GPS (Garmin) accuracy

10 watchers

Nelly Jul 2016 10:45am, 8 Jul 2016 3,377 posts	0 Nelly Old Croc - if you are reading, I wondered if you could answer a question for me please? My question relates to interim distances within the race route (e.g. mile/km markers, half way, etc). Presumably the location of these points is included within the course measurement report? If so, I also presume the same "Short Course Prevention Factor" (of 0.1%) as the full race distance is applied to these measurements. I suppose, what I'm really asking is, where is the extra 42m of a marathon, for example, added to the total distance? If it was added after the 26mile marker, for example, it could make a massive difference to those tracking pace against mile markers! Thanks.
CharlieP Jul 2016 10:51am, 8 Jul 2016 193 posts	0 CharlieP I always assumed the mile/km markers were only as accurate as the position of the nearest handy lamppost or tree!
The_Saint Jul 2016 1:01pm, 8 Jul 2016 5,849 posts	0 The_Saint Not if they are sprayed on the tarmac
paul the builder Jul 2016 1:13pm, 8 Jul 2016 5,678 posts	0 paul the builder I'd be interested in Old Croc's answer. I always assumed it is not the responsisbility of the course measurer to actually mark the route out (Start/Finish, or intermediate points). And that it was the race organiser who slapped down the mile markers etc. And they doubtless (at best) travel the course with a GPS and mark paint/lamppost, so those markers can't be expected to be accurate, sadly.
K5 Gus Jul 2016 1:38pm, 8 Jul 2016 1,892 posts	0 K5 Gus I thought the same as PtB, ie course measurer only responsible for getting the finish line at correct point relative to start line, and all intermediate markers not their responsibility.
Nelly Jul 2016 1:40pm, 8 Jul 2016 3,380 posts	0 Nelly I always assumed the same Paul/Gus. However, when reading the course measurement report for the London Olympics course I noted it said "we stopped and noted references at all locations required for split points" and gives exact locations of every mile/5k location. Now obviously the Olympic marathon is a special case, but I wondered if providing such accurate location info was an exception for the Olympics (understandably) or if this is the norm. And if it is the norm to provide accurate split locations (maybe not every mile for "normal" races, but e.g. just halfway), if the SCPF is included in that measurement or only at the end.
CharlieP Jul 2016 1:50pm, 8 Jul 2016 197 posts	0 CharlieP It won't just be the Olympics - the London Marathon has split times (at 5 km intervals and half way), as will the IAAF Worlds, Europeans and other major marathons. results-2016.virginmoneylondonmarathon.com Given that the IAAF recognise split times as world records (the 20 km world record was set during the Lisbon Half Marathon and the 30 km world record during the Berlin Marathon), these obviously need to be as accurately measured as possible. I don't know about the SCPF though - it's an interesting question!
The_Saint Jul 2016 4:42pm, 8 Jul 2016 5,850 posts	0 The_Saint Our club's certified course measurer listed on here coursemeasurement.org.uk does the mile/km markers and writes a detailed positional log for each one against permanent features such as houses and numbered street or railway objects - I know because I had to find every one to re-mark for our 20 miler
Nelly Mar 2017 11:01am, 31 Mar 2017 3,719 posts	0 Nelly So in the first few months of this year it's been announced that the courses at two more high profile races have been found to be short (http://www.bbc.co.uk/news/uk-scotland-38798775 & today @ http://www.brightonhalfmarathon.com/bhm-2017/statement-100317/). On both occasions I believe it was the fault of the organisers setting out the course different to the certified course. And I'm also aware of an autumn marathon last year in which the competitors almost certainly didn't run the measured route. To my knowledge, UKA have never commented on any of these issues. Isn't it about time that they publicly reminded race organisers of their responsibilities? After all, paying for course certification is pointless if you are not going to set the course out as measured.
larkim Mar 2017 11:19am, 31 Mar 2017 1,784 posts	0 larkim It does seem to be an area where perhaps very high standards have slipped slightly in the last few years to create some of these issues. Though perhaps its as much the proliferation of GPS data which is highlighting it more than it might have done a few years ago. Not sure why UKA would need to publicly remind race organisers of their responsibilities though - I'm sure they are only too aware of the issue and the post-race embarrassment of getting it wrong.