Road Location with GIS
Updated August 09, 2021
This article applies to:
- RoadEng Civil
- RoadEng Forestry
This example illustrates how to apply the Location design module to GIS data for route selection.
A shape file with contours will be imported and assigned elevations. A terrain model (TIN model) will then be created and used for topography in Location design.
Note: The files used in this example can be downloaded here: RoadLocationGIS.zip
Importing A Shape File
1. Open the Terrain module. Select File | Open. From the Files of Type drop down menu, scroll down to Arcview SHAPE (*.SHP). Select Contour.shp (included with this example).
2. An import Options dialog box appears. Under the Options tab ensure that “Include Attributes” and “Add Themes to Layer Table” are enabled. Press OK to open the file.
3. The scale is set at 1:5000 and too large for the plan window. Press the Zoom Extents button to adjust the image to the screen. The Contour Shape file will now appear as shown Figure 1 below.
Figure 1: Contour Shape File
Creating a TIN Model
Most shape files are 2 dimensional, elevation values are often saved as attributes. You can determine if a shape file is 2D by clicking on contours and examining their elevation. In this example, the elevations are all 0 after import, indicating the file is 2D. Select any contour line in Plan view; note the elevation in the status window.
To create a TIN model you must have elevations. For this example, elevations will be extracted from an attribute ( XCONTOUR_ ).
4. The first step is to select all features displayed in the Plan Window. Click on Home | Select | All Feaures. Note that all features are now displayed in Magenta.
5. The second step is to modify the selected features by properties. Choose Feature Tools | Feature Properties. Ensure Elevations and Modeled are enabled.
6. The third step is to add XCONTOUR as the elevation value attribute. Select Features Tools | Assign. The Assign dialog box will appear. Enable the Attrib radio button in the Z row. Then click on the Attrib button (on the right hand side of the Z row).
7. An Attributes dialog box appears. On the available side, scroll down to Contours. Double click to open the contours folder. Add XCONTOUR_ to the Selected List. Press OK. The Assign Dialog box should appear as shown in Figure 2. Press OK.
Figure 2: Assign Dialog Box
A TIN model will now be created from the contours.
8. Select Terrain Modeling | Generate. Set the parameters as shown in Figure 3. Press OK to create a TIN model.
Figure 3: Terrain Calculation Dialog Box
9. Save the Terrain File as “Contour.terx” and choose menu Module | To Location Design.
Creating a Location Design from a TIN Model
The hard work has now been done and you can now create a new Location design based on the TIN model (Contour.terx). This will allow you to place the road centerline (c/l) anywhere on the Terrain model and the topographic cross sections will be automatically calculated.
10. Open the Location module. Select File | New. Choose file “Contour.terx”. When the New Location Dialog box appears choose “Center of Terrain” and press OK. Minimize the profile Window. Press Zoom Extends button .
You are now ready to begin designing the road. The remainder of this example assumes the reader is familiar with the Location Design module. Only brief descriptions of the steps are provided.
The first step is to set out the horizontal alignment (without considering the profile).
11. Maximize the Plan Window, right click and select Add/Edit IP tool. Move the cursor over the red cross displayed in the center of the Terrain. The cursor will change to an Edit cursor shape. Left click to capture the point. Move it approximately to the position shown in Figure 4.
Figure 4: The first horizontal alignment point
12. Zoom In and create several new IP points approximately as shown below in Figure 5.
Figure 5: IP Points
13. Select Corridor | Operations | Auto Generate. Choose Fixed Intervals, Spacing: 10 and Point Types: Report as shown in Figure 6.
Figure 6: Auto Generate
14. To create a vertical alignment, maximize the Profile Window and create a vertical alignment as shown in Figure 7.
Figure 7: IP Points
This will be the stopping point for this example. It covered how to create horizontal alignments directly from a GIS topography file. Adjusting the design, viewing cross sections, calculating volumes and mass haul is covered elsewhere