qgis basics for journalists

Add roads

It's important for people to have landmarks when reading a map to help them locate areas of interest. Major roads are one of the primary land marks that everyone understands and most maps are incomplete without them.

Roads are line SHP files. The Census includes all roads in a single SHP file. So you'll want to create versions where you isolate just the roads you want so you can access them quickly in the future. They are editied the same way as the boundary layers.

Load the roads SHP file

Go to the Layer menu and select Add vector layer (Command-shift-V). Navigate to the project files and open SHP files - source folder, then the alameda-2010-roads folder and then click on the file that ends in .shp. Click Open. A roads layer will be added to the map.

Make sure the roads layer is selected, go to the Layer menu and select Open Attributes Table. Search for S1100 in the MTFCC column. S1100 is the code for major roads. Click OK

NOTE: Lists of MTFCC codes have been included in the Resources folder in the tutorial files.

Create a major roads SHP file

Go to the Layer menu and select Save Selection as vector file. Save the file in a new folder and call it alameda-major-roads.shp.

Load the major roads SHP file and hide the original by unchecking the box in the Layers panel.

Open the major roads layer properties and change the line width to 1 and change the color to white. Click OK. Your map should look like this:

major roads

Create a secondary roads SHP file

Let's do the same with secondary roads in case we have to do a more detailed map later.

Hide the major roads layer and show the orignial roads layer.

Make sure the original roads layer is visible and selected. Go to the Layer menu and select Open Attributes Table. Search for S1200 in the MTFCC column. S1200 is the code for secondary roads.

Close the attributes window, go to the Layer menu and select Save Selection as vector file. Save the file in a new folder and call it alameda-secondary-roads.shp.

Load the secondary roads SHP file and hide the original by unchecking the box in the Layers panel.

Open the secondary roads layer properties and change the line width to .5 and change the color to white. Click OK.

Your map should look like this:

secondary roads

The original roads SHP file contains about 10 types of roads, including city streets, fire roads, etc. You could extract each road type but that's more than you'll need on a regular basis.

Click the original roads layer. Go to the Layer menu and select Remove Layer (Command-d).

Save your work.