LAST UPDATED: 2 December 2022

Managing Participant Flows

MMU's Marcel Altenburg walks us through the golden rules for efficient race starts: from waves and start line widths to start pen participant densities.

Marcel AltenburgMarcel Altenburg

Managing Participant Flows

Have you ever wondered how the choices you make about your race start procedure can affect every aspect of the rest of your race? Even simple things, like choosing a wave start over a rolling start, or changing the order and size of each wave, or the width of your start line, can have a significant impact on your race’s safety, congestion on the course, and even your staffing requirements for aid stations and your race finish area.

Today I have the pleasure of having as my guest Marcel Altenburg, probably the world’s foremost expert in crowd dynamics for mass-participation events. Marcel is a senior lecturer at Manchester Metropolitan University and has helped countless races optimize their participant flows from start to finish. Marcel has so much experience in this area and we’ll be going over some simple rules Marcel has come up with from his research that you can use to optimize your race start procedure - whatever the size or type of your race.

In this episode:

  • What is crowd science and how it can be applied to the study of participant flows during mass-participation endurance events
  • How your start line procedure affects everything that happens downstream at your race race course
  • Always try to order start waves by pace (faster runners at the front, slower runners at the back), even if you can't do it perfectly
  • Make your start line 30% narrower than the narrowest point on your course to avoid congestion
  • Aim for a max 3 people per sqm in your start pen for a safe, comfortable race start
  • Keep start waves of slower runners at the back smaller than start waves of faster runners at the front
  • Prefer rolling starts over open starts to eliminate the uncertainty of people arriving at random times
  • For socially-distanced races, keep participants sufficiently socially-distanced at the start and they will only spread out further during the course

Thanks to GiveSignup|RunSignup for supporting quality content for race directors by sponsoring this episode. More than 22,000 in-person, virtual, and hybrid events use GiveSignup|RunSignup's free and integrated solution to save time, grow their events, and raise more. If you'd like to learn more about GiveSignup|RunSignup's all-in-one technology solution for endurance and fundraising events visit

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Episode transcript

Panos  1:59  
Marcel, welcome to the podcast. 

Marcel  2:01  
Hey, Panos. How are you doing? 

Panos  2:02  
I'm very well. Thank you. It's a pleasure to have you on today. I understand that you are quite a busy guy these days in the middle of a global pandemic, being a crowd scientist. So you work at Manchester Metropolitan University which - as you were telling me the other day - is the Hollywood of crowd science. So tell us a little bit about what do you do in your day job? And what do you do as a crowd scientist and also the kinds of problems that you look at?

Marcel  2:31  
Thank you, Panos. First of all, I need to pick that up - the Hollywood of crowd science. I keep saying that because I would have never thought that I'd end up here in Manchester. I'm actually from Berlin, Germany. And I came to Manchester because that is the focal point of crowd science. Anyone who wants to focus on crowds in events or in mass gatherings need to, at one point, learn from our university here, or get in contact, or inevitably come across Manchester Metropolitan University. So it is the Hollywood of crowd science - the one point that everybody needs to come across. And that's also what brought me here - to study here, basically. There's a Master of Science, the world's unique and only Master of Science in crowd dynamics and risk analysis that brought me here. And I stayed here because the university didn't let me go. I supported the course. And now it took over the course. And I'm teaching this Master here from Manchester to the whole world. Like, we have students from all over the world.

Panos  3:33  
And in terms of the work you guys do at the crowd science program, can you give us, like, a brief description of the kinds of problems you look at and what it's all about?

Marcel  3:44  
Yes, 100%. Because we know very well from daily experience that not everything can be solved just by having students in front of us and teaching them the fundamentals of crowd science. Sometimes, you need a solution within days. Everybody who works in events knows that you cannot have a problem and, then, go somewhere to study it for three years to, then, solve it. Sometimes, you need it solved within one season, sometimes, within a few days in order to find a crowd dynamic solution for your unique problem. And that's what we do. We teach, obviously. I mentioned that. But we also have a consultancy aspect where we directly work with race directors, with event organizers, with public transport, and so on. We support them in their changes. We make it part of our research. But we also leave them directly usable advice. We help them implement changes to solve their problems, as I said, sometimes, within days. For me, that's one of the reasons why I stay in Manchester. That makes for me one whole thing. We have a direct connection to the industry. We are part of life challenges on a daily basis. Those lessons become part of our research. So although we might have solved an issue, we still research it. We still make it a part of our interest here because we are a university. And, then, eventually, they will find its entry into teaching so that we can learn collectively because, way too often, it happens that I as a single event organizer have a problem. I solve it. I'm so happy that I'm over this challenge. But I won't tell anyone afterwards. Or I might head to the next problem. And it will never become like a rule that others can apply it, that others can learn by the pure nature of our busy industry.

Panos  5:38  
Right. So what kinds of problems-- for example, in the context of what our listeners would be most interested in, that is endurance events and mass participation sports, what kind of problems are you trying to solve by looking at crowd dynamics?

