GPS has made our lives easier in many ways, from just being able to know exactly where you are on the planet to being able to get directions in seconds to nearly any destination. For everyone who uses it there has probably been a time where you questions the route that was given to you by your device. Why is it that your GPS device can be wrong and what can you do about it?

But GPS Told Me To Go This Way

Here in South Central Pennsylvania we see a lot of trucks. We also have a lot of bridges that are not high enough for a truck to go under. There is one here in York County near Seven Valleys. There is are several in Lancaster, like a covered bridge at Schenk’s Mill that a tractor trailer got stuck in in 2018. When something like this happens it causes potentially thousands of dollars in damage and leads to a great deal of inconvenience for a lot of people. When asked why the truck drivers drove that route they almost always say one thing: their GPS told them to.

Of course truckers are not the only ones who do this. Numerous drivers have driven into lakes or any other place that a vehicle should not go. When asked the driver says that their GPS told them to and it can have deadly implications. Almost as tragic as all of the people who died playing Pokemon Go. Turn by turn directions change inexplicably or you get sent down a street that is not lit at night or down a smaller street when a more viable avenue is nearby. Locals may be able to overcome this but not everyone is a local.

Why does this happen? The answer to that can be extremely complicated or it can be very simple. 

A Brief Overview Of GPS Tech

GPS is a complicated technology. In low-Earth orbit 12,000 miles above our heads are 24 GPS satellites. These satellites send radio signals down to Earth that communicate with devices that can receive them, like a GPS device like in your smartphone. To determine your location on the planet several of these must be in communication so the location can be triangulated by determining the amount of time it takes for that radio signal to arrive and come back.

Of course on your device is a map. These can be downloaded onto the device or available in real-time from the Internet. This can include the street map, points of interest and other information. Traffic information can also be updated in real-time and streamed over the Internet. 

Your GPS device handles a lot of information in real time. From constant triangulation to new points of interest and new traffic information there is a lot that goes on behind the scenes. There are a lot of pieces that need to work together at just the right time to make GPS work correctly. Sometimes one piece of this intricate puzzle is not working.

What Can Make The GPS Stop Working?

There are also physical issues that can prevent a GPS unit from working. Weather is perhaps the most common as something as simple as clouds can obscure a transmission much less rain or snow. Natural landmarks like hills or even forests can also do the same thing. So can human-made things like tall buildings. When a transmission is garbled your GPS unit will not be able to work the way it was intended and you may get a new route when it reconnects. If your GPS takes into account real-time traffic and a situation may have changed your unit will update the directions to take that into account as well.

There are other reasons as well and they can be much more simple. How well your GPS unit works is tied to how good your receiver is. If your unit is older it may not be as good, especially when compared to modern receivers, which can usually place a person within 50-150 feet of their actual location. Part of this has been mitigated as wi-fi hotspots and cellphone towers have begun to assist in geolocation but it is not perfect.

Not All Information Taken Into Account

When it comes to your route there are a lot of factors that go into determining it. If you drive down a typical road you will notice that it has curves and turns on it. The speed limit may change, several times in fact. The algorithm used may not take everything into account when calculating a route like those speed limit changes or having to slow down for curves. The computer may not know that the speed limit drops from 45 to 25 to go around a long curve or it may not be able to take into account how long a traffic light lasts. 

That is why a local may still have the best route. It’s not that they are smarter, they just know the lay of the land.

Mapping Software

Most mapping software comes from one of two places, either Tele Atlas or Nokia. This software is licensed to companies that want to use them. Apple and MapQuest use Nokia’s software. Some use both. This can lead to perhaps the simplest reason that your GPS might send you the wrong way, the map has something wrong with it. That could be that a new location, street or road has not been added or that a street has been closed, either permanently or temporarily. 

Street closures cannot always be updated. Some work may only take one or two days to complete and thus it is not worth it to update GPS maps. Or perhaps no one ever informed the mapping software and since they don’t know, you won’t know.

How Can GPS Be Better?

So how can GPS be made better? Did you know that you can submit GPS corrections directly to the government? You can. If your business is located at the wrong place on the map or directions send people the wrong way, vist and submit a correction. For truckers, use a special Truck GPS and avoid driving under low bridges or through places that your truck won’t fit. You can also avoid roads or highways where your truck is not allowed to go. It may be a bit more expensive but when compared to the fine that comes from any of the above, it will pay for itself.

The next time your GPS changes your directions know that there can be a number of reasons why and it’s not always bad. It can be fun to take a different route and force your GPS unit constantly recalculate your route. It can also be fun to see if you can drive the route faster than your GPS unit says it should take (don’t speed though!). But it can also be frustrating when it changes routes and sometimes it is good to be a local and know your route home. Or to have an idea where you are going and not completely rely on GPS. Technology is taking away the ability to read a map and that is a useful skill that everyone should have.

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