UKC

Hi All,

Long drive across France coming up.  Just thinking logistics.  Does anyone know if google maps uses the poor weather 110kph or the good weather 130kph when calculating times?  I'm trying to work out if its really going to take us THAT long.

Thanks

It doesn't use either. It uses data collected from users to give a real world time. You can test this out by asking it to estimate time from location A to location B, 60 miles along a 60mph single track road in Northern Scotland. It definitely doesn't tell you 1 hour!

Edit: Also the time estimate and even the route constantly changes depending on the current road works, traffic conditions, etc. etc. It is an estimate for right _now_, not tomorrow or next year or during rush hour or whatever.

Cheers.  That makes sense.  So I'll probably be a bit quicker if its dry and a bit slower if its wet but it should be reasonably accurate.

You can also set a departure time and day of the week and it will calculate per typical traffic on that day. Quite helpful if driving at night – or conversely on a Friday afternoon

I drive to the far end of Italy fairly often.  I tend to stick to 130kph, or the prevailing limit, as being 'creative' with the speed limit is just too much grief overall.  The exception will be getting away from a vehicle that is worrying or a PITA, so that normal service can resume.  Planning speed is 60mph/100kph for entirely motorway-based driving.  Leaving the motorway at beginning or end for any distance drops that to 55mph/90 fairly quickly.   Any breaks are on top of that.  500 miles/800km is OK.  600/950 seems to make for a long day. 

The traffic will be determined on the day - two hours sitting in crawling traffic will make your long day into a very long day.  We just try and avoid being near big cities at busy times, and avoid prime holiday travel times.   

Note that if you see a speed trap warning sign on a French motorway, there will be a camera somewhere in the next 5km.  

I’ve got google powered sat nav in car and it is live updating. Changes in response to whatever traffic conditions is on route including suggesting alternative route with time difference. Google now uses user input data to be updated as quickly as possible. User input can be automatic (eg detects car say slower than expected time for that road, being stopped for a period of time etc. (connection by eSIM which is always on) or user manually inputing details like lane closure, congestion, accident, etc.

I’ve been caught out checking traffic details and timing whilst at home, planning accordingly, and when getting in car discovering it was going to take 40% longer than I anticipated 🫣! Works both ways though. Seen the time to destination going down as whatever was slowing traffic has changed.

A warning in case you were tempted: do not rely on Google Maps/ Waze to tell you what the speed limit is if you can't remember whether the last sign you passed was 130/110/90 etc.

Google's accuracy on speed limits in France is awful. Less than 50% chance of it telling you the correct speed limit on the motorways of Northern France. And that's without worrying about complications like the weather or current traffic conditions. 

With reasonable quiet french motorways, we consistently beat Google's journey times despite driving at less than the speed limit.

The algorithm is really smart, I did a trip last year towing a trailer which was roughly 50% German motorway (so max 100km/hr with slow traffic) and 50% B roads and within half an hour it had calculated within the minute my actual arrival time. A couple of weeks later using the same nav on my 900 Yamaha running roughly double the speed all the time it again got it dead right, it appears to quite happily accept I will be running "considerably" over the speed limit for the entire distance and traffic jams will not be a major problem.

I have also found google maps timings to be surprisingly accurate.

However , not so clever in route choice off motorways. Always seems to pick the shortest route without any common sense or logic. I try to check against a real map before committing to a route chosen by GM, especially driving across rural France or Spain. Sends you through the congested village centres rather than the by pass to save 50m.

I noticed that last summer too. My phone often suggested a different speed limit to what I actually thought it was.

I won't be going over 130kph on the motorway as I'll be in the Berlingo and it already feels like warp 9 without going any faster!

Don't forget you can specify when you're starting your journey with googlemaps, that also has an effect on times.  The live traffic congestion warnings/heat map are pretty good too.

As Jim says, Google Maps updates on the go depending on upcoming traffic. If somewhere ahead on your journey has poor weather, Google knows because drivers in that area will have slowed-down from their usual 130kph+. 

I use it for driving the length of France and it's generally accurate, especially as the toll roads are much quieter than UK motorways and therefore much more predictable. 

It has, however, sent me on some very rural routes before I get to the motorway, or sometimes to avoid bad traffic around Paris.

FWIW Waze is much much better for driving than Google maps, the community avidly logs all manner of road side incidents, traffic etc 

I find those kind of notifications a bit of a mixed blessing. Occasionally they're really useful, but more often they're just a bit of a distraction. In any case, Google is starting to port the concept across to Google Maps now anyway. I suspect a lot of the data the two systems use is shared between them anyway, but I don't know for sure.

The data has been shared between the two for many years. 

Bizarrely, this does not mean that the two platforms agree on traffic conditions, routes, journey times, or even which roads are open.

The huge benefit of Waze is that it allows you to avoid certain road types, so you don't find yourself being directed into a clean air zone that your vehicle isn't permitted to enter. 

I also found it really helpful in France as Waze not only told me if the route was on a Peage, but also what the roll would be. Tolls in Normandy looked seriously expensive, whilst elsewhere they were not enough to be worth rerouting to avoid. Google just told me there was a charger, with no indication of how much.

Good to know. Thanks. I don't think I need that info in the UK very much, but last time I drove to Font it was really difficult to tell whether or not Google Maps was trying to take us through the Paris clean air zone.

You have to set it up first as to which zones you want to avoid, and if I'm linked to the car annoyingly it doesn't show on the display. So I set Waze running handheld on my phone, again it will offer the zones but with a warning so you can choose an alternative, then plug into the car once I've chosen the route. 

This feature is why I now prefer Waze.

Wish though that imperial used yards rather than feet for advance warnings about junctions, that freaked me out! I've had to resort to metric and just suffer the distances being in km rather than miles.

Yes - did this on Wednesday for a journey leaving at 7am and gave an arrival time range of 1h05-1h35. Meant I needed to leave at 6:30 instead!

I'd agree with this. Just back from South of France, having had a hire car with a Google-powered sat-nav. On motorways, it seemed to register the last sign passed, regardless of whether that was for the main carriageways or junction slip-roads! Couple of the A-roads seemed to have a lot of variation in speed limits - again, I suspect it was picking up a sign that was actually for a side road.

Mind you, our Volvo at home seems to have the same erratic behaviour - it's claimed a 70mph limit for a road I know for a fact is 30mph!

Yes, it's kinda inconvenient for the usual "sorry, I got stuck in the traffic, you wouldn't believe how bad it was!" excuse