Marcel  5:54  
Yeah. I gave you three examples. And the last one will be the segue to road races. I want to, first, start with something that's, literally, happening this year - the Expo 2020 in Dubai, like the biggest World Fair Expo ever, record breaking, the biggest budget, things that we have never seen before, in terms of their pavilions and their whole layout. So with all those words that I just mentioned, all those like superlatives, this is not something that you can test before, this is not something that you can take another experience from other events, you need to make it up, build it in stone with a hefty budget, and then it needs to work. So something we experienced alone wouldn't carry the whole way. And that's something that we do. And, then, obviously, we have the luxury of learning from what's happening at this massive World Expo. Another one which is relatable to that would be things like airports. We all know that it's constantly changing - the demand on an airport. Even before COVID, obviously, there are constantly different standards. Every airport worldwide, if you talk to the staff, they're stretched to the limit. And they're all planning the next version of the airport that is-- somewhere down the line, like, maybe, in 10 years, they're going to build a new one. But even though in those 10 years that's between building two new terminals-- in between every year, every month, there are different demands on the existing structure. But you cannot change it. You basically need to grow within your shell like a crab. You need to grow within your shell. Find a new way to use what you have because it takes 10 or 20 years before you can, basically, grow the infrastructure. But you still need to grow within what you have by optimizing. And airports are a great example for that. And that brings us to road races. We call it hyperdynamic in road races - because compared to a theater event, or even airports, or football stadia, in road races - nobody ever sits down. So everybody's moving down the course, or to the start, or out of the finish. So everything is constantly moving. And everybody is moving at their own pace. It couldn't be more like a thousands of ants and all are having the different goal in mind - a different time goal. So we do basically the same. We help events to grow safely, to change safely. It doesn't always need to be a growing capacity. It can also be changed because the city around you change, or you cannot have the course as last year. Something is different than last year. And you need to know what does that mean for the overall movement of 5,000 people, 10,000 people, or more. So those are the things that we look at, where we support great individuals, great race directors. They identify a problem. They can point at it, read, support, and add to the experience, giving us the resources that we have, and the niche interest into crowd science on a daily basis.

Panos  8:57  
So my problems are-- I'm sort of thinking here. You're trying to, sort of, anticipate and solve things like, bottlenecks, or the very crowded finish line, or how people get off the start line. Are these the kinds of issues that you would look at in the context of a road race, for example?

Marcel  9:17  
Yeah. You hit the nail on the head here. It could be like a bottleneck. That's the very obvious one. You might incur a new bottleneck on your course that may be due to a construction site. Like anyone who has a city race or races, they know you need to check for construction site. You even need to check for construction site containers on the road that, kind of, narrow your road all of a sudden compared to last year. So a lot of those things. But it could also be a new course that you need to investigate because, maybe, you have an inaugural race. Or maybe parts of your course can't be used like last year. There are very few races and very few years they can, basically, go with the same plan as last year. But it could also be different things. It could not just be solving a safety issue, it could also be optimization. So when we talk about eight station and staffing, there might be a way to reduce or to optimize your staffing by adjusting something on your crowd flow from the get go, from the start, which could then also, in the end, increase the experience for everybody. If I give an example, if you have like a traveling peak - basically, the peak of the highest density on the course and - some runners, they might be within this peak for the whole race. And they have an entirely different experience than those that are running or traveling behind the peak or in front of the peak. So maybe there is a way to even this out, give everybody the optimum experience, and also make this work for everybody on the course - every staff member, every aid station, every security guy, every guy who hangs medals around next - make their experience better by optimizing the course.

Panos  10:52  
Well, yeah. And you were telling me - actually a really interesting example, which may not sound particularly grand, but you were telling me - how by simulating crowds, I think it was the Berlin marathon, you guys helped trim down the amount of time that roads had to be closed for like 10 minutes, which again, may not sound huge, but in the context of a whole city, like being released to traffic 10 minutes earlier is a pretty big achievement.

Marcel  11:18  
It is. Yeah. That was an example that we discussed earlier which it was in a year that Kipchoge broke the world record in Berlin. But that for me was, basically, the win from a crowd science perspective, the cherry on top, which was by optimizing the crowds there, we were able to reduce the overall flow by close to 10%. So if you would work at an eight station, elbow post finish, you would think, "Hey. This is less. This is not as fast as last year. It might even be less people." But it was actually more people than the year before but the flow was much more even. And that was felt by everyone there. Plus what you just mentioned, we were able to get rid of one wave at the end. So instead of making it five waves, you made it four, which - our research showed us in this particular case - made more sense. It's counterintuitive. That's due to the nature of 45,000 people all on their own agenda, always their own plan in mind. But yeah, those 10 minutes that you can give the road back earlier to the city officials - that makes for a good surprise at the end. It makes them happy. It makes the relationship better. And that shows that you optimize what you're doing. If you have more runners, it's less busy for everybody involved. They're better using their workforce and have a more relaxed day. Plus, you're saving time - that makes for optimization.

Panos  12:37  
And I think, yeah-- And we'll go into some really, really useful tips. You have developed some rules as to what people should be doing at start lines that everyone can learn from in order to make the whole process smoother and everything. And we'll go into that soon. So I was watching one of your talks like two, three years ago or something. And you were explaining the benefits of crowd dynamics. And I remember, back then, you were talking about, "By simulating crowds in a race, broadcasters know where to place the cameras" and everything. And, of course, now having been through COVID, I guess some of those priorities have changed a little bit. So how has COVID changed the focus of your work?

Marcel  13:21  
Yeah. COVID changed the work with road races and also the work with every events. My focus is mainly events and, then, goes into sports direction and, then, obviously-- I'm a runner myself. I'm working with road races for more than 10 years. And I cannot get away from that. And there's lots to learn and also lots to use from other events. And especially with the COVID - our work, mainly, about social distancing started very early at the beginning of the pandemic when - we all tried to figure out what does it mean for us when there were certain restrictions of, "This is how many people you can put in one square of 100m by 100m" or like, "How much space do you need to give everybody in feet or in square meter and so on?" So we needed to assess how much should we give them, actually, in order to see how far are we away from any restrictions, and how close are we, in order to like talk to city officials and prove that we are, either, on the right side already or we can get there. And due to our work with big road races for many years, we realized we actually have this information. We actually know how many people on our course are within 100 meter or 100 yards, or within one minute, anywhere on the course at all times. We do have this information to screen the whole course for people within any bracket of time or space. And that means with the width of the road, we can then, actually, also, make out how much square meter, how much space do we give to every individual. And that gave us the start of a dialogue. First of all, it gave us information for our own planning and, then, we adjusted. While we had to adjust, it gave us the chance to talk to officials, to authorities, and tell them of all the plans - get them onboard - and why there was, in the beginning, a lot of fear, a lot of unknown about the pandemic, and what that means for us. It gave us, very quickly, the chance to talk to city officials, get them on board, and change a lot of those unknown to facts. That might still lead to the result that we cannot have the race but we, at least, know how far we're off. And it also led quite early through the first green lights. Like, New York started in the fall of 2020 - already started to return to racing project - which went over the whole winter and, in the end, will bring us to a, hopefully, successful New York City Marathon at the end of this year. And there's all those races. There's all those research done with us at New York, Chicago and Berlin. And marathons like those gave us a chance to use what we learned there - like big scale races - and take this knowledge and give it to others, share it with our friends and partners in Canada, in Europe, and Australia, and use it for the entire industry. That's a very long answer to your question - what we've done during COVID.

