How important is an accurately measured race?

lecheile

There have been a number of races in the last couple of weeks where there has been issues with course measurement. Last year was characterised by commercial/charity races with a haphazard approach to certified course distances but in the last few weeks we have had examples of AAI permitted races where there has been a question over the course measurement.

Examples include:

(1) A regular race in the BHAA calendar is run 400m short
(2) A 'commercial' race was issued with an AAI permit where the course was measured by the race organiser (although the distance was not questioned)
(3) The largest 5 mile race in the country was confirmed by the organisers as being short

Personally, I assume that when I run an AAI permitted race that I can rely on the distance being one that is properly measured and certified by a competent course measurer (a pre-requisite for issuing an AAI permit) but current form indicates that such an assumption may be unjustified.

So in an effort to inform those who organise races as to the importance (or otherwise) of presenting an accurately measured course - how important is a correct distance to you?

xebec

For me it depends on the race, to go with two examples you mentioned:

(1) BHAA race: For me these races are more about competing against other runners of a similar standard that I see at most of the races. The time is nice, but I get more satisfaction from beating someone who usually beats me. I'm not what others would call competitive in these competitions - I'm happy if 20% of the field are behind me - but I do like to have the personal battles.
(3) 5-mile: For me this is more about my own personal challenge. While I might spot others that I race in the BHAA, it's unlikely due to the numbers. Organisers of mass participation races like this have no excuse in getting the distance wrong. They are raking in over €100k for a race like this, surely a small investment is required for accurate measurement. Despite the crowds and the tough course, I was on for a big PB yesteray, I feel denied this because of the error.

That said, the Race Series organisers at least have a chance to rectify the situation with their two remaining races.

Hope I made my point clear about the difference between the two races for me.

gerard65

A race should do what it says on the tin. If it claims to have an accurately measured course, well it should be. There is no excuse for distances on roads to be out by over 100mtrs. If the race does not state its accurately measured its fine if its out. You should get what you pay for. Not sure if the BHAA race was advertised as bang on 5k and I think there was some confusion as to a lap of the track anyway, but their road races are usually measured by a jones yoke. But the adidas series has started patting itself on the back over the last couple of years and the success and easy money (big numbers competing) may be making it complacent. Claims like 'we're the biggest 5 mile road race in the world' is amusing. We're the paying customer and we're only asking not to be treated like mugs.

RayCun

I wouldn't run a race if I knew it was going to be short. I might run a race that was bad value, or on a tough course, or I knew would be crowded, or would start late, or.... but not one that was the wrong distance.

But anyway, it's done now.

aero2k

Depends on the race.

If it's mainly a charity one, with a small field, then I'd be mildly annoyed if it was short, but wouldn't complain.

If it was something I'd trained specifically for over a long period, and was so arduous that I couldn't do another one within a few weeks (e.g. a marathon), then hell would have no fury like aero2k.

Yesterday's 5m race falls somewhere between those 2 extremes, though the importance of getting the distance right is in direct proportion to reasonable expectations, and in this case over €100k entry fees + the organisers' website claims adds up to a lot of expectation.

RoyNeary

Very important. Let's hope that it doesn't become 'all about the goody bag and free stuff'.

robinph

The likes of BHAA are generally very good at their road distances, but I'd not be overly annoyed with a slightly off distance course as it's also about the brack and chatting and team prizes afterwards. They are usually very good with their road distance races.

The likes of a charity event I'd like to have a decently measured course, might not expect it to be totally spot on but if it's not even close then they wouldn't be getting my money again the next year.

Club run races I'd expect to be spot on as a point of principle on their part, but if they say it's an approximate distance then that is fine. Good cakes afterwards helps.

Purely commercial ones must be 100% with the distance, and I'd put the likes of the race series ones leading up to the DCM and the Great Ireland ones as having a responsibility to show everyone else how it's done as they are at the top of the pile. Between them they have multiple major corporate sponsorships/ TV coverage/ international runners coming over to race and the biggest single participation events in the country. They have to be better than perfect. Crowds are an issue, but that is just good preparation for the likes of running in a major marathon which are always busy, the distance has to be spot on though for their courses though.

