Procedure
Step 1: Click the Settings button in the lower left and start by entering the Existing Surface in the dialog provided. Either a TIN or an FLT file are accepted as valid surfaces, both of which can be made within the command Triangulate and Contour. For speed, it is recommended that the binary TIN file format be selected.
Step 2: 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. Referring to our drawing above, we could do the full design at once or 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. These must be pre-designed and stored, ready for recall, before executing the Road Network command. 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: Click Process to compute the design. Based on the settings in the above "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. For the profile design for Loop Road and other intersecting roads, it is a good practice to use Calculate Offsets under the Centerline pulldown to compute the station of the intersection on the main road. For Loop Road, those stations are approximately 21+25 and 25+29. Then use Input-Edit Profile to load the Paris Boulevard profile and enter those stations as "Check Stations" in the lower right of the dialog, to compute the design profile at those points (1174.2 and 1158.6 respectively). These profile points can then guide the design of the Loop Road profile. After roads are added to the list, new intersections are found. When you select a road for analysis, it highlights on the drawing in plan view, as shown below.
If you click Edit after selecting 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:
Similar editing dialogs are offered for centerline file design and for template design, in which cases you are dropped into the full editors for those commands (Input-Edit Centerline and Design Template).
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:
The profile transition PVI distance takes the primary road (in this case Paris Boulevard) and extends its template crown slope 50 feet, and then connects to the next PVI on the secondary road. It works on the premise that the main road's template slope must govern. It then inserts a vertical curve of specified length at the new PVI. Since 1/2 of the vertical curve is 25 feet, the actual template slope extension from the main road reaches to 25 feet from centerline. These values, inherited from the main Settings dialog, can be revised for each individual intersection.
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". If you click the "Front-Left" tab, you obtain this dialog:
Two edge-of-pavement alignments are intesecting, and the radius of the intersection, as defaulting from the Settings dialog, can be edited here. That covers the plan view aspect. But these edge-of-pavement points have their own profile as projected out from the governing road profile along the template. You can actually specify a vertical curve length to transition these profiles, and you can click Edit Profile to review these "curve returns" further. Clicking Edit Profile brings you to still another dialog:
By selecting Edit Template Transition, you can shorten or lengthen the transition zone by entering new starting and ending transition stations.
And finally, for any portion of the intersection transition, you can choose to output the centerline and profile for the shoulder pivot points, and the existing and final sections as centered on the pivot points.
Completing West Drive, Front Drive and South Drive leads to the following plan view and 3D view. Note that West Drive's profile should pay attention to the existing profile positions where it intersects Paris Boulevard and also North Road, or else excessive transition effects may occur. Using the Calculate Offsets command and just inspecting the intersect, you can note that it is found at station 194 of Paris Blvd and station 1125 of West Drive. At station 194, using Check Stations within Input-Edit Profile, the elevation is 1224.92. So the goal should be to make West Drive hit near 1224.92 at its station 1125. Similarly, Front Drive should closely match the elevation of Paris Boulevard as it starts and goes north, and South Drive is subject to both West and Paris. 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.
Note that now, with so many named roads and intersections, a scroll bar has materialized in the upper portions of the dialog. 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:
With Road Network, you can directly input all roads and the program will sort out primary and secondary intersection priorities on its own, while providing you the option to edit these assignments within the Edit options within Intersections. The resulting DTM surfaces can then be studied for water flow using the hydrology features of Carlson Civil, cross sections and profiles can be plotted, and total road-related earthwork calculated.
Pulldown Menu Location: Roads
Keyboard Commands: roadnet
Prerequisite: Profile file and template file
File Names: \lsp\eworkd.lsp, \lsp\eworks.arx, scadewrk.dcl