How to Fix Map Errors on
If you're having problems with information displayed by car navigation systems or handheld personal navigation devices -- wrong addresses, missing location names, closed highway exits, etc. -- it's likely you're experiencing a mapping software issue, not a problem with the Global Positioning System (GPS).
GPS Helps You Get Your Coordinates
GPS satellites are much simpler than most people think. They cannot track you. They don't have comprehensive map databases like Google Earth. In fact, they have no knowledge of anything on the ground.
GPS satellites are just beacons, like lighthouses, that tell you where they are in space. They do not tell you where you are. Your navigation device uses the satellites as reference points to determine your coordinates on the Earth in terms of latitude, longitude, and altitude.
Of course, raw coordinates are useless without a map. The earliest GPS receivers did not have built-in maps, so users had to plot their coordinates on paper maps to navigate. Only in recent years has the technology existed to include digital mapping features in affordable navigation devices. Even today, many GPS units don't come with maps -- for example, tracking devices used on prisoners and animals.
Who Provides the Maps?
The maps and other information about roads, addresses, businesses, etc., are loaded onto consumer navigation devices by the commercial companies that manufacture them. The U.S. government's GPS program does not provide any of this data.
Most manufacturers get their digital maps and data from commercial map makers (or digital content suppliers), the largest being NavTeq and Tele Atlas. Some device manufacturers develop their own maps.
In addition to maps, many navigation devices offer features such as route suggestions, traffic alerts, and voice announcements of turns and street names. These extras are provided by the device manufacturers and have nothing to do with the GPS satellites.
Why Are My Maps/Routes Incorrect?
If your navigation device says you are driving off-road when you aren't, it's possible your GPS coordinates are correct, but your device is drawing the road incorrectly.
Some information in your navigation device may be based on older maps prepared before the era of GPS precision. Also, maps require constant updates to stay accurate. Roads continually change due to construction, temporary detours, etc. New housing developments and business parks appear every week. And restaurants and stores are always opening, closing, relocating, or changing names.
Even a brand new vehicle with an installed navigation system could have outdated map information if, for example, it sat at the dealership for a few months before you bought it. If you do not install the latest maps or subscribe to an update service, your navigation system will fall even further behind the times.
Another cause of map errors is the software that approximates the location of street addresses. For example, say you live at 150 Main Street, next to a large property that occupies two-thirds of the block. Lacking a plot-by-plot map of your neighborhood, a navigation device may assume your home is halfway up the block, leading delivery trucks to the wrong location.
Devices providing route assistance need both their maps and software to be up to date, or they may make bad suggestions, such as taking a dirt road through someone's private property.
In any case, homes and businesses are required to have their addresses clearly visible from the street. More importantly, drivers are still responsible for observing posted road signs and using common sense.
What Can I Do To Fix Map/Route Errors?
The first thing to do is find out if there is an updated map available for your device. Most navigation device makers charge a fee for map updates, but some offer one update for free. Some also offer free access to user-submitted map fixes. Review your user manual and contact your device manufacturer to learn the best way to update it.
If your device is up to date -- or you are concerned about errors on other people's devices -- you can report the problem to the digital content suppliers. It usually makes sense to submit the same correction to both NavTeq and Tele Atlas. Their websites allow the public to submit map corrections. The following links are provided for informational purposes only; the U.S. government does not endorse any products, services, or views found on external sites.
Some navigation devices allow users to enter map fixes directly on screen, then upload them to the manufacturer and/or other users when connected to the Internet.
Once you submit a map or route correction, the content providers typically verify and implement it through a map update. This can take weeks, months, or years, depending on the provider. The change won't show up in your device until you download and install the update. Likewise, it won't show up on anyone else's device unless they also apply the update or buy a brand new device.
This story was originally published in May 2011. We made minor text edits in November 2011.