RoyMcC

Really there's no excuse for a 'short' race. Using a properly calibrated Jones counter (officially recognised) or a GPS, measure on the shortest possible route, check by remeasuring back from finish to start, add say 50m and you have a course that is 'not less than' the stated distance.

Easy, just needs a little time and care. The only thing that can go wrong from there is that an incorrect course is run.

racheljev

To me, it's very important. I'm not a member of a club, I don't enter a lot of races and I'm a mediocre runner at best. It's just me and my Garmin out there every morning! But I'm a mediocre runner who gets a little bit faster every now and again. Last year was the first time I ran this Irish Runner 5 mile and I was looking forward to this year so I could see if I was getting better. I was very disappointed when I realised the course was short. I did the Aware 9/10k in December and I wasn't happy about the short course - but, money was for charity, etc etc, so I didn't get too aerated about it. However, Saturday was a different kettle of fish - expensive enough entry fee, official DCM link up - it should have been perfect. No amount of goodybags, tshirts and sweets (I got midget gems, I would have killed for jelly babies ) can fix that. And I saw the post in another thread which said, run 5m around the park and you'll have your pb, what's all the complaining about? I know I can't replicate a race atmosphere on my own at 6.30a.m - that's what I paid my 20euro for, I should have a nice shiny pb to shout about. Anyway, at the end of that long rant, to me it's a nobrainer. If a race is advertised as a certain distance, at the very least it should be that distance, end of.

tunney

Happens in some triathlons as well. Thinking that if they are short then people get PBs and everyone wants to do them.

Doesn't quite work Doesn't stop people doing it though.

meathcountysec

The essence of the sport, whether it be on track or road is accurate measurement of time and distance. You are competing against yourself over a known distance/time. Of course the distance should be accurate, as should the time. Otherwise what's the point?

TheRoadRunner

I think it's very important, the most vital part of any well run race.

The one exception I would make is when it comes to cross country. Generally I run a lot slower over the muck and ****e so if the course is a little longer or shorter it generally doesn't bother me as I treat it as a race against other runners purely and times or personal records never come into the equation.

nerraw1111

It's important to my wallet. I pay for the distance, I expect to get what I paid for. Really that simple for me.

To quote Fr Liam Deliverance from Fr Ted: "It's shoddy, shoddy workmanship."

However, personally, I'm not at a stage or a mindset where a PB is that important to me.

If it is less than 150 metres short, I wouldn't be too pushed as it'd be relatively easy to recalculate the time. But totally understand why it matters to some.

bazman

An accurate course is critical for any road race. The idea of a PB in Ireland on the roads is now a joke. Championship races & well established routes seem to be the only trustworthy races ...

Organisers of these races should ensure the distance is as advertisied and AAI should ensure that if they saction a race that it is accurately measured.

DustyBin

The distance for any road race should be accurate full stop.
What's the point in having a 5 mile / 10 mile / 5k / whatever distance race if it's not right?
I've no bother running a race not measured by a jones counter or certified by an official whatsit so long as the organisers have bothered their a@&£ to go out and measure it some other way, or even just ask a local runner to go check it out with a gps watch.
Not being the advertised distance is inexcusable no matter what the profile of the race. If people can be bothered to turn up then the organiser could surely bother to make an effort to measure it.

--amadeus--

IMO you pay for two things in a race, accurate distance and accurate timing. Anything else is a bonus. Get the time or distance wrong and you might as well not bother, they are the fundamentals of a race.

There is no excuse for an innacurate course. But there are reasons for it and the reasons can tell you a lot. From what I have read it sounds like the 5 mile course was accuratley measured but that the start line was incorrectly placed. That's human error and raises a lot of serious questions (if runners noticed it why did marshals not? If marshals did was a decision made to start on time with a short course rather than delay the start and move the start line?). That all said I know Hard_worker and I would imagine that he will be giving himself and the committee a hard time to get the answers to those questions and I can't think of anyone better to learn the lessons and make sure that it doesn't happen again.

And that kind of screw up is different - in my opinion - to a non-permited charity race being re-routed at the last minute by the authorities. And that is different again to a race group advertised as permitted when one of the distances was known well in advance to be signifigantly short but the organisers chose to keep this quiet and run the event anyway.

I suppose what I am saying is that it's always a crime to have a short course but not all criminals are equal!

