G-maps accuracy -- settling the debate

the smartest letsrunner wrote:

I have seen something like 63 threads in the past year asking if Google Maps / Gmaps pedometer is accurate enough to measure training routes, tracks etc.

Every single time, someone posts that they measured their local high school track and got 399.7 or 400.2 meters and therefore it is not accurate.

Some luddite will generally jump in saying that these "gizmos" are not useful for serious runners.

Here is an idea: Find an outdoor pool in your area, as in an Olympic-sized (50m) pool. Preferably one that a serious club team uses for competition. Any such pool will be precisely 50m - they have to be laser-sighted to be certified. Zoom in and measure it, corner to corner, not on a diagonal. Note the result.

Gmaps for the win!

What about on a not so flat surface?

That's tricky. You'll need to find an uphill pool.

I ran this one in the weekend - select Hybrid view and take a closer look.

http://www.walkjogrun.net/routes/current_route.cfm?rid=6564B733-0455-1C1A-05134B090FB94043

No, the race doesn't start on the beach, it starts on the road and at no point was I running in the water either.

Plenty of google maps errors online if you search for them. Most likely o.k. if you realise there are limitations and are just using them to plan a route for an easy run, but I certainly wouldn't want to tell a race director than his course was short or long based on what google maps said.

Fair enough. And you're smart enough to live in New Zealand, the most beautiful place on earth, so I won't argue.

I definitely wouldn't suggest measuring or debating course measurement with these programs - that's for the officials. I'd be pretty comfortable measuring training routes, even for long repeats etc, as long as you map it out manually, not just using the 'automatic for runners' functions...

I didn't know there was any debate anymore. Just uninformed people.

Over short distances with straight lines, it can be extremely accurate. Over more complex routes with lazy lines (or 'follow roads' feature) it'll get less accurate, and usually long. Over more complex routes with painstakingly drawn lines, it's fairly accurate, usually within a hundredth of a mile or so, but not 100% trustworthy.

Bottom line, these tools are good for measuring workouts, long runs, etc., if you take the time to do it well. They're not good enough to know down to the meter or to certify race courses with.