I ran in to all sorts of problems with Google Maps and Waze navigating me in the UK.
Google Maps cannot understand that just because a road's speed limit is theoretically 60 mph, doesn't mean it's ever possible to travel at that speed on that road. So it would keep sending me down little tiny narrow twisty, single lane country roads that you're rarely ever going to break 20mph on.
I grew up driving those roads, so in general I was fine and comfortable driving on them, but it did mean that it was sending us on the slowest possible route.
The only time it'd not try to do that was if enough people had been down in recent enough time for it to think the road was suffering from heavy traffic. There's no way to actually indicate to Google the nature of the roads, either.
It always struck me of being very indicative of a US centric perspective, written with the assumption that roads are wide and open.
edit: It has been something like 10-15 years since I last used a TomTom GPS unit in the UK, but I never had problems with them sending me down narrow roads.
I don't know how Google Maps works (I quit paying attention when they stopped letting me fix the maps directly), but I know a thing or two about Waze.
With enough use, Waze learns the actual speeds at which people drive through a given road segment. It even learns that people may drive a segment at different speeds based on time of day. It then uses this speed data as part of its routing.
The emphasis above is very intentional, for two reasons:
1. No data is no data. If there isn't enough use on a given road segment, then it doesn't have any meaningful speed data with which to work. This is particularly problematic in rural areas that are seldom-traveled, and where the locals already know how to get where they're going so they seldom (if ever) use Waze (and thus generate little or zero real-world speed data for Waze to work with).
2. We may have our preferences towards "fastest" or "shortest" routing, but the actual-routing is not that straight forward. Depending on the area, there may or may not be different road types defined by map editors (things like "Primary Street" or "Minor Highway"). The routing tends to guide people onto more-major roads when they make sense for a given route.
2.1. But again, no data is no data. In areas where these definitions have not been put into place, it doesn't have the data to allow it to prefer routing down a nice, wide, straight-ish road instead of a narrow and twisty road.
---
Now, there are some solutions to these things:
1. Drive the crazy route. Drive it sanely, but drive it with Waze running (it does not have to be providing directions). This generates data, and that data can eventually help those who come after you. (Many people have serious issues with partaking in this kind of effort, but this is the mechanism by which the database gets populated with speed data regardless of one's views.)
2. Edit the map. Follow the national and regional guidelines, make good edits, and fix that shit. (Many people have serious issues partaking in this kind of effort as well, but this is the mechanism by which road types are defined regardless of one's views.)
Google Maps cannot understand that just because a road's speed limit is theoretically 60 mph, doesn't mean it's ever possible to travel at that speed on that road. So it would keep sending me down little tiny narrow twisty, single lane country roads that you're rarely ever going to break 20mph on.
I grew up driving those roads, so in general I was fine and comfortable driving on them, but it did mean that it was sending us on the slowest possible route.
The only time it'd not try to do that was if enough people had been down in recent enough time for it to think the road was suffering from heavy traffic. There's no way to actually indicate to Google the nature of the roads, either.
It always struck me of being very indicative of a US centric perspective, written with the assumption that roads are wide and open.
edit: It has been something like 10-15 years since I last used a TomTom GPS unit in the UK, but I never had problems with them sending me down narrow roads.