There is also a lot more to this - have AAI standards slipped or do sites like this and the ready availability of GPS devices just mean that there is nowhere to hide for shoddy races? Either way standards have to rise and I think it's great that ART can bring this sort of thing out to wider public attention.

Which leads onto the next thing - running is a very small community and we all know each other. As ART has become more popular there have been closer links developing between race directors and organisers and teh site. Pacres are an obvious example but people like Eoin Ryan, Locteau and HW bring a huge amount of value to the site and a rapid way for questions to be answered and concerns addressed. But does that have an impact on how we judge thier races in comparison with a race with no ART connection?

aburke

bazman wrote: »

Championship races & well established routes seem to be the only trustworthy races ...

National Half Marathon 2005 (?), Tinryland, Carlow.
Short... well short. Rakes of 'PB's that day.
Many cross-country races are short too, but they are not "jones counter" measured.

shels4ever

aburke wrote: »

National Half Marathon 2005 (?), Tinryland, Carlow.
Short... well short. Rakes of 'PB's that day.
Many cross-country races are short too, but they are not "jones counter" measured.

Yep I don't mind an XC race been out a bit, Think the Dublin inters was long last year by about 700-800m nearly killed me but would rather a long course then a shorter on when it come to XC.

Road races should be spot on as there is no reason they cant be measured exact.

BeepBeep67

XC is usually due to logistics and I believe can be +/- 10% to accommodate multiple distances starting and finishing in the same area.
Personally I won't run a race that has a legacy of inaccurate distance, or until it's been accurate for few years at least.
I invest too much time, effort, money and run life balance to run a 4.9 mile race or whatever that will never be run at that distance again.

plodder

I don't recall any of the BHAA XCs being off by much recently. Sometimes, the exact position of the start line can be a moveable feast, but I'd guess the courses are walked with a trundle wheel to get them right. There's no excuse for big high profile road races though.

robinph

For an XC it doesn't really matter as the race is between the other people there and the conditions. You cannot compare one XC race time to another, or even to the same course the previous year. The distance for an XC race is mostly to give an idea of how hard I should be setting out at, although it's nice if they are close to claimed distance.

shels4ever

robinph wrote: »

For an XC it doesn't really matter as the race is between the other people there and the conditions. You cannot compare one XC race time to another, or even to the same course the previous year. The distance for an XC race is mostly to give an idea of how hard I should be setting out at, although it's nice if they are close to claimed distance.

True but all races are actually races.. but most people run them at time trials against their own times, would be nice to see how people woudl do if you had a 5 mile race and banned watches and no mile markers wher eyou jsut race the people around you. I've a feeling it would be pb's all round.....

robinph

One of the Raheny winter races banned watches I think and you had to guess your finishing time.

Warm Panda Cola

Saturday's 5mile race wasn't actually 5 miles?!!! Now i'm even more disappointed with my time:(
Surely it can't be that hard to measure out 5miles..??

BeepBeep67

plodder wrote: »

I don't recall any of the BHAA XCs being off by much recently. Sometimes, the exact position of the start line can be a moveable feast, but I'd guess the courses are walked with a trundle wheel to get them right. There's no excuse for big high profile road races though.

Agree, although easier to manage when you've only 2 races and 1 is double the distance of the other - try doing that for a full suite of races from U/9 to Seniors.

Condo131

--amadeus-- wrote: »

IMO you pay for two things in a race, accurate distance and accurate timing. Anything else is a bonus. Get the time or distance wrong and you might as well not bother, they are the fundamentals of a race.

I agree 100%. No further discussion!

--amadeus-- wrote: »

There is no excuse for an innacurate course. But there are reasons for it and the reasons can tell you a lot. From what I have read it sounds like the 5 mile course was accuratley measured but that the start line was incorrectly placed.

Unfortunately these things happen. I take a digital photo of each of my mile marks for all measured courses, which helps, but doesn't guarantee that marks will be placed in the correct location.

--amadeus-- wrote: »

I suppose what I am saying is that it's always a crime to have a short course but not all criminals are equal!

I get annoyed when I run a course that is short/long. When it's a major race, I get very annoyed and probably wouldn't go there again. When a championship course is out, I really start to bitch!