Panos  16:13  
Yeah, indeed. And we'll get into some of those lessons that you've put together in the five golden rules for race starts. I think there's plenty of useful stuff there. One thing to mention here is that all of this analysis you guys do, you make available to organizers through a sort of company that you've spun off from all the research that's called Start Right. Can you tell us a little bit about that?

Marcel  16:38  
Yeah. So first of all, we are University and we want to teach, and share, and research. And that's basically what what drives us forward. And we realized, in the road racing industry, there are like so many races. Every one of them is unique. They have a unique course. They have a unique mission. They have very unique runners that they attract. So while sharing toward lessons or guidance or principles, we also need to find a way to cater individually to this one race with their unique audience during the course. And for that, we developed an algorithm that can use all of those unique information, like information that most race directors have, like timing data, certain course state, and so on. And this algorithm learns from everything we're doing and can give advice. You can look at the course and you can adjust anything. You can put in restrictions. You can put in changes, and it gives you-- it answers your questions, basically. It simulates your race. And the demand for this was quite high. We are supporting around 100 races per year with this service. And there was too much for our university, I must admit for the structures of our university. And so that's why we said, "Hey. Let's have this separate entity that's called Start Right" and that allows us to support races very flexibly. So, like, whenever they need us, sometimes, they call us a year in advance to talk through changes. Sometimes, they call us two weeks before the race and say, "Hey. There's one thing that we need to solve or one thing that we need to prove to authorities. Can you help us?" And we try to be as more flexible than university can be by offering the service.

Panos  18:21  
Yeah, I actually saw some really impressive videos of Grandma's Marathon - I think, shared online of - simulation videos from Start Right where you can actually see, sort of, like, little dots of people coming into the start line in waves then setting off, then another wave comes on. And you can see all kinds of data like, exactly, where the peak density of people is over the course, how they then hit the finish line. So it's like having the race playing out in front of you.

Marcel  18:52  
Yeah, definitely. Grandma's Marathon was in a very unique situation this year. That's the race that happened in Minnesota in June. And they were a race that a lot of people looked at because - there were some races before that but - that was like the first race that was a taster for what the fall season might look like. Fall season, which for our industry, for the running industry is very important. We all, kind of, know that this one needs to work better than last year. So that was the first race that - they already call - is post-COVID which sounds so good, at the same time, so fragile as well. But, yeah. We threw all our support at Grandma's because we knew of the importance. It used this software that I just mentioned, Start Right. It used everything that we learned. I mentioned that we have like, 100 races per year, which is like around a million runners. A million runners' results per year that we're using to teach our algorithm that I would learn from. As much as I love running data, a million is too much for me to fully grasp. So we need to get technology to do that. And all of this improves what we can then use for supporting something like Grandma's. And what we've done there - COVID brought so many things to an extreme - we would normally adjust a start slightly or adjust the capacity of a race by increasing or changing something slightly, like slight adjustments from one year to the next. Now you had COVID. And you had to change on a massive scale so much. And that's what we have Grandma's Marathon to see, "If I change something here, like, at the start, what does it mean for the rest of our course? Maybe there's something big that I'm trying to change only has like, a slight difference for the whole of the race. Or maybe it's something tiny that I can change that doesn't cost me a lot. But it makes a world of a difference down the line on the course." We sometimes compare starting a race with a water tap. I can do so many things at the start. I can open it entirely with a lot of water, a lot of runners coming out. And, then, close it again. I can do it in waves. I can just open it a bit and let them trickle out. And all of this will have a difference for the course. Or a different spot, a finish which is 26.2 miles away, which is-- I'm doing nothing else everyday other than looking at road dynamics. But seeing what the change at the start makes - for a difference of 26.2 miles away - is really hard to spin your head around. You need some calculating power and experience to do it. And that's what we had Grandma's with. Their race was successful. And conditions improved since then. And conditions are evolving and changing. And, yeah. They gave us good hope for the fall season.

Panos  21:47  
I guess what you're saying there is that, if the course is what the course is and, then, runners are people that - depending on their capacity, they - can run faster or slower, really, it all comes down to how you manage the start line. That sort of affects everything from that point onwards.

Marcel  22:05  
It is. And, also, I always say, "It's the last time they listen to you." Like at the start, your team members - it's early in the morning - they are at the end of their training at the start of the race. They are listening to you because they want this to go right. They don't want to waste a second. They want to do the right thing. They want to go but also not want to go. But once they go crossing the startline, that's it. They're not gonna listen to you anymore and they shouldn't. They should do their thing that they came for - an uninterrupted race. They shouldn't need to stop anywhere because it's a tight spot or because you need them to do something. And they should run the entire race. So the last time that you can change something for every individual is before the start. And runners really listen, really cooperate, and they do what you said at the start. And, then, they should do their own thing. And all of those runners with their individual time goals and their individual career that they started, they all together make the flow. There's a lot of mixing, a lot of things happening within the flow. And to get this right, you only have that chance at the start. And, then, the rest is hopefully, hands off, watching what's happening. And you don't need to adjust anything along the way. 

