Skill Drill: Clip the Roads Layer to the City of Eureka

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 area around the City of Eureka. Navigate to the Humboldt County website. Locate and download the layer containing city boundaries. 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 City of Eureka and the surrounding regions. At this time, Humboldt County referred to these regions as City of Eureka and City of Eureka Sphere in the attribute table. Check for new alterations in the data in case the names in the attribute table have recently changed.

An image of the City of Eureka 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 City of Eureka 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 a one-mile buffer around the City of Eureka
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 your network dataset serves your needs while excluding the remaining roads in Humboldt County from our analysis.

An image of the Eureka Roads clipped in ArcMap.
Humboldt County roads clipped out to one-mile from the City of Eureka.