SCSM 2017: How a marathon course is accurately measured

At an IAAF (International Association of Athletics) certified marathon, measuring the race route to the exact centimetre is important, in ensuring that runners do not suffer the post-race disappointment of having inaccurate timings. And at the same time, doing so also maintains the high standards of the IAAF.

But have you ever wondered exactly how the 42.195km distance at a marathon is measured, to make sure that it is exactly 42.195km, though?

I had a chance to find out more about this measurement process and what it entails for myself, when I had been invited to follow the official route measurement process of the Standard Chartered Singapore Marathon (SCSM) recently.

IAAF & AIMS Grade A course measurer Dave Cundy.

The SCSM takes place on the weekend of 2 & 3 December this year.

Measuring the course on a calibrated bicycle 

During the official route measurement process, members of the media had tailed Dave Cundy – an IAAF & AIMS (Association of International Marathons and Distance Races) Grade A course measurer – as he measured the SCSM Marathon course on a calibrated bicycle.

So when Dave had been riding the course on a bicycle, members of the media, together with the IRONMAN Asia staff, had been in a van, following him closely. And to ensure his safety, he had two CISCO police officers accompanying him. This had been especially important when he was riding against the flow of traffic as well as when he was required to cut through lanes of traffic.

Dave taking notes.

IRONMAN Asia are the organisers of the SCSM.

Fixing a Jones counter to the front wheel of the bicycle

Explained Dave, 69, “When we measure the route, we use what we call a Jones counter to fix to the front wheel of a bicycle and this counter just counts numbers and measures in metres or yards. I have to make sense of those numbers. So what I do is, before I start and when I finish, I have to calibrate the bicycle.”

Added Dave, “And to do that, at East Coast Park, I have an accurately measured 300 metre course that I had measured with a steel tape three years ago and I have just calibrated the bicycle against that course. Now I can work out how many counts there are on the counter for each kilometre I ride on the marathon course, and I can then calculate, at the end of the day, just how far I have ridden and work out how far the course is based on that. If it is long, we will find ways of reducing it and if it is short, we will find ways of adding distance to it.”

When I had met up with Dave and the route calibration team at East Coast Park Carpark B1, they had already finished calibrating the 300 metre route and had packed up the bicycles, so I did not see this side process taking place though.

Dave’s bicycle was stowed on the van when he was not riding it.

So we more or less headed straight to Orchard Road, where the Marathon event would begin from. From there, Dave set up his bicycle and then he was good to start measuring the route.

No other more modern way that is more accurate to measure marathon routes

The Jones counter is a system that has been around for more than 60 years, but according to Dave, there is no other way that is more accurate despite the rapid advancements in technology these days.

Said Dave, “Some people think that in these days of high tech, the Jones counter is an archaic way of measuring but there is no better system. GPS is not accurate enough and Google Earth and other mapping systems also lack accuracy. In fact, a university in Perth spent a year doing research on our method of measurement because they thought that there must be a better system in place but after 12 months, they said that the Jones counter is a good device. In fact this is the same system that is being used throughout all countries around the world. So the way that I measured the course in Singapore today, is the same as Olympic marathons and the World Marathon Major races such as London, Boston, New York and so on.”

He added, “This is unlike GPS technology, which is impacted by trees at parks and tall city buildings, which will affect its accuracy. In fact if you have 10,000 runners taking part in a race, all of them will have different readings if they are all wearing a GPS watch.”

The Jones counter on a calibrated bicycle is the best form of measurement.

Jones counter is cheap and easily accessible 

Dave had also explained to me, that the Jones counter is the cheapest and most easily accessible accurate way to measure a marathon route, which is why it was the method selected for the measurement of marathon races worldwide. He said, “Road running is a sport that is conducted in more than 120 countries round the world. So we wanted a system that is affordable for everyone. We do not want to say, have to buy a defence grade GPS system from the United States that will cost you USD$450,000. The Jones Counter costs USD$150 and it fits onto a bike. Every country has bicycles. To measure a calibration course for the Jones counter too, I just need a steel tape that costs less than USD$300. So this is a cheap way of making sure that the system is accessible to everyone around the world.”

An accurate course can be used for world records

Having an accurately measured course though, offers lots of benefits, in terms of setting and comparing world records.