Panos  23:20  
Yeah. So let's look at the start line then. And let's look at what as you were saying - more than a million data points with runners and hundreds of races have taught us - about how different choices of how you start your race lead to different outcomes, in terms of people traveling through the course and finishing. And you have put together a set of five golden rules, in terms of what you can do for your race start to better manage the flow of people and keep everyone safe and distanced. So rule number one you have on your list is, "Make sure you order your field by pace." So I guess you're saying, put your fastest runners at the start and, then, the slower runners at the back.

Marcel  24:15  
Yeah. We really wanted to share something out of what you just correctly mentioned - more than a million runners and data sets per year. So we're constantly learning from this and that is research that was done over last five years. And there's a report to this - like, I think, 200 pages by now - and the software and so on. But we wanted to share this with everybody and that's why I'm so happy to be able to like share this with your audience on this podcast and also in writing to really give away some of the lessons that we learn from this research. A lot of things might sound familiar and might be intuitive. Others are may be counterintuitive. But this gives a race director some signs, some proof to their hands to, basically, prove their intuition and ensures that, "Yeah. You are you on the right track and we can explain why," and to share this with, like, races of any capacity. And that's what this works for-- the first point is order. That is true - doesn't matter if you have a 200 people race or a 50,000 people race, if you can order them, from fastest to slowest, that will be the ideal, because that makes perfect sense probably. When you think about it, it reduces the number of overtakes on the course. If I have the fastest in the very back of, like, maybe, a 200 people 5 km race, probably, the fastest will end up the first but he needed to go through all the 200 people. And this works to any degree. If you put him somewhere in middle, he only needs overtake 100 people, and so on. But the main point here is you will never succeed, probably, in ordering them perfectly because people have, maybe, a bad day or good day, or maybe you only have three waves. You order three waves by pace as best as you can. But then within the waves, you cannot really order them without breaking that down. But that is not the point. The point is any order helps. And even if you have your five km with 200 people somewhere in the forest, even if you break that down into two groups, just bring a bit of order. It will help because it increases the degree of order. We're not talking about having an order or not an order - that's not the point. The degree of order by any bit helps. And if a race of 20,000 says, "Hey, we will up the number of corrals or pens that we have and order them a bit more," that will have an impact. And if those volunteers at the entrance of every corral, they make sure to double check and help people, "Hey. You're here in the wrong corral. You're in the wrong pen. Yours is over there." They will make sure that everybody is in the best possible position throughout the entire race among folks that have similar ability. He won't be overtaken that much, which is stress for you. And he doesn't need to overtake as much which is also stress for him and for everybody who needs to run pass him. And to wrap this up, there were - races where every individual was involved in a thousand overtakes, like we can measure all of this, so - prominent city races where people were able to be involved in a thousand overtakes either by people coming past them, or they having to find their way through the crowd. And, then, we are able to reduce this to around 200, maybe 300. You get a feeling of, like, how that helps every individual to have a more relaxed day, be more in tune with their own ways. But, also, every time people overtake each other, they're running abreast for a second or two. And when they're running abreast next to each other, I need more course width. So there's an absolute benefit, basically, of ordering them just a bit so that they don't try to go through another section of a course just when they're overtaking, by reducing the number of overtakes. 

Panos  28:05  
Yeah. And, of course, less people overtaking is also, generally, good for health considerations now - with COVID and stuff. Like, the less you get people to be close during the course, particularly, when they're sweating and stuff, it's good to avoid overtaking as much as possible

Marcel  28:22  
100%. You said that absolutely right. And my main point is here - any degree helps. So any volunteer at the start, you can make a difference to the whole race. If you're at the start, send a couple of people in the right pens and, like, focus on that, you can change the whole course, you can change the whole finish long after you're part of the event that you were responsible for is over. The result of that will still be fair. And if you are race that thinks about, "Should I have corrals? Should I order them a bit?" Yeah. Any degree helps. You don't need to change the world but just any bit. That's what our research shows. And I think I went into enough depth fear to make that point,

Panos  29:03  
I guess you would order people either through past data or most likely, sort of, like, self declaration stuff. So you collect information. I've seen it on registration forms where you'd ask people, "What's your pace? Or what's your expected finish time?" What about people that you don't have data for?

Marcel  29:22  
Yeah. That's a very good point. So that's what I mentioned, like any degree is beneficial. And that could either be by proof of times, like a 10 km time or a half marathon time and so on, or by projected finishing time. It doesn't really matter. As long as you ask everybody the same thing, "Do we have an expected finishing time? Or do we have proof of one thing?" They will find a way to order them. Any order that you don't do at the start needs to have on the course. That's what overtaking is. If you will let them run for a thousand kilometres, in the end, they will arrive very exhausted, but they'll also arrive in the perfect order. So if you are able to do this at the start, even better. So those who you don't have data points, maybe, you can ask them, what are their career times, like of a 5 km and 10 km. They don't have a half marathon time in this example. What you shouldn't do - put all the newbies, all the first time runners in the last wave. That would be not a way of ordering. That would be a way of logistically managing it that would cause disorder, like, more than necessary.

Panos  30:29  
It's interesting because, actually, I was about to say that's exactly how I've seen some races I've run in the past manage people without times. Usually, what they do is they put them all at the very last wave. I guess you could have people of all kinds of abilities in there. And, I guess, probably for logistical reasons, as you say, they just throw everyone at the back of the pack, which may not be optimal, perhaps.

Marcel  30:56  
Yeah. I've been in those corrals in the back as well. That was long time ago. Now, there is-- I don't know. You cannot even walk without something on your body counting your steps. So if there is any way to assess that - it doesn't need to be perfect and - that can be used.


