Putting together a state highway map is no easy task. It involves plotting and updating thousands of miles of roads as well as the names and locations of landmarks like cities, parks, colleges and hospitals.
But one state has figured out a way to automate much of that task, which means maps are more accurate and more up-to-date. Missouri is believed to be the first state to draw its highway maps using GIS technology -- a standard for displaying geographic information that can be shared easily -- rather than commonly used CAD ("computer aided design") files, which are more proprietary. Other states are following suit.
“It’s really versatile. It’s correct," said Joe Carter, the leader of the Missouri Transportation Department (MoDOT) team that produces the maps. "With us maintaining 34,000 miles of roadway, that’s the biggest feature on our map, and we like to make sure we are the ones representing that to the public."
Switching to GIS has several advantages.
For one thing, it's a universal format, so it's much easier for transportation officials to pull in data from other agencies within the state, at the federal level and even in other states.
It also makes it much easier for Missouri to fill out the edges of its map: Missouri neighbors eight other states. In the old days, Missouri cartographers had to piece together information from all of those states to build its own map, and each state had its own way of presenting the information. But the GIS files contain geographic information, such as latitude and longitude, that makes it easy to fit the pieces together.
Because it's so much simpler to compile and update the maps, Missouri can print them on demand. Before, the state had to keep up to 4 million printed maps on hand; now it only stores about one-quarter as many.
"When we get reports that they’re running low, I can call the printer and we’ll have another run like that," said Carter.
And because the maps are updated so frequently, any errors can be fixed more quickly. Plus, the easy-to-update format also makes it easier to produce special maps of smaller regions in the state.
Moving to GIS could save states money, according to Carter. Many of them currently hire outside firms to produce their highway maps. But most transportation agencies already have the software they need to produce GIS-based maps. That was the case in Missouri: MoDOT already used a software known as ArcGIS to inventory state roads and keep track of accident locations for safety studies, among other uses. But Carter realized he could use the ArcGIS software to build highway maps as well.
States will still rely on traditional CAD programs for specific projects, such as designing bridges or highway improvements in three dimensions. Products like Autodesk's Map 3D can also incorporate GIS data to give projects local topographical context, showing, for example, how a new road might curve around a hill and connect to an existing subdivision.
But as Missouri has shown, when it comes to cranking out lower-tech two-dimensional highway maps, GIS can be an easier and more nimble approach -- at least, as long as states continue to produce paper maps.
Carter said he’s fielded questions from officials around the country. Delaware, Illinois and Iowa all seem particularly interested in following Missouri’s approach.
“Other states are moving in this direction,” he said. “It’s exploding.”