--amadeus-- wrote: »

There is also a lot more to this - have AAI standards slipped or do sites like this and the ready availability of GPS devices just mean that there is nowhere to hide for shoddy races? Either way standards have to rise and I think it's great that ART can bring this sort of thing out to wider public attention.

I have run in many AAI county and provincial road chps which have been disasterously short or long. Wrt to other races, I find, in practice, that many new races apply for their permit long before they may have selected their course, not to mention measured.

Imho, the AAI, as a whole, have been remiss in looking after this aspect of admin. There is no sanction available for events that are lacking in this respect, whether they are organised by the AAI, a club or any other body, except to withhold permits for future events. (But then we have several events now running without any permit! :eek:...but that's another can of worms :rolleyes: )

I agree it's past the time for incorrect courses to be highlighted. My own club's fixture list now lists the initials of course measurers, where known.

robinph wrote: »

For an XC it doesn't really matter as the race is between the other people there and the conditions. You cannot compare one XC race time to another, or even to the same course the previous year. The distance for an XC race is mostly to give an idea of how hard I should be setting out at, although it's nice if they are close to claimed distance.

XC and other off road courses can generally be adequately measured using surveyors wheels or GPS devices. I don't accept, as other posters have suggested, that distances can be 'adjusted' to cater for differing distances or that, for XC, distance isn't critical. Earlier this year, we had the National Master's Chp courses all short by approx. 25%. I once warmed up on a 4M XC course, finding that full course would have been approx. 7M :eek: - After protesting, a lap was dropped, but we still ran over 10k - for 4 miles! :eek:

We're probably spoiled in this part of the country. Very few courses have not been measured and everyone knows who has measured an established course and, whenever a new race pops up, the question is generally asked "who measured" it, or "did you measure it"

condo(r)131 - AAI National Grade Measurer.

Krusty_Clown

DustyBin wrote: »

or even just ask a local runner to go check it out with a gps watch.

You can't rely on a GPS watch to measure a course. They are quite simply not accurate enough. It has to be one of the formal methods (Jones counter) or at the very least, a trundle wheel.

Of course all the best intentions and best measured courses are for nothing, if someone doesn't actually use the measured distance for the race and locates the start/finish and mile markers in the wrong place. It's got to be one of those things that the race director himself/herself takes charge of, because it is so fundamental for the event (making sure it's done, rather than measuring the course itself). More important than making sure there is sufficient goody-bags at the end of the race.

TheRoadRunner

Condo wrote:

I don't accept, as other posters have suggested, that distances can be 'adjusted' to cater for differing distances or that, for XC, distance isn't critical. Earlier this year, we had the National Master's Chp courses all short by approx. 25%. I once warmed up on a 4M XC course, finding that full course would have been approx. 7M :eek: - After protesting, a lap was dropped, but we still ran over 10k - for 4 miles! :eek:

Agreed XC courses long or short by 25% is ridiculous. The masters wasn't the only course this year that wasn't anywhere near being accurate.

What I was initially trying to say is that if a XC course was short or long by 150 metres it wouldn't really bother me as much compared to a road race where I keep track of PBs.

DustyBin

Krusty_Clown wrote: »

You can't rely on a GPS watch to measure a course. They are quite simply not accurate enough. It has to be one of the formal methods (Jones counter) or at the very least, a trundle wheel.

Whilst I agree and understand that using a gps is not best practice when it comes to measuring a course I think you might be slightly missing the point I was attempting to make Krusty.
For me personally, in a lot of the local/smaller races that are on it doesn't have to be jones counter measured or have been certified by an AAI National Grade Measurer as such things are costly and time consuming.
If I'm entering a local race that's advertised as say 4 miles, costs me a tenner or so to enter, and it transpires that the course was measured using a gps and my gps broadly agrees on the day - then I'm happy out. In most of these instances the organiser has probably measured 3 or 4 times, maybe alternating between running and walking it or whatever - but they've made the effort and I'm happy enough with the accuracy of the course.
Now if there is another small local race that is advertised as 10k, costs me say a tenner to enter, and transpires to be approx 9.1k then I'm not very happy at all - that just laziness on behalf of the organisers that they couldn't go out earlier that morning and stick a turnaround cone somewhere on the course.

Now if I'm paying bigger money, and it's a higher profile race then I'd want it to be deadly accurate, measured on a jones counter pushed by condor himself!!