Panos  31:17  
While we're on the subject of managing crowds, one of the areas that always gets people concerned is packet pickup: "Is it going to run smoothly enough?", "Am I going to get everyone checked in and on their way fast enough to avoid getting those long check-in queues people hate?"

Well, GiveSignup|RunSignup have really made an art of race-day check-in, and with their free RaceDay CheckIn App the process of checking in runners and getting them their swag has never been more efficient. You can quickly get people checked in with pre-assigned bibs, if that's what you like to do, or you can use the amazing dynamic bib assignment functionality.

What's great about that is, instead of frantically looking for the right people on race-day, you can assign runners bibs at pickup - whatever bib might be on top of the pile. All the runner has to do is come up to the table with their QR code from their confirmation email on their phone, get it scanned by one of your volunteers, and they get a bin number assigned to them instantly and their swag order delivered in seconds.

And you know what the best bit is? With dynamic bib assignment, there's no more wasting bibs on no-show runners. You only give out the bibs you need to the people actually starting your race - no waste and no money down the drain. It's so neat how much you can do with technology these days that we should actually probably dedicate a full episode on just race-day check-in.

But that will have to wait. Now, let's get back to discussing more of Marcel Altenburg's golden rules for efficient race starts. 


Panos  32:50  
So rule number two for efficient starts is that your start line should be 30% narrower than the narrowest point of the course within the first two kilometers. So that's pretty specific. That's also something that people would have guessed. How did that come about? And like what's, sort of, like, the logic or the intuition behind that?

Marcel  33:15  
Yeah. That's basically the first challenge that we had when we did our big research on crowd flow. Our first main challenge that was thrown at us when we tested ourselves again was like, if we have a pinch point on the course and - there was an inaugural race that we had here in London and there was a pinch point on the course and - the question was, "How to fit through the pinch point?" which led us to what you mentioned earlier, "How to start?". That has been the main challenge. And on a big scale, we solved this with an algorithm. But there are some-- if you don't need the algorithm, or if you have that may be a bit too specific for the size of your race. This is a good rule of thumb to go by. And what is behind that is, obviously, before the start line, people are at a higher density than they can run. Let's forget COVID for this example. People are standing quite closely to one another. They're listening to some good tunes. There's a countdown. But they are standing at the density that is not normal that wouldn't work in a supermarket and definitely wouldn't work while running where they need more space. In order to give them that much space, you need to give them based on the course, based at the end. That's what you do here. So if you reduce the start line, basically, to go back to the example of a water tap, reduce how wide you open that tap, that means they are trickling on the course slower. So when less than, let's say, a thousand people entering the course in a minute, it may just be 700. And those 700 that are entering the course within a minute, they now have more space than it would be a thousand in the same minute, basically. And that space is vital for them to be able to run. Like if somebody is too close to me, I cannot fulfill my stride, which I might do more than two and a half meters per second. So I need that space in front of me, physically, in order to be able to run and have a quality experience. But the crowd science lesson that is behind that is you need to give people space before they can move. Sometimes, in the event world, it's been the other way around. People moving to create space. That's not the case. It's the other way. It's like we need to give people space in order to move. That's what we do on here. By reducing the flow - like, instead of opening the tap entirely, open it just to 70%, - that means they do have enough space to run at their pace and to fit through anything on the course. That is as precise as we can do to fit it into a few rules. When we calculate something like this for, let's say, Chicago Marathon, or Berlin, or New York, we screen the entire course. We have precise measurements of every bit on the course. And we check the start against all those pinch points on the course. That was done with pen and paper, maybe, eight years ago. And, now, we do this 12 million calculations to be really sure that everybody fits through there. But in one sentence, "Yes. 30% less than the narrowest point on the course should be your start line." And one last thing, this doesn't mean that the start entry needs to be 30% less. It can be a pinch point before. It can be like a funnel before you actually start entry. So start entry would be, let's say that, your sponsor is written on there. And you have a standard format over the course of the road, over the whole width of the road, and it says your sponsor - you can leave that, that's not the point, but - 10 meters behind that, or 5 or 20 meters behind that, you can have a funny bit of fences. And that should be those 30% less.

Panos  37:02  
So, basically, at some point during the start flow, just make sure there's like a funnel there, as you said, which is at maximum 70% of the narrowest point in the rest of the course. So rule number three, you're saying, "Keep the density of people within the start pen at a maximum of three people per square meter." So my first question on that is - is that compliant with, like, typical COVID distancing requirements these days?

Marcel  37:35  
Not with COVID. This goes when we, hopefully, return to racing, mainly, as it was before. Then you will need to put three people per square meter. As I said, I need space in order to be able to move and that's what we achieve here. There is some guidance out there that says four people per square meter which we, from a science perspective, can say it is wrong, it doesn't work. So although there might be numbers circulating out there, no race ever does that because it doesn't fit, it wouldn't work. Three people per square meter - that's something that we want to give race directors a number at the hand that is scientifically proven, and that they have a basis to plan on. So three people per square meter is good. Very quality races, they go to 2.1-2.3 people per square meter. So they give them even more space, which we found in surveys, that's very well received by the audience if they do have this extra space at the start. As four people per square meter, I invite everybody to try it at home - four people per square meter - try to tie your shoes if you stand in a quarter of a square meter. It's impossible. So that is a safety aspect. So here in this case, I mentioned to you before the podcast that we do a lot of work also with stadia, like football clubs here like Manchester City or United or by Munich. And this is something that comes from their neck of the woods, that comes from the world with them. Like, how much space do I need to give people in order to feel safe, very important? So even if something would go wrong, they won't react in a stressed way, but also be safe. And we're talking about emergency here. I'm talking about evacuation. I'm just talking about general safety that if one person falls, that doesn't mean that everybody falls like a domino. And three people per square meter is safe middle ground between using my space efficiently, but also giving everybody a safe space no matter how big my race is.

