TN 911 Project and Network Analysis

Jun 6, 2023 | 911, QGIS

About 2 months ago I was speaking on the TN 911 database project and did a quick demo and promptly forgot about half of the demo once I walked away from the podium. One thing covered was the network tools in QGIS. 5 years ago (maybe more) I was asked by a local county for help as they didn’t have ESRI’s networking product. I ended up using GRASS to figure it out a 2 and 5 mile drive radius for fire departments. It was pretty easy. Not super smooth but that was more a problem with their data.

Flash forward a few years and the same question came out of my current 911 client’s county and this go around we used GRASS’s network tools with QGIS’s modeling tools. The client was able to pick the fire station to derive the drive distance.

QGIS 3.2X comes out (maybe it was 3.20 or 22) and we have networking tools. This ends up being a great side effect of the TN 911 database. A small county/city/whoever doesn’t need anything more than a data set of roads and starting points (which will be the fire departments). So in this example I have one selected fire station. I have a roads layer that is snapped and continuous. I’m using the Network Analysis Toolbox -> Service Area from Layer tool in qgis.

The one trick is distance – this has to be in meters. 5 miles is 8048 Meters…aaaaand

That fire truck has 44 miles to cover extending 5 miles from the front door. If you run the entire county it takes about a minute.

Again – QGIS. You can have another tool in your toolbox even if you’re running the restricted license stuff.

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