W.B. Yeats

I have simple requirements
1. Distance is right
2. Time is right and
3. Start time is punctual

1 and 2 are absolutes
3. has a degree of wriggle room

I wouldn't get away with paying 90% of the registration fee so don't expect to get an approximation for my requirements.

Question: is there a margin of error that is acceptable at all? (4.9/5 is 2% out)

Krusty_Clown

DustyBin wrote: »

If I'm entering a local race that's advertised as say 4 miles, costs me a tenner or so to enter, and it transpires that the course was measured using a gps and my gps broadly agrees on the day - then I'm happy out.

Fair enough and I'd probably agree with you on your set of standards. I'm just pointing out that watch-based GPS receivers offer accuracies of at best 95% (5% margin for error) and that's if and only if you follow a perfect race line. So racing the distance with your GPS based watch (with its own inaccuracies), it's quite likely that they distance will not broadly agree (and we're still talking best-case scenarios here). Of course having hundreds of runners running with GPS watches and averaging out the results may help (as we have seen).

RoyMcC

Krusty_Clown wrote: »

I'm just pointing out that watch-based GPS receivers offer accuracies of at best 95% (5% margin for error) and that's if and only if you follow a perfect race line. QUOTE]

You surprise me a bit there Krusty. My impression is that they are more accurate than that, or at least that's been my experience.

Example 1 - although I would normally Garmin a new training route only once, if I do it a second or third time the distances invariably match up to with a few metres.

Example 2 - Adamstown 8k and Dunshaughlin 10k I both found to be smack on the button as regards distance. Surely that would be a coincidence if your statement is correct.

Also, the grumbles about under or over-distances at some races usually bear some similarity as between the runners themselves.

Not necessarily disputing what you say though - is that '95% at best' a proven statistic?

Gringo78

W.B. Yeats wrote: »

Question: is there a margin of error that is acceptable at all? (4.9/5 is 2% out)

Condo feel free to correct, but I think an AAI Measured course will be measured to be 100.1% of the distance i.e a 5k course will be measured to be 5005m in length. This suggests a jones counter accuracy of 99.9%. So I think anything less is unacceptable. 2% on a 5mile race is 30sec error on the winning time..not on. 1% on a marathon and it'll be 400m short...again not on.

There are plenty of course measurers out there....for true charity races, many of these will give their time for free, for commercial races, theres no excuse not to pay one. A Jones Counter costs less than 100euro so even if they want to not go the certified route, no excuse not to be accurate.

Condo131

W.B. Yeats wrote: »

Question: is there a margin of error that is acceptable at all? (4.9/5 is 2% out)

SCPF (Short Course Protection Factor) in measurement is 0.1%. This is added, after calibration, to ensure that the course is not short. So...in 5 miles......the amount added is ...8.04 metres. 2% would amount to 150 metres = between 25 and 40 secs, depending on the athlete.

Btw, the vast majority run nowhere near the SPR (Shortest Possible Route). I'm constantly amazed that, in races, people take the long way round bends. On a twisty route, that can add a hell of a lot!

Burgman

Condo131 wrote: »

SCPF (Short Course Protection Factor) in measurement is 0.1%. This is added, after calibration, to ensure that the course is not short. So...in 5 miles......the amount added is ...8.04 metres. 2% would amount to 150 metres = between 25 and 40 secs, depending on the athlete.

Btw, the vast majority run nowhere near the SPR (Shortest Possible Route). I'm constantly amazed that, in races, people take the long way round bends. On a twisty route, that can add a hell of a lot!

This is why I believe that the "shortfall" announced by the race organisers of the 5 mile race last Saturday (149 metres) still does not resolve the issue. I am glad to see Krusty Clown (the resident expert on Garmins on this site I believe) expressing scepticism about the accuracy of GPS watches. I recorded 4.88 miles on Saturday. Add on 0.0926 mile and you still get only 4.9726 miles. I would expect that a Garmin watch should give 5.0x miles. I am certain that I did not run the most efficient line, even though I try to ensure that I do. Has anyone ever read the IAAF/AIMS document on race measurement? If you did, you would not have any confidence in the accuracy of a Garmin, usually worn by someone keeping to one sided of the road on a road with lots of bends. Certified course measurers have to go to great lengths to ensure an accurate course length.

shels4ever

Gringo78 wrote: »

There are plenty of course measurers out there....for true charity races, many of these will give their time for free, for commercial races, theres no excuse not to pay one. A Jones Counter costs less than 100euro so even if they want to not go the certified route, no excuse not to be accurate.

