Carlson RoadNET: Workflow Example
Step 1: Start New Road Network
Start the Road network command. If you have previously run Road Network with the current drawing, the Road Network docked dialog will open with the last Road Network (.RDN) file you worked with. If this happens, but you prefer to create a new Road Network (.RDN) file, click the Load/New button at the bottom of the Road Network docked dialog.
Step 2: Add Roads
Back in the main dialog, click “Add” in the upper left “Road Name” portion, and identify all of the main road and secondary (intersecting) road centerlines. For this example, we will start by identifying North Road and East Road as the main roads and Paris Boulevard as the first secondary road. Note that centerlines may be picked as polylines or loaded as centerline files. All centerlines (horizontal alignments) must have, at minimum, an associated profile (vertical alignment) and an associated template. In the Road name dialog portion, select a road and click Edit to review the files. Note that by selecting Paris Boulevard and East Road, the program automatically detects the first intersect. As you follow the design below, you will see that we follow the hierarchy of the road precedence as outlined in the graphics. At every intersection, there needs to be a primary controlling road (template cross slopes are held) and secondary adjusting road (centerline profile adjusts to template of primary road at some transition distance).
Step 3: Process, Review and Add more
Click Process to compute the design. With the Triangulation option enabled under the “Settings” dialog, the program will Triangulate and Contour and create the drawing shown below. If you edit any road feature or dialog entry and click Process again, the program automatically clears the last Triangulate and Contour drawing and creates a new final design drawing. In this way, you can trial-and-error your design for all roads, or build the design in stages.
Viewing the file in the 3D Viewer Window command with a 4.0 vertical exaggeration, you can even see how the curb-and-gutter Paris Boulevard ends abruptly as it transitions to the roadside ditch template of East Road.
Next we can review the effect of adding Front Drive, Loop Road and West Drive into the equation. If you click Edit after adding Loop Road as above, you have the option to change any aspect of the centerline, profile or template file, and you can add optional files such as road width change files and superelevation files. For example, if you choose to edit the profile, the program derives the existing grade from the existing surface triangulation file specified in Settings, and you are able to design graphically and interactively as shown:
You can also more closely analyze the intersections of any road. If you select the intersection at ParisBlvd and Start:LoopRd, you obtain the multi-tab dialog:
Since we do not have a crossing intersection, we only obtain a “Front-Left” tab and a “Back-Left” tab, left being the left side of the primary road (Paris) and front being the first “curve return” treatment on the outside of the loop and back being the second “curve return” treatment on the inside of the loop. If this was a crossing intersection, you would have 2 more tabs in the dialog: “Front-Right” and “Back-Right”.
Completing West Drive, Front Drive and South Drive leads to the following plan view and 3D view. Clicking Add within the Cul-de-Sac portion of the docked dialog enables you to specify at cul-de-sac at the end of South Drive.
Clicking Process now produces the following:
A close-up view of the cul-de-sac, in 3D, reveals the detail of the design, showing a raised “fold” due to no vertical curve transition at the projected high point at the back of the cul-de-sac:
This dimple effect can easily be eliminated by lowering the elevation of the “PVI” at the projected intersect point in the back of the cul-de-sac, and by adding a vertical curve transition of, say 50′. This is done by highlighting the South Drive Cul-de-Sac and clicking Edit.
Clicking Edit on the selected SouthDr at End cul-de-sac leads to this dialog:
The first thing we do is change the Profile Transition VC from 0.0 to 50.0, as shown. Then we need to click Edit Profile to lower the profile at the back of the cul-de-sac. This profile refers to the edge-of-pavement grade.
Now, after clicking Process, the cul-de-sac has a better design:
Pulldown Menu Location: Roads → Road Network
Keyboard Command: roadnet
Prerequisite: Existing Ground Surface (.TIN) file, Template (.TPL) file