Panos  39:36  
Do we know what that number would look like these days and the COVID-- like, what that density would look like to adhere, for instance, to what we have in some places in Europe, like two meter rule of social distancing or six-feet or whatever they have in the US?

Marcel  39:53  
Yeah. That is a very cool topic because that is what makes or breaks a race. I need to give them 10 times that much space than we've talked about here for, let's say, two meter social distance. When there's a queue in front of my supermarket here in Manchester because of social distancing - that's one thing that - the queue is now longer, maybe, double the length than it was before without social distancing. But if I have a crowd, I now need to keep the distance, not just to the guy in front of me, and the guy behind me, I also need the distance now to everybody left and right of me. So the space is growing in both directions. So if I double the distance, instead of one meter to two meter, let's say, we had this change here, so this is a life example, we had to change here in the UK - one meter distance and two meter distance - for a roadway start. That will be quadrupling the space they need just because they need to go in both directions. And that is even without a safety buffer. And that makes it, very quickly, not a viable undertaking anymore if I need to give them four times as much space between one meter and two meter - or in this case, between normal and COVID - to six and ten times that much space. Like, you wouldn't find that. I don't know your specific ways but I doubt that you'll find an extra 10 times that much space.

Panos  41:16  
So, basically, you're saying that the two meter rule, if you really try to design, let's say, a grid of people that appear two meters between all of them, you'd probably be looking at - if you said 10 times more - something like three people per ten square meters or something, which is quite a lot.

Marcel  41:34  
Yeah, definitely. So yeah, that's what you would look at. And all these, like, fulfill those rules. And that - will be found that, basically - broke a lot of people's event because what we also found in our research that social distance, if we're looking at like, one meter, two meter, or three meter on the course for all our road races, we looked at a hundred races just last year again and they all fulfilled socially distance requirements on the course, having five meter, ten meter distance between runners, it is a start that needs to be nailed, post-finish, and on the course. Road races don't have that problem. They fulfill the requirements. It is the start aspect where you need so much more space. And the difference between two meters that we had here in the UK, and 1.5 meter that we had, let's say, in Germany, or parts of Europe - that is massive. As I just said, like the quadruple of distance plus multiplying it with the high number of participants can make or break an event. So when we change it here from two meter to one meter in the UK, that is a different world entirely. And even the difference between six feet, which checks out at around 1.80 meter to 2 meter difference, that is making such a big difference on a large scale more than-- I sometimes think those rules are introduced for good reason. They seem to be super even, more even than scientists would do it - the one meter two, meter something. That's easy to digest. But just centimeters here per person changes if a race can go ahead or not.

Panos  43:13  
So in terms of having to do race starts with some degree of social distancing that goes beyond the normal distancing, you would allow in your rule three of, where you said, like, maximum three people per square meter where you, sort of, deduce this number more on the basis of keeping people comfortable on the start line, but that was pre-COVID. Have you seen any special protocols being put together for race starts that would allow racers to start with social distancing at even large races?

Marcel  43:50  
Yeah. We have a lot of races put in a social distance start with different formats - could be time-trial start where like, five people set out every few seconds or where individual corrals have like 100 or 200 people set off at one goal and then there's the next ones. Or maybe even all of them walking up, like call it zombie walking, to the start to, like keep that distance. And we help them with that. And I'm so happy to say that we also have, again, races in the US and in the UK, and also parts of Australia where we can go back to those three people per square meter. We had 10 km race last weekend, which was a mix of a hybrid between social distance and non-social distance which was part of the test that was run by the government. And they luckily go back to those rules before COVID. And people luckily react the same way to it. So when we say here, three people per square meter was safe before COVID, we now have proof or we now have evidence that this will still work post-COVID and will get people the environment that they'll feel safe and that they'll react the way we knew them before.

Panos  45:06  
So, by safe, you're talking about the reunion 10 km or something, right? The test event, I think that's what it was called, that the government put together in the UK. Are you saying that even when, nowadays, you start people with the three people per square meter density, this event still ended up being safe from a COVID transmission point of view, or from, simply, like people keeping safe and comfortable general point of view? 

Marcel  45:36  
From a COVID transmission point of view. There will be a report on this. This is something for the medical side to release but the indications are all quite positive. And the team have the luck, math and who were behind those test events, they did a fabulous job of putting all of this together. But here the density aspect, again, let's say that this is post-COVID - hopefully, we can return to something like this - how tightly affect them makes a difference for, first of all, how safe they are and how safe they feel. And I just want to give you two examples on this. If I put like, four people per square meter, or five, and I give one of them a push, or one of them lose their balance, they will all fall. And if my whole staff could have falls because I packed them too tightly-- and I can invite everybody to look something like this up on YouTube to look what this looks like at the concert where we can learn from or a gathering to watch football publicly. And this is not something that you want to have in your start corral. So three people per square meter is something that means nobody gets crushed, to be very dramatic. And nobody to fall because the guy next to me falls because I have enough space to make the step to catch myself before I fall into next person. And that's a reality that we have now and we'll also have after whatever the reality looks like post COVID. There might be, sometimes, moments where I need to work with my crowd. I give an example and that might be a delayed start due to something that I need to figure out on the course. I don't want to mention a word terror here. It could also be a water pipe breaking somewhere - that was an example to orientate on, so - something that forced me to lay the start just to get something off the road somewhere. And we all know that, let's say, if I go to a library here at my university, I know what the library feels like, how much space I would have at the library left and right of me in order to feel comfortable, take a book out and like read in it, or in the subway, like on the train or on my way to university to the library there. I accept an entirely different close contact to people that are packed within one carriage in the subway. So there are two different scenarios in which I accept the different density. So if somebody would come that close to me in the library, or if he just stood next to me in the subway, it would feel uncomfortable. It would affect my sense of safety. And the same is true in a start corral. So if I ask people, we need to lay the start by five minutes, and it may even be raining, and they might not know what's going on, if they have a space that they feel safe in - and that is what we found out, like three people per square meter - they are more cooperating with me than if somebody is breathing in their neck and I'm asking them to endure this 10 minutes longer and I can't even share with them fully what's going on. And in order to keep them physically safe, and keep them safe in order to cooperate and feel safe, that's the value. And I'm happy to share that we saw three people per square meter already, like, not too long ago, just days ago. And I'm really hoping we will return to this reality.

