I think we're overcomplicating the question here.

Let me put it in more simple terms; aside from the pros/cons of various ways of planning a route, if I search for driving directions for London to Cape Town in Google Maps (simply for the purpose to get an idea of the rough distance involved) will the distance it gives for a journey that long, be accurate?

Thanks

Ed

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Where Next Barney? / Trans Morocco Trail

I like this topic. I think I know what you are looking for but it is funny to read you want a ¨accurate¨ distance for a ¨rough idea¨
Don´t get me wrong, I am merely joking here

You an Sushi seem to take the whole distance from google maps and multiply that with some number. The outcome must be a very rough idea I think. I don´t do that. I like to take shorter sections and drag the route, given by google maps, to the roads I plan to drive. Then the outcome is fairly accurate.
For me, that way of planning is part of the fun, I like playing with it and maybe I have nothing better to do with my life

In a perfect world the outcome would be 100% accurate, but what is accurate?
I drive a 4x4 but there is quite a difference in distance what my car shows and what my gps via Orux maps shows. Part of the problem are probably the bigger tires under my car.

I think the asnwer to you question is NO. It won´t be accurate.
Not taking into account whether there are any mapping issues, there is something else what bothers me.

Google maps shows the distance for parts of the route we are traveling by ferry.

For example: it shows London - Cape Town to be 8185 miles via France. But its shows 8144 miles when taking the ferry from Plymouth to Santander. This is only a small difference although the driving distance that Mark(harf) is talking about is considerably shorter.

Lol, thanks Rognv.

Yes, you're sort of right - before I start to plan, I typically have a rough idea of budget/time I can spend away before a trip and know that I'll typically average around 150km-175km a day. So I use Google Maps to get a rough idea of what kind of trip might be possible in that time.

Once I've decided on where I'm going, I'll establish a rough direction of travel and then work from area to area when I'm in-country, typically planning the detail of where I actually go for two - three days ahead, using (until recently) Outdooractive and (now) Osmand and Open Street Maps.

So, I don't actually use Google Maps to plan a route - just to understand what in theory might/might not be possible given my constraints for that particular trip. Hope that makes sense.

I see what you are saying about the distance from your wheels, by the way - the reason why I asked this question was that when riding London to Sydney, my bike odometer clocked 60,000km by the end of the trip, which seemed a lot higher distance than when later on tried to copy my trip onto Google Maps.

Cheers,

Ed

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Where Next Barney? / Trans Morocco Trail

I think you are over-complicating things here... as an overview over a long distance (which has limited real-world practicality anyway), then Google maps going to give you an approximate distance value as a straight line...

However as soon as you 'calacutate' directions, it's going to snap to the [what it considers] is the most efficient next work of roads (and any ferry routes etc) which have been far more accurately catalogued with regard to actual distance over the ground.

The world is a BIG place - you can't expect to navigate around it all in one hit. Practically speaking you're going to break it down into country, weekly, daily portions anyway... just keep a tally of how far you've actually travelled (from your odometer or GPS track-log) if that sort of thing really matters to you?

Jx

Potentially yes re: over-complicating things a little.

But as per my earlier post, I'm not actually looking to use GoogleMaps to plan in detail and take a very different approach to this (as set out), or even keep to keep a tally of the distance. It was more a general question/point!

Cheers,

Ed

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Where Next Barney? / Trans Morocco Trail

AFAIK Google Maps plans a road route between points A and B, so curvature is irrelevant. You will not be travelling "as the crow flies". Rough estimates of distance are all very well for planning, but they will necessarily be approximate, nothing more.

But to the OP, if you zoom right out and then move from one location to another, you can see the shapes of the land masses change, so yes, Google does account for curvature.