Gas
How a gas utility uses GIS
The map is the record of mains, services, and what the crew last installed.
A gas company has pipes in the ground that people cannot see. The map is how the company remembers what is there.
The big pipes are mains. They run along streets. Smaller pipes leave the main and go to a house or a business. Those are service lines. The map also shows valves, meters, and regulator stations. Each one is a point or a line with facts on it.
Before a crew digs, they look at the map. They need the location, the material, and the size. Steel and plastic are not the same job. An active pipe and an abandoned pipe are not the same job.
After the crew finishes, the map has to change. If they replaced a service, the old record is no longer true. Someone compares the crew’s paperwork to the map and then updates the line. That paperwork is often called a field packet. The drawing of what was actually built is the as-built.
GIS is also how the company answers ordinary questions. How many services are on this street. Which mains are steel. Which jobs are still waiting on a map update. Those questions are lookups. They only work if the attributes are filled in the same way every time.
A gas map is not a driving map. It does not need to look pretty. It needs to be specific. The person who posts the change and the person who digs next year have to be able to trust the same line.