Hi, This is sort of my problem in Chicago on the Dan ryan highway, one specific spot every single day. I understand the GPS restrictions about not knowing what lane you are in if you are only a few lanes off of the original decision of the app. The GPS situation is solely a limitation of the device and not the app. My Problem is with the timing of the decision the app makes to go Local or Express before the "split" in the road. Its changes its mind in either direction everyday (almost) to late for me to safely make the move. How do I get you more detail? I submitted my issue via the App but I couldn't find an easy way to continue the conversation, thanks, Todd

Yeah, that’s really bad. Especially since it can clearly tell no problem when it’s not following a route. Can I send feedback to Waze somehow about this? Do they read this board?

Stopping and restarting the route is insufficient in my experience as it sticks with its assumption. You actually have to either stop the routing *before* the split or actually kill the app, neither of which is particularly safe during driving.

Thanks for the link. I will make my concern known to them.

I happen to work with GPS for a living and while there are a lot of factors, you’re greatly understating it’s accuracy. Surveyors typically consider it accurate to a few meters. Here it is straight from the US govt:
“For example, GPS-enabled smartphones are typically accurate to within a 4.9 m (16 ft.) radius”
Source:
https://www.gps.gov/systems/gps/performance/accuracy/

300ft sounds more like 90s level accuracy when the government was (openly) intentionally degrading the signal. In fact it wasn’t that bad even then:
Source: https://www.gps.gov/systems/gps/modernization/sa/data/

If that was true, it wouldn’t get it right every time when I took a fork in the road without guidance on. Or it would often show me on the other side of an intersection when I was stopped at a light. Or many other errors that just don’t happen.

GPS isn’t accurate enough to say for sure what lane you’re in, but if you’re in the left lane of a 3 express roadway, it sure is accurate enough to know you’re not in the local lane.

Thanks again for the link.

Hi Todd, could you send a permalink of the exact location in which you are referring to? I would be happy to help make some adjustments

Hi Fredct42,

When you have close parallel roadways like Express/Local, Waze just assumes you're in the roadway it directed you into. Our recommendation is to always follow the directions given - for the most accurate directions. If that's not possible for any reason, you may have to stop your route to force the app to recalculate your GPS position and recalculate a new route to get directions for the other roadway.

Happy wazing.

Unfortunately, the issues lies within the error limit of consumer GPS chips. And this is a known limitation with all GPS apps.
Given that many things can interfere with a clear signal, including coatings within vehicle windshields, the presumed accepted error is about 300 feet. Clearly there are few places in NJ where parallel roadways diverge farther than this distance! (A standard US Highway lane is 12 feet.) The GW Bridge is a gigantic metal Faraday cage that severely impairs GPS reception - we get reports of routing errors for people who *did* follow the recommended route there.

Quite frequently stopping the route, or simply opening the lower menu and using the "routes" option will force a recalculation that picks up your true location. Given the limitations of GPS tech, this may not always happen.

Our recommendation, as volunteer map editors, is that you follow the suggested route for the most accurate instructions. Waze is designed to find the fastest course from Point A to Point B, and this might not be the most scenic. It's up to the driver to make sure the maneuvers needed are safe.

If you wish to give feedback to the development team (Waze Staff) you can use this form: https://support.google.com/waze/answer/6276841

Thanks!

Yes, in perfect conditions gps-enabled smartphones can be accurate to a 16 foot radius.
Unfortunately many things can interfere with accuracy, as I stated.
So as far as the Waze Map Editors are able to discern (Waze keeps plenty of things secret!) the accepted accuracy used to figure out when to recalculate seems to be about 300 feet.
As for your intersection example, the software must be doing a fair amount of inference to a) keep from recalculating frequently and b) keep you on the right side of the intersection when stopped at a light.

BTW - I know all about Selective Availability and it's removal on May 2nd, 2000.

62b68e229bd4457fa0dd50c54be88550 wrote:... This is sort of my problem in Chicago ...

Todd, in that case it sounds like the split point *might* need to be moved. One of the Chicago-area editors should come across your User Report soon, but you could post in the Ilinois forum in the Great Lakes Region section. It's unlikely an editor from that area is following the NJ forum, so I'll see if I can raise one of them in our editor chat server and let them know you're looking at an issue.

-Greg

The best thing to do for the express/local problem - especially in places like the GWB or NJ Turnpike, where a less than accurate route can lead to the opposite turn instruction from what you need, because of the way the roads are configured - is once you get into the roadway you want to take, stop your trip in Waze and then re-navigate to the same destination, which you should find at the top of your recent destinations list, right?

We know it's just a workaround. To be clear, it's not so much a limitation in the accuracy of a single GPS position. Waze can tell exactly where you are to a matter of inches when you're starting a route, for example, or when you're submitting a report, etc. The problem is that as you drive down the road, your trace of GPS points isn't always a straight line because of a phenomenon called GPS dither, caused by a variety of things that we have no control over as we drive. To prevent this dither - which can occur momentarily at random - from causing excessive recalculations and eating up both server resources and your data, thresholds were set for how far off-course you have to be before Waze considers needing a recalculation. Unfortunately, to prevent excessive recalculation when you are on the correct road, the threshold had to be set to a level that often makes automatic recalculation ineffective between express/local roadways. It's further compounded by the backwards directions it results in on at GWB and on NJ Turnpike, so hence the workaround I mentioned above.