Explained Dave, “One of the great bonuses of having accurately measured courses is that we can have world records, that is a real focus in the media business. The media can talk about expectations and world records – we had that a few weeks ago at the Berlin Marathon. Three top runners were going head to head trying to break the world record but sadly, it rained and they all missed the record. But if we did not have accurately measured courses, then we cannot have records that we can rely on.”

He added, “Being able to recognise world records has brought a media focus to the sport of marathon running. In fact it was not till 2004 that IAAF accepted world records in road marathons; it took us 20 years to convince IAAF that our measurement system was robust enough to compare the different marathons across the world to each other as they are all being accurately measured.”


But there are drawbacks though, with measuring a marathon route, especially when it comes to busy roads and oncoming traffic.

Dave has CISCO officers with him as protection.

In fact, when we had been tailing Dave, there were several occasions when the marathon route brought runners against the flow of traffic, so Dave had to get back back into our van and we then made a detour to the other end of the road concerned – after which, he would then hop back out and measure that particular road from the opposite direction.

Explained Dave, “The most tricky part of measuring is that on race day, the roads are closed to traffic, so runners will have full usage of the roads. But when I am here today, I have to measure the shortest possible route to the runners and that is hard in the traffic, but I do not expect Singapore to close down streets so that I can measure the route. But that is what the CISCO people are for; they will make sure that I am safe when I cut through the traffic to take the shortest possible route, so that we will have an accurately measured course for SCSM 2017.”

He added, “Generally it’s quite hard to measure the city streets as there’s often lots of traffic and where the course bends left or right. It is easy measuring on straight roads when you are riding with traffic, but for bends, I have to hit the apex of each corner. For example at Orchard Road to head towards Prinsep Street, I have to cut across five to six lanes of traffic in a short distance.”

Measurement process is long and arduous 

And then whenever he got back onto the van, too, I would see Dave deeply engrossed in his calculations, with pen and notepad firmly in his hands. This had showed me just how involved the route measurement process had been.

Watching Dave at work, I must admit that I had never realised that the route measurement process was a long and arduous one. From about 9.30am in the morning, to lunch time at roughly about 11.30am, we had covered barely 8km of the 42.195km marathon route.

Measurement process is long and arduous.

I admit that I had initially thought that the process would be a lot simpler and had never realised that there would be so much stopping and re-starting involved too.

Possibly like many others, I had actually expected the route measurement team to zoom through the course quickly in a few hours and without taking any stops. So seeing the events unfolding, had really been an eye-opener for me. In fact, Dave estimated that have taken roughly about 10 hours in all.

When inaccuracies result

And being human too, Dave admitted that inaccuracies may result, though he himself has yet to make an error.

He said, “Well inaccuracies are possible as there is a lot of mathematics and numbers involved. So you could write down a wrong number and make an error calculating. So what I do is to perform my calculations with a pocket calculator and notepad when I am out on the road, and then I go back and put everything into my computer spreadsheet and double check that all of my calculations are accurate. So basically I do the mathematics twice. If I did make a mistake – and so far I have not, then hopefully my checks at night would pick that up.”

Dave is hard at work in the van.

When the route is too short or too long

What does Dave do if he realises that the route is too short or too long?

Said Dave, “It is not unusual to find a course that is several hundred metres short or long; so when people design courses, I encourage them to have a flexible point where the distance can be adjusted. Or they can move the start line or finish line, or else a turning point. Within the SCSM Marathon course, there is a turning point at the eastern end of East Coast Park that is adjustable; so for example if I calculate that the course is 420 metres short, we can add an additional 210 metres to and from the turning point, and bingo, we will have an accurate course. It is that simple.”

He added, “But if there is no such point, then we have to redesign the course. That happened one year for the SCSM Half Marathon. It was a bit short; we were running down Mountbatten Road to Nicoll Highway and to add the distance, we decided to incorporate an out and back loop towards Stadium Way. We went down 200m and came back 200m; that was not part of the original course, but there was not enough room to adjust the route anywhere else. We always have to be thinking about these things.”

Dave takes a lunch break.

Gained interesting insights from the morning 

By the time I had parted ways with the route measurement team, it was lunchtime and though they were nowhere near completed with the process, I had certainly gained some interesting insights into the work required to ensure that the race route is accurate. And so as a regular marathon runner myself, this had indeed been a useful session for me.

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