From what I've heard there isnt a huge amount of them to covery all the races that are now running.

Slogger Jogger

I measured the plod half marathon at 21k yesterday which is pretty damn good for a race which is offroad and over manys a hill. And it was a bargain. As the race director said in advance it was never going to be a PB-able route.

You pay a premium for most races these days. The least that you expect is that it is accurately measured and marked. Especially when some people will have trained specifically for them and may have nailed a PB - only to have it dismissed due to inaccuracy :mad:

robinph

W.B. Yeats wrote: »

Question: is there a margin of error that is acceptable at all? (4.9/5 is 2% out)

I think there is an acceptable margin of error for XC races, for road though anything less than the full claimed distance is unacceptable.

2% out for a marathon would be about 25 and a half miles, I don't think anyone would accept that. Missing any of the extra 385 yards would be too wrong.

lecheile

There are some very good points made about the other elements that are enjoyed and appreciated in taking part in races, but foremost in people's list of must-haves is a correct distance. I don't accept that race directors or organisers are prevented in terms of cost or access to the right resources, in getting a course properly measured and certified.

If you are arranging a race as a club or through a club, the local county board will have qualified course measurers available, many of whom provide the service at minimal cost. If you are arranging a commercial event, you need to plan for spending a few euro to have the course measured properly - and look for help early on! The course does not need to be re-certified unless some element of the course changes. Where a race carriers an AAI or other recognised label, this is on the basis of a course certificate being produced by a suitably qualified individual - this clearly is not happening in many cases.

MisterAdam

Burgman wrote: »

Add on 0.0926 mile and you still get only 4.9726 miles. I would expect that a Garmin watch should give 5.0x miles.

GPS was first launched in 1978. In terms of technology, it's a dinosaur - a dinosaur in polyester flares and platform shoes. It's favorite band is probably the Bee Gees.
Not only is it hopelessly out of date, but we're not even using its full potential. We only recieve the low resolution civilian signals. The US mlitary, who operate GPS, keep the really accurate measurements for themselves.
There are a few other, more technical, reasons why GPS is inaccurate. But I don't even almost understand them.
However, the biggest source of error has to be this - GPS calculates your position periodically and then assumes you ran in a straight line between each two points. If you don't run in a straight line, it'll underestimate the distance you ran. Anyone who has seen their estimated speed plummet when they round a sharp corner can testify to that.
The point is that the inaccuracy is skewed. Generally you'll have ran slightly further, instead of shorter, than your watch says. And it's entirely possible that, if you stick enough close to the corners, you can end up with a reading slightly shorter than the actual race length.

Krusty_Clown

RoyMcC wrote: »

You surprise me a bit there Krusty. My impression is that they are more accurate than that, or at least that's been my experience.

You're right RoyMcC. I went back and had a look through the 405 Garmin user manual (where I thought I'd seen the reference before) and didn't find it there. I actually found it in one of the older Garmin GPS devices I used to have (Garmin Quest).

Here's what it had to say (for that device):
GPS Accuracy Position: <15 meters (49 feet) = 95% typical accuracy
So the Forerunner is a little better than the 5% I previously quoted. Typically when I go running, the accuracy of my 405 would be around 25-45 feet, which based on Garmin's reckoning is probably around 3%-4%. Again, remember, this is the best case scenario. That's why the overall distance/pace is just a curiosity when I run a marathon. I still use a pace band and stop-watch. Garmin's are a valuable aid for training and racing, but they're just an aid.

Now, let's go back to the 1,000 mile challenge, and knock 3-4% off of all the Garmin users.

robinph

Each individual point recorded may be off between 25-45ft, but unless the very next point recorded is off by 25-45ft in the completely opposite direction it doesn't matter as far as the speed or distance recordings are concerned.

If your locked onto 5 sats and they give you a particular position, but that is 45ft to the left of where it is in reality that is fine. The next position recorded once you move 10ft to the right and are still locked onto those same 5 sats will still be incorrect by the same 45ft to the left of reality on the ground. The GPS will have recorded you moving 10ft, you did move 10ft, just the long/lat positions for the start and end points are both wrong by the same amount. You still moved the distance that the GPS said.

