Google Maps for navigational guidance - the good, the bad, and the ugly

[webny99]

A spin-off from the well-known thread on the many technical problems with Google Maps, with a throwback twist.

What are some of the pitfalls of using Google Maps for navigational guidance? What are some cases where you have outsmarted Google Maps for getting from point A to B, or found a better route by simply eschewing recommended routings altogether?

I mostly use Google Maps as a reference for current traffic conditions and to help choose between different alternate routes, rather than strictly as a tool to give directions. In my opinion, blind faith in Google Maps (or Waze etc.) is often misguided, especially when it comes to local trips.

One such example is knowing the timing of signal cycles. I can think of a whole bunch of examples of "if you make this light, go straight, but if you miss it, then turn right (or even turn left, if there's a leading protected phase!). Or "traffic is heavier than usual, so take this alternate instead of waiting for multiple light cycles". Or even simply "avoid this perpetually congested intersection if it all possible" (ahem). All of these are things that Google Maps may attempt to factor in to their recommended routings, but simply can't attain the same level of nuance or precision as an experienced local driver.

[Max Rockatansky]

A lot of Google Maps estimates by me are fouled up given the software doesn't under the basic speed limit in mountains is 55 MPH.  Google will tell me it is often about 10-15 minutes less to take CA 152 to Monterey from Kings County over CA 198.  The reality is that CA 198 is actually the faster route by about 5-15 minutes in regular traffic.

[kphoger]

One pitfall has been the rare occasion that Google thought I couldn't drive directly between two connected segments of road for whatever reason.  Sometimes it's because one-way and two-way movements in an interchange aren't assigned correctly, but other times the disconnect is in some random spot along a straightaway in the middle of nowhere.

Or there are these ridiculous directions for walking from Laredo to Nuevo Laredo, because it doesn't know how to just route you over the bridge.  (If at some point this no longer looks ridiculous, it's a 50-mile detour to the Colombia crossing.)

[webny99]

A lot of Google Maps estimates by me are fouled up given the software doesn't under the basic speed limit in mountains is 55 MPH.  Google will tell me it is often about 10-15 minutes less to take CA 152 to Monterey from Kings County over CA 198.  The reality is that CA 198 is actually the faster route by about 5-15 minutes in regular traffic.

The question would be is maintaining 55 mph actually achievable for all vehicle types on the mountainous parts of CA 198? Google may think it's not even if it is... and having prior experience driving the roadway definitely helps your case. I'm typically 85th percentile or faster driver but I'll be the first to admit I'd be hopelessly inconsistent driving a road like CA 198 from Coalinga to San Lucas for the first time.

[webny99]

One pitfall has been the rare occasion that Google thought I couldn't drive directly between two connected segments of road for whatever reason.

Oh yeah, that reminds me, I've been meaning to find out whether this is still drivable. It's now signed as a dead-end from both ends and Google also shows a gap, but I'm not sure what happened or why.

it doesn't know how to just route you over the bridge

This is also true for the Whirlpool (NEXUS-only) bridge in Niagara Falls, for obvious reasons. To use Google Maps for directions via that bridge, you have to set the near side of the bridge as your destination first, and then set your final destination after you've crossed. Talk about first-world problems!

[Rothman]

Reading like a duplicate of the other thread.

[LilianaUwU]

Google Maps thinks I walk like a grandma. Yes, this destination that is 30 seconds away from me can only be reached in about 2 minutes!

[Max Rockatansky]

A lot of Google Maps estimates by me are fouled up given the software doesn't under the basic speed limit in mountains is 55 MPH.  Google will tell me it is often about 10-15 minutes less to take CA 152 to Monterey from Kings County over CA 198.  The reality is that CA 198 is actually the faster route by about 5-15 minutes in regular traffic.

The question would be is maintaining 55 mph actually achievable for all vehicle types on the mountainous parts of CA 198? Google may think it's not even if it is... and having prior experience driving the roadway definitely helps your case. I'm typically 85th percentile or faster driver but I'll be the first to admit I'd be hopelessly inconsistent driving a road like CA 198 from Coalinga to San Lucas for the first time.

I average over 50 MPH just fine in my work trucks (a Ranger and F150).  Most of the regular traffic seems to be handle to handle those speeds fine.  Sometimes freight vehicles have trouble climbing east from CA 25 on the Mustang Grade.  The sight lines are pretty generous and it isn't too hard to pass them.

[kphoger]

Google Maps doesn't just use speed limits, which means it must also use real-time data from real people.

When I plotted driving directions just now along CA-198 between Alcalde Road (Coalinga) and the CA-25 junction, it told me it would take 42 minutes, which comes to 47 mph.  But if I set a different departure time, then it tells me "typically 40 min", which comes to 49.35 mph.  Now, I'm not familiar with the area, but, for a mountainous road with a speed limit of 55 mph, that seems very reasonable as a realistic average speed for many drivers.


When I'm planning a trip, I typically round up or round down from what Google tells me, depending on the terrain.  I'll round up for urban driving and mountain roads, but I'll round down for drives on the open road.

