Skill Drill: Clip the Roads Layer to the City of Arcata and McKinleyville

Network analysis can place significant demands on a computer’s processing power and memory. To save time during the analysis, you will need to constrain the road network to the areas serviced by the Arcata Fire Protection District. Navigate to the Humboldt County website. Locate and download the layer containing fire districts and response areas. Decompress the file into your original folder. Check the spatial reference system. If necessary, use the Project tool to create a copy of the data with the NAD 83 UTM Zone 10 spatial reference system. Add the layer with the correct spatial reference to your Table of Contents. Create a layer based on the areas related to the Arcata Fire Protection district. At this time, Humboldt County designates these areas under the Agency field in the attribute table.

An image of the fire districts selection in ArcMap
A temporary selection layer created from the selected features. You can export the data to create a permanent shapefile if desired.

Some roads may extend just outside of the Arcata Fire Protection District and related regions. To prevent altering the geometry of the road segments needed in our analysis, create a one-mile buffer around these areas.

An image of the Fire Districts buffer in ArcMap
A one-mile buffer around the selection layer created using the Buffer tool.

Clip the roads layer and use the buffer as the clip feature. This clip operation ensures that our network dataset serves our needs while excluding the remaining roads in Humboldt County from our analysis.

An image of the roads clipped to the buffer.
Humboldt County roads clipped out to one-mile from the Arcata Fire Protection District.