Now during a race you will loose connection to some sats and gain a lock on others which will effect the individual point accuracy along the way, but overall that would be insignificant and from what I'd seen of looking at track logs the one really odd point out of the thousand plus is just ignored in the distance and speed calculations. I've not looked closely at a trace from the 405 in a while though admitedly.

Unless you are doing laps around a couple of cones on a straight road I don't think that the bends are too much of an issue either as none of us are running fast enough that we'd get round those bends in the park in a second such that the line between the points comes up shorter than actuall run.

Krusty_Clown

We're going way off-topic, and this is probably a better discussion for the GPS forum, but I wouldn't necessarily agree. At each recorded point, you can be anywhere within a 'x feet radius'. So there is no reason that your trackpoints will be consistently 10 feet to the left (irregular pattern could be down to anything, like additional tree cover, buildings, etc). Take for example:

Where the blue line is the true route and the red line is the Garmin recorded route. Perhaps the difference in route length is only a couple of inches over three trackpoints (up to 5 seconds), but over the course of a long race, these all add up (.1 of a mile, over a three hour marathon, if the pattern persisted (unlikely though it is)).

Condo131

shels4ever wrote: »

From what I've heard there isnt a huge amount of them to covery all the races that are now running.

Imho, there aren't enough anyway. The same people are 'caught' for measuring all the time...sometimes measuring two or more courses in one day...plays havoc with the training :eek:!

This is the current AAI list of approved measurers.....it's a bit dated, so there may be more trained & approved now. Note that there are large areas of the country with, apparently, no approved measurer.

Measuring established courses isn't too much hassle..apart from traffic and generally starting around 6 am on a Sat or (more likely) Sunday, to avoid it.

The big problem with new courses include preconceived ideas like "it must start here" and, at the same time, "it must end here" - fine if the course is 100% accurate before anyone measures at all. The other main problem with new courses is the pre-selected course may be significantly "out" - have found a 10 mile course "measured" with 4 wheels was actually almost 0.5 mile short. All this can result in a load of 'pfaffing around' looking for alternative routes, or even remeasuring another, alternative, course, on another day, along with doing all the calibrations again.

PS: We've been meaning to hold a measurers training course in Cork for some time, but long fingering has...well..emm...long fingered it . Probably will arrange it in the next three months.

lecheile

Condo131 wrote: »

Imho, there aren't enough anyway. The same people are 'caught' for measuring all the time

Agreed! In many cases though, those guilty of not providing properly measured courses would not be aware of such limitations as they may never have sought a qualified measurer - "Shur aren't dem clocks on de cars that do kilometers fierce accurate now"

Condo131 wrote: »

This is the current AAI list of approved measurers.....it's a bit dated, so there may be more trained & approved now.

There was a course held in Tullamore in April(?) of this year which was filled with a whole new batch of enthusiasts keen to apply their newly honed skills. We'll just need to wait a few years for that to be reflected on the AAI website. Best bet is to contact local county board in the first instance.

plodder

I tested my Garmin on a track once and it measured 401.2 metres, which was reasonably accurate. Maybe, it was a fluke, but even though, each individual point was metres off on the map, the overall path followed the shape of the track and was quite accurate for measuring distance. As I understand it, a significant amount of the error is caused by atmospheric conditions, and that tends not to vary so much over short distances or times.

By the way, when GPS came out first, it was restricted by the military so only they had the most accurate measurements, but that hasn't been the case for over ten years. High end surveying equipment based on GPS can be accurate down to centimetres.

I think it'd still be better to rely on the old technology for course measuring though, as it'd be more consistent as well as accurate (for this purpose). But, a GPS watch would be a useful sanity check, and if someone even cycled that 5 mile course with a watch, they'd definitely have seen it was short.

robinph

plodder wrote: »

I think it'd still be better to rely on the old technology for course measuring though, as it'd be more consistent as well as accurate (for this purpose). But, a GPS watch would be a useful sanity check, and if someone even cycled that 5 mile course with a watch, they'd definitely have seen it was short.

Yep, someone heading backwards round the course during the setup on a bike and they would have spotted the mistake alright.