Panos  48:50  
Yeah. Well, so does everyone, I think, listening in. Well, moving on to rule four - you're saying, I think, we shouldn't dwell too much on that because it's something we've touched on already, which is your rule four is - stick to wave starts. Wave starts help. Yes, definitely. So rule five which is also quite specific and - at least to me, it sounds a little bit counterintuitive - you're saying waves should get smaller towards the back of the pack. So what sort of like the science behind that? Why would you have slower waves at the back than at the front?

Marcel  49:29  
So in an ideal world, I wouldn't need waves because everybody is ordered perfectly by pace. And if everybody's ordered perfectly by pace like in a, let's say, a small time-trial at the telephones, maybe, nobody should ever overtake the next one because they're ordered by pace and they're getting on the course with some distance. So no single overtaking. But that's not the reality. And because I cannot order them by pace, I should stretch them out in individual waves and not just ordering them in pens and corrals. It makes sense to put some minutes in between. If I do have the time, like three closer time, I should put some minutes in between. And that means I understand and accept that I cannot order them perfectly. And that's where waves add to this effect. So they're basically substituting the order. And, inevitably, the first one of the second wave will, at one point, catch the last one of the wave before and, then, they start mixing. So I delayed the point when they start to mix and order in a new order. I delayed this point a bit. That means, overall, it will be less overtakes on the entire course compared to letting them do this safe ordering process from the beginning. That's one point. That's by waves unless you have the perfect order which I would love to see the data if you've achieve that. And we are working on trying to get the property audit race. But unless you can achieve that, waves really help. And that brings us to this rule number five, that waves to the back should get smaller. Reason for that is, in the front, I do have fast runners and they normally stretch out better cause there are different people with different abilities. If I like, let's say, have a half marathon, it could be that if you run sub 90 minutes, you're still in the first 5% of the overall race. So the big aspect of the race, 90 minutes to maybe a total of - most races go to - 3 hours 15 minutes of a half marathon, that's where the majority of the race is. So I don't need to focus too much on the guys on the front. First of all, they know their predicted finishing time very well down to the second, like what their ambition is today. Their racing streamlined and they stretch themselves out because it's less people per individual minute that they're even able to run that. And that changes entirely to the guys in the back. Those men and women that are running there, they don't know that time exactly. They sometimes round to the next full 30 minutes. And I need to counterbalance for that. I need to take them apart and put them on waves. They also cling together. And they sometimes run in groups more than the individual. This is individual unique goal would do that. And plus, yeah, they are much harder because I have more people around my four hour mark, around my five or three and a half hour mark, and I need to spread them out more which, again, I need to do it at the start because, on the course, they might stick together more. And I know the reality is completely the other way around. I know my sub 90 minutes, sub 100 minutes-- just stay with my half marathon example, my sub two hours and, then, the big race where it's hard to put a handle on them, those are exactly the men and women that I should put into smaller waves. And we mentioned that multiple times now, order is scientifically the best way to do it, and reducing the tap at the start, and everything that I can't perfectly order, that will be my waves - smaller waves to the back, bigger waves to the front. That will solve the problem on the course. They will order themselves on the course and there's a space to do that. But the focus should be on those guys on the back. And they will appreciate if I improve the running experience for sure because to face it, they are also our main audience. Kipchoge is great. I love the men. Our main audience are the thousands and tens of thousands in the back of the race where, sometimes, the atmosphere is much better. And you help them if you allow them smaller waves.

Panos  53:37  
Perfect. So let me just summarize for everyone the five rules for efficient race starts. And again, hopefully, we'll get this out into a document for everyone with a little bit more detail. So rule number one, order your field by pace. Rule number two, make sure your start line or somewhere along your start line, there is a kind of funnel that is at least 30% narrower than the narrowest point on the course. Keep it to a maximum of three people per square meter at the start pen for just a safe and comfortable race start for everybody. And this doesn't assume social distancing so you may want to adjust that. Rule number four, do wave starts - obvious. And then rule number five, try to keep the waves at the back of the race smaller than the waves are at the front of the race. Perfect. So let me put to you a couple of questions we've had in our race directors group on Facebook. Yeah. Again, around starts, another kind of like crowd density crowd dynamic questions that people have, so some people - and it's a few, seem to, during this COVID period, they - seem to have ended up doing what they call open starts. So, basically, a start procedure where, basically, you keep your startline open for like, three, four hours, or whatever. And then people show up and whenever they show up, you sort of, like, roughly make sure that they're distanced and then you let them go. So rather than tell people, "You're on the 9am wave" and "You're on the 9.10 am wave" or whatever, people seem to find it - a little, I mean, logistically, maybe it's easier but, generally, it's - quite efficient to do these open starts. And other people are saying, "It's also quite efficient to be doing rolling starts" which I guess is what you're calling like the zombie walk before. Do we have any like data or insights into whether open starts or rolling starts work well for start lines?

