.
See Setting up the Roads and Highways editing environment for more information.
- Zoom to the area where you want to assign an overlap.
- Choose an LRS Network to edit by clicking the Networks drop-down arrow on the Roads And Highways Editing toolbar.
- Click the Assign Overlaps button on the Roads And Highways Editing toolbar.
The Assign Overlaps dialog box appears.
- Enter an effective date, route ID, and from and to measures for the overlapping route.
You can use the Spatial Selection tool to select routes and measures from the map. This is especially useful if you have a long route and are only interested in assigning overlaps to a small portion.
- Click the Add Candidates button to add a list of candidate target routes.
- Click either the Use Overlap Geometry or Use Target Geometry button.
Choose overlap geometry if the centerline features used to create the overlap route are considered better than the centerline features used to create the target routes. When assigning overlaps as part of the create route workflow, you should use the new route as the overlap route and any existing routes as target routes. Then, when you choose to use the overlap geometry, you will know that you are using the most current, and probably most accurate, geometry for constructing the overlapping routes.
- Click OK.