How Does Google Maps/Directions Work?!
Discussion
Started a journey about an hour ago - it was supposed to be 1hr 45 mins with no issues. Realised something was up as the duration never went down the nearer I was getting to my destination.
Anyway big load of sh*t happening M25/Dartford crossing.
So Google says 1hr 53 mins for the trip but in red says +1hr 56 mins where the congestion is. So is it now saying it's basically going to be 4hrs ? The reason I ask is that from where I am the trip would never be 1hr 53mins so it must already be including some of the congestion time ?
Anyway big load of sh*t happening M25/Dartford crossing.
So Google says 1hr 53 mins for the trip but in red says +1hr 56 mins where the congestion is. So is it now saying it's basically going to be 4hrs ? The reason I ask is that from where I am the trip would never be 1hr 53mins so it must already be including some of the congestion time ?
sherman said:
Why would you not use the other suggested route?
Do you really want to sit in a massive traffic jam?
ULEZ/CAZ/Congestion charge nonsense?Do you really want to sit in a massive traffic jam?
OP, Google Maps uses data from other people using Google Maps/Location services to estimate the time based on the number of people's phones reporting in.
t" was about to happen?dibbers006 said:
I think it does this when the traffic is at a standstill for prolonged periods.
It can't give you an ETA so it kind of breaks.
this ^^It can't give you an ETA so it kind of breaks.
Google maps takes the speed of vehicles from users phones in that vehicle. Effectively anyone running google is a speed sensor for the system. The system can then average those speeds out and calculate a time to cover a certain distance. The problem comes when speed gets down towards zero. Here because speed is a reciprocal ie Distance divided by Time, the time climbs exponentially towards infinity.
ie to travel 1 mile at 1 mph takes 1 hour
to travel 1 mile at 0.5 mph takes 2 hours
at 0.25 mph, 4 hours
at 0.1 mph, 10 hours
each reducing in speed by 50% doubles the journey time
So when cars and the phone users in them are stationary or close to stationary, the statistics become unreliable!
The 1 hour 53 is a guess by Google, which includes some kind of statistical estimate of how quickly delays in that area clear after an accident (and can be surprisingly accurate)
The 1 hour 56 delay is an indication that someone on that part of the journey where the crash is has been delayed by 1 hour 56 minutes (and will keep going up if traffic is stationary as they are getting delayed more).
If you set off now, you may or may not be delayed by nearly 2 hours at the crash site, depending on how quickly the accident clears.
Personally with that info, I'd take the M11, round the North Circular A406 past Barking, across the Woolwich Ferry, and back out on the A20 as that's usually quicker than slogging all the way in and out to use the Blackwall Tunnel. Google doesn't recommend that route as it involves a ferry, despite the ferry being free. Alternatively, just go around the M25 the other way past Heathrow - it doesn't take much of a delay for two thirds of the M25 to become quicker than one third, though does cost quite a bit more in petrol.
The 1 hour 56 delay is an indication that someone on that part of the journey where the crash is has been delayed by 1 hour 56 minutes (and will keep going up if traffic is stationary as they are getting delayed more).
If you set off now, you may or may not be delayed by nearly 2 hours at the crash site, depending on how quickly the accident clears.
Personally with that info, I'd take the M11, round the North Circular A406 past Barking, across the Woolwich Ferry, and back out on the A20 as that's usually quicker than slogging all the way in and out to use the Blackwall Tunnel. Google doesn't recommend that route as it involves a ferry, despite the ferry being free. Alternatively, just go around the M25 the other way past Heathrow - it doesn't take much of a delay for two thirds of the M25 to become quicker than one third, though does cost quite a bit more in petrol.
sherman said:
SimonTheSailor said:
sherman said:
Why would you not use the other suggested route?
Do you really want to sit in a massive traffic jam?
Who says I didn't ?Do you really want to sit in a massive traffic jam?
I was sitting in the services wondering how stuff worked. The answers might prove useful in the future, might prove useful to other people who find the thread.
I followed the suggested route through London avoiding the M25.
I was driving back to Switzerland from Italy last weekend. Per Google the trip should have taken just over 7 hours. It actually took 11 hours, and only because I had a Telepass transcoder thingie for the toll stations, without which it would haven taken 12+ hours.
That's a pretty pathetic estimate. Is Tom Tom more accurate than this?
That's a pretty pathetic estimate. Is Tom Tom more accurate than this?
Fink-Nottle said:
I was driving back to Switzerland from Italy last weekend. Per Google the trip should have taken just over 7 hours. It actually took 11 hours, and only because I had a Telepass transcoder thingie for the toll stations, without which it would haven taken 12+ hours.
That's a pretty pathetic estimate. Is Tom Tom more accurate than this?
That's strange, as I've always found Google estimates to be fairly accurate. Last year I drove across France, into Germany and Switzerland, and Google maps was never more than a few minutes out.That's a pretty pathetic estimate. Is Tom Tom more accurate than this?
Tom Tom was also ok when I used to use it, but stopped years ago as I didn't want to pay for maps/updates.
Fink-Nottle said:
I was driving back to Switzerland from Italy last weekend. Per Google the trip should have taken just over 7 hours. It actually took 11 hours, and only because I had a Telepass transcoder thingie for the toll stations, without which it would haven taken 12+ hours.
That's a pretty pathetic estimate. Is Tom Tom more accurate than this?
TBF if the average speed / speed limit is say 70 and you pootle along at 50 it's hardly google's fault That's a pretty pathetic estimate. Is Tom Tom more accurate than this?
I'm disappointed if I can't knock at least 10% off Google's estimates
(First sentence somewhat tongue in cheek, unless there are delays, the estimates are usually pretty good although I prefer Waze)
QJumper said:
KTMsm said:
(First sentence somewhat tongue in cheek, unless there are delays, the estimates are usually pretty good although I prefer Waze)
I prefer Waze too, but find it's terrible for draining my battery. Is there a setting I can change, or is that usual?UGREEN PD/QC 30W Car Charger
and a phone that accepts at least an 18W charge and you'll leave the car with a topped up phone even if it was empty at the start...
cedrichn said:
I feel like Waze makes you take every small street full of speed bumps, just to avoid a red light on a main street where 2 cars are "queuing".
I feel like Google Maps tends to do it less.
But even google maps will make you do the strangest of things.....head down the tiniest little country lanes or even tracks just to avoid a little bit of traffic queuing for temporary lights on the main road. Its often a non sense that needs over ruling.I feel like Google Maps tends to do it less.
Edited by MattyD803 on Thursday 23 June 08:38
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