[Rothman]

Meh.  I've also found Google Maps to be optimistic for curvy or mountainous roads.

Had a blast driving up CA 49 for the Sacramento meet in our speedy convoy, but there was no catching up with Google.

[vdeane]

Oh yeah, that reminds me, I've been meaning to find out whether this is still drivable. It's now signed as a dead-end from both ends and Google also shows a gap, but I'm not sure what happened or why.

*checks the inventory*

Looks like the railroad crossing was removed in 2022.

[CoreySamson]

Earlier this year I got a little lost in Anna, TX after Google said that going straight here was permitted. For context I was getting out of the QuikTrip just to the south and was trying to go NB on US 75 without sitting through that Buddha-awful FM 455 interchange again.

[Max Rockatansky]

Google Maps doesn't just use speed limits, which means it must also use real-time data from real people.

When I plotted driving directions just now along CA-198 between Alcalde Road (Coalinga) and the CA-25 junction, it told me it would take 42 minutes, which comes to 47 mph.  But if I set a different departure time, then it tells me "typically 40 min", which comes to 49.35 mph.  Now, I'm not familiar with the area, but, for a mountainous road with a speed limit of 55 mph, that seems very reasonable as a realistic average speed for many drivers.


When I'm planning a trip, I typically round up or round down from what Google tells me, depending on the terrain.  I'll round up for urban driving and mountain roads, but I'll round down for drives on the open road.

Maybe the software has been improving on giving an accurate time estimate?  I haven't used the service to plot that route in a couple years.

Worth noting, I've noticed a considerable untick (relatively speaking) on CA 198.  When I first moved here in 2016 it was pretty typical to only see 5-10 cars headed the other way between Coalinga and San Lucas.  I usually see about 20-30 nowadays when I make the crossing.  It makes me wonder sometimes if posting about the highway so much on my page had a small-scale local effect in drawing people away from 152 and 46?

Had a blast driving up CA 49 for the Sacramento meet in our speedy convoy, but there was no catching up with Google.

One of the best kept secrets in California is the lack of hand holding on mountain roads when it comes to speed.  It is up to you as the driver to figure out how fast the road can be driven.  It certainly is a huge contrast to Arizona where ADOT signs nanny speed limits on mountain roads.

[kphoger]

Maybe the software has been improving on giving an accurate time estimate?  I haven't used the service to plot that route in a couple years.

Back then, were you plotting only the mountainous section?  That is to say, are you even sure that's what was making the difference?  I think Google's estimates are less realistic the more stoplights you add into the mix.

[Max Rockatansky]

Maybe the software has been improving on giving an accurate time estimate?  I haven't used the service to plot that route in a couple years.

Back then, were you plotting only the mountainous section?  That is to say, are you even sure that's what was making the difference?  I think Google's estimates are less realistic the more stoplights you add into the mix.

No, I was plotting from NAS Lemoore to NPS Monterey.  I would drag the route down from 152 to 198 to see what estimates I would get.  I was already familiar with 198 from trips to Pinnacles National Park and estimates I was getting for 198 didn't make sense.

[kphoger]

I was plotting from NAS Lemoore to NPS Monterey.  I would drag the route down from 152 to 198 to see what estimates I would get.

Yeah, that's backward from what I'd expect of Google.  The only thing I can think of is that Google's preferred route via 198 bypasses Salinas to the south;  going through town and sticking to state highways instead adds nearly 15 minutes to its estimate.

[Max Rockatansky]

I was plotting from NAS Lemoore to NPS Monterey.  I would drag the route down from 152 to 198 to see what estimates I would get.

Yeah, that's backward from what I'd expect of Google.  The only thing I can think of is that Google's preferred route via 198 bypasses Salinas to the south;  going through town and sticking to state highways instead adds nearly 15 minutes to its estimate.

There are several ways to make that transition from US 101 and CA 68 more efficient by avoiding Salinas.  The best I've found is departing 101 at Chualar.  From there it is an easy transition to CA 68 via Chualar River Road and River Road (County Route G17).

[webny99]

Oh yeah, that reminds me, I've been meaning to find out whether this is still drivable. It's now signed as a dead-end from both ends and Google also shows a gap, but I'm not sure what happened or why.

*checks the inventory*

Looks like the railroad crossing was removed in 2022.

Yep, looks like this was ordered by CSX and NYSDOT due to accident history at this location: http://macedontown.net/incoming/misc/2022-10-19_4984.pdf

It was useful as a through road - particularly as a northern bypass of Macedon village - but the crossing was at a very strange angle and likely too costly to correct.

[vdeane]

Oh yeah, that reminds me, I've been meaning to find out whether this is still drivable. It's now signed as a dead-end from both ends and Google also shows a gap, but I'm not sure what happened or why.

*checks the inventory*

Looks like the railroad crossing was removed in 2022.

Yep, looks like this was ordered by CSX and NYSDOT due to accident history at this location: http://macedontown.net/incoming/misc/2022-10-19_4984.pdf

It was useful as a through road - particularly as a northern bypass of Macedon village - but the crossing was at a very strange angle and likely too costly to correct.

The crossing also appears as if it may have been profile deficient.