TFBubendorfer

Krusty_Clown wrote: »

You're right RoyMcC. I went back and had a look through the 405 Garmin user manual (where I thought I'd seen the reference before) and didn't find it there. I actually found it in one of the older Garmin GPS devices I used to have (Garmin Quest).

Here's what it had to say (for that device):
GPS Accuracy Position: <15 meters (49 feet) = 95% typical accuracy
So the Forerunner is a little better than the 5% I previously quoted. Typically when I go running, the accuracy of my 405 would be around 25-45 feet, which based on Garmin's reckoning is probably around 3%-4%. Again, remember, this is the best case scenario. That's why the overall distance/pace is just a curiosity when I run a marathon. I still use a pace band and stop-watch. Garmin's are a valuable aid for training and racing, but they're just an aid.

Now, let's go back to the 1,000 mile challenge, and knock 3-4% off of all the Garmin users.

The most my Garmin has ever been out on a properly measure course was this year's Cork marathon that came up as 26.5 miles on my Garmin - that's still only 1% difference.

I'm absolutely sure your 3-4% estimation is way out (it's inaccurate ). After 2.5 years of using my Garmin I'm absolutely convinced the actually displayed accuracy is within 1 %.

Btw., when I first started using it I found to my disgust that a lot of my standard training courses had actually been slightly short, not long. They had mostly been "measured" using one of mapmyrun's predecessors. If anything, the Garmin now has me run longer, not shorter.

oldrunner

plodder wrote: »

I tested my Garmin on a track once and it measured 401.2 metres, which was reasonably accurate. Maybe, it was a fluke, but even though, each individual point was metres off on the map, the overall path followed the shape of the track and was quite accurate for measuring distance.

I run Santry track every week using Garmin 405 for sessions. It consistently over-estimates the length of the track. In two recent 1500m races (last week and week before), it measured the races as 1610m and 1580m. I believe this occurs because of the infrequency of recording track points. On an oval track this causes problems. However, on long runs with a lot of straight lines, the sum of the errors tends to add up and i get very consistent results both in terms of total distances and mile check-points.

Before people provide the 'obvious' answer - I run close to the inside line in lane 1 - some of the overage will be due to not holding this line but most is down to a technical issue:

Standard 400m track.
Each lane's width is 1,22 m, the measurement is made at 30 cm from the inner border for lane 1, 20 cm for the others:

Lane 1: 400.00 m
Lane 2: 407.04 m
Lane 3: 414.70 m
Lane 4: 422.37 m
Lane 5: 430.03 m
Lane 6: 437.70 m
Lane 7: 445.36 m
Lane 8: 453.03 m

A Garmin will sample track point data typically between 1 to 5 second intervals on a track. There is a sphere of accuracy around each track point reading (determined by sat coverage etc etc). The smarts inside the Garmin try to assume you are running in a straight line unless it can determine otherwise by a couple of consecutive readings. Garmins have a tendency to overshoot on corners usually yielding long distance readings because of this.

The slower you move around a track the more sample points there will be, less overshoot, hence a higher accuracy.

Gringo78

TFBubendorfer wrote: »

The most my Garmin has ever been out on a properly measure course was this year's Cork marathon that came up as 26.5 miles on my Garmin - that's still only 1% difference.

I'm absolutely sure your 3-4% estimation is way out (it's inaccurate ). After 2.5 years of using my Garmin I'm absolutely convinced the actually displayed accuracy is within 1 %

I have 5 x 3km races measured on my Garmin all over the same accurately measured course. Distances measured were 2.99 to 3.08km giving an accuracy of -0.4% to 2.74%. Average is 1% long. On any given day though, could easily be up to 3% out! I've run 31 races with the Garmin on certifed courses and the most its measured short has been 0.4% though. Its measured short 3 out of 31 races. I consider myself to run a pretty good SPR race line.

ManFromAtlantis

i would'nt run a race that wasnt advertised as accurate measure. i know for a lot of people they mightnt care but i do.
but when its advertised as such then it shoudl be. i would be very annoyed if it was too short.

just a small point on the 400m track. someone mentioned that its measure 300mm from track edge. if you wear gps watch on left hand then it might come up a bit short (ok only a tiny bit but still !)