Marcel  55:43  
Yeah. We have loads of data now on rolling starts and that they do work. And they also do work efficiently. With open starts, yes, we also saw that working. However, it is less efficient because it's more degrees of freedom that I give to the runner, basically. So whenever I give people degrees of freedom, I need to cater for both options, basically. So to keep my race efficient, and from a course perspective, and also, depending on the restrictions that I have, and what I need to prove to my individual authorities, I might need to put a bit more control on it. And that brings us back to the point of order. Order always helps. And if I give people a start time, even if it's a rough one, even if it's a very loose one, like show up within this half an hour window, and the next people, I give them the next half an hour, even that helps. So any degree of order here prevents unforeseen surprises. And it also prevents that I need to plan for everybody to just freely do what they think is right because then I can be surprised, maybe, for some reason, some unforeseen train that leads to a perfect time to my start, they're all coming at the same time after the morning news, or the morning breakfast, or whatnot. Yeah, both can work. The safer and more efficient one is the rolling start and giving at least rough time windows. And that's something that-- that's a lesson that we learned before from airports and from football stadia who were luckily able to open much before road racing events. And they have also really help to give people-- and we saw the difference and we saw the data behind it if people have an arrival window.

Panos  57:31  
Another question we get is, nowadays, when local authorities demand races to adhere to some kind of social distancing pattern, or like to put some measures in place, that has repercussions for the maximum number of participants that a race can have - if you have that, for instance, and also how long you can be on the course, it sort of limits you overall - is there a quick, sort of, like, rule of thumb or quick calculation that people can put together to deduce how they can think of the maximum safe number of participants at these times where we have COVID, and distancing, and other effects? 

Marcel  58:12  
There is a quick rule that can be used and that is in all races as we looked at over last year - and you're right, we were quite busy - on the course and post finish. As long as they keep moving post finish, they all fulfill any social distance requirement that we have seen. We have seen different ones like how many square meter everybody needs, or how much distance they need to keep - you mentioned, one meter, two meters and more, so - on the course and post finish. That is not the first thing people need to worry about if they are organizing road race - it's the start. And just by giving this clarity and this reassurance, that breaks down a massive problem to one that, at least, focuses on one point. And at the start, people aren't moving that much yet. So if you can figure out how many people you can fit safely in your start, whatever that means, in your individual situation, or how many people you are allowed to - maybe the government helps you with that, like they give you a facility, sometimes they give a number that they see fit there, and the course with it - that's the reassurance that we can give. And there's also a lot of research behind that that we can share. If you can figure out your start, the rest will likely fall into place, which then can also be proven by the first point where we started. And we saw very creative examples here where organizers said, "Well one start area doesn't cut it." So we have three start area and they roll together into one course which gave them three times the capacity and we help them figure out to prove what I just said, like the course is still not the problem. You need to have increased start width in this start area even down to more than one race changing the direction of their course because they realized their finish is bigger than their start, and they need the start space. So they basically ran the same course the other direction to solve that problem. And, then, course and finish is still a challenge but it fell into place. And it's much more forgiving in our particular industry, which is very different to festivals, and so on. So to start a little bit that's optimal.

Panos  1:00:24  
Yeah, so it's interesting. So, basically, you're saying that if you want to work out the maximum number of participants that's safe for your race to accommodate even with distancing rule and everything, your point, which is really important, is you can reduce that whole problem about what's happening in the race and the finish line and everything so long as people keep moving, and just thinking about how many people you can start safely at the start, and how many people you can safely accommodate at the start. If you work out that problem - which you can, I guess, work out - from just the geometry of the thing, and how long your start line is, and how much time you have to start people off, if you work out the start where everyone is also static, which is a little bit easier, then everything else takes care of itself downstream.

Marcel  1:01:11  
I couldn't say it better because you basically break down a whole operation to at least one picture. You said it is a static one. It isn't like everybody moving at individual pace. It simplifies it a bit. Like, as I said, a three digit number of races all fell into place from there if you can solve that one aspect. And we can prove, then, what that means for the course so that you can present it to authorities or internally. Like, once that stuff is figured out, we can look at the next thing but I am quite sure that will be okay.

Panos  1:01:41  
Right. So we mentioned earlier at the top of the show the work you do for people through Start Right. We've also shared some rules that anyone can use. In terms of Start Right, how can people get in touch with you if they really want to take their analysis of the crowd dynamics in the race a step further? Is there a way to contact you?

Marcel  1:02:05  
Yeah. So you can google Start Right. Or you can google my name or It brings you directly to the web page that gives you more background information and they can also reach out and get that support. Our idea is to really hit every size of the race. And, maybe, you find enough in those five rules-- I'm like, again, super happy to share this with you and especially with your audience while on your platform. Maybe, that is what helps you to support you in the right direction. And if your race or your problem is too complex that those five rules are not enough, then you can get in contact and we can solve that then. Because a big race can by now only be taken apart by big data by the right algorithm that exceeds what we can do. With all brains, we can bring the logics but then, at one point, the numbers need to be run. And what we offer is support to your next race based on a flat rate. As a university, our mission to, like, help this transparent and low costs, any race to, in the end, help the entire industry by bringing those lessons forward.

Panos  1:03:20  
Perfect. Well, that's been really helpful, I think, for everyone listening in, in terms of both how you can manage an efficient start line when things go back to normal, and also some special precautions that people can take during this very weird times we're going through. I'd like to thank you very, very much, Marcel, for the time you took to share all of this with us. There's the contact details there for people who want to get in touch through Start Right. You have also very public profile at the Manchester Metropolitan University. Thank you very much for coming on the podcast today. I really appreciate it. 

Marcel  1:03:57  
It was an absolute pleasure. Thanks for inviting me. 

Panos  1:03:59  
And thank you very much also to everyone listening in and we will see everyone on the next episode. 


Panos  1:04:11  
I hope you enjoyed this episode on managing participant crowds with Manchester Metropolitan University crowd scientist, Marcel Altenburg.

You can find more resources on anything and everything to do with putting on races on our website You can also share your questions about start line procedures, participant social distancing or anything else in our Facebook group, Race Directors Hub.

If you enjoyed this episode, don't forget to hit "Follow" on your favorite player and do check out our podcast back-catalogue for more great content like this.

Until our next episode, take care and keep putting on amazing races.

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