Fire Science Show
Fire Science Show
212 - A glossary for evacuation with Enrico Ronchi and Ezel Üsten
When experts from different disciplines attempt to collaborate on complex problems, such as evacuation modelling, we often discover that we're not speaking the same language. Even seemingly simple terms like "density," "velocity," and "distance" carry dramatically different meanings across physics, psychology, engineering, and computer science.
In this episode, we present the "Glossary for Research on Human Crowd Dynamics," a remarkable community effort that brought together over 60 researchers to create a shared vocabulary for those studying human movement in crowds. In this episode, I speak with two key contributors to this project: Professor Enrico Ronchi from Lund University, who helped organise the original workshop that spawned the first edition, and Ezel Üsten from Jülich Forschungszentrum, the corresponding author of the newly released second edition.
They reveal the fascinating process behind creating consensus among diverse scientific perspectives – from the intensive week-long workshop at the Lorentz Centre where the first edition was born, to the year-long online collaboration that produced the expanded second edition. We explore how the glossary handles controversial terms like "panic" (often misused in media and research alike), unpack the nuances of seemingly straightforward concepts like "fundamental diagrams," and discuss why the absence of citations was a deliberate choice to prevent territorial disputes.
What emerges is not just a practical resource for evacuation research but a blueprint for how scientific communities can build collective understanding across disciplinary boundaries. As we face increasingly complex challenges in fire safety engineering, this kind of "community wisdom" becomes invaluable. Whether you're a researcher, practitioner, or simply curious about how experts bridge communication gaps, this conversation offers rich insights into the power of shared language in advancing our understanding of human behaviour during emergencies.
And here is the link to the glossary: https://collective-dynamics.eu/index.php/cod/article/view/A189
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Hello everybody, welcome to the Fire Science Show. You know I'm big on promoting good communication in fire science and outside fire science. How to communicate fire problems to all the stakeholders is one of the main challenges that we have today and that the future fire protection engineers will have to be better at. Simply that is. But communication good communication comes with some prerequisites, and one of those prerequisites is that we actually understand each other, which is not necessarily granted, especially when we talk about technical terms across multiple disciplines. Often than not that you have to talk to your colleague who specializes in computer science, you have to talk to an architect, you have to talk to an electrician, someone who's managing water supply, etc. There are some terms, even very basic terms, that will be understood differently by those people. Therefore, having some sort of a shared glossary is an extremely, extremely useful tool for our practice. For fire safety engineering at large, we do not really have a shared glossary. There are some stuff like ISO standards on nomenclature, etc. But it's not what I'm talking about in this episode. Today's podcast episode is about glossary for research on human crowd dynamics. It's a second edition of this glossary and it includes a lot of stuff related to evacuation, which is, of course, a huge part of fire safety engineering. And, what's interesting, this is a community effort, a bunch of people that sat down together and agreed on how we should refer to some very basic, fundamental, most important terms for the human evacuation or human crowd dynamics research. As the second version has been published in open access and links are, of course, in the show notes, I've chosen to invite some people into the podcast to talk over why you did and how you actually manage building a glossary that's useful for the whole community and, as I said, it's a massive effort. So the list of authors is is incredible, and the organizing committee itself that's julianne adrian, nicolai boda, thomas Chattagnon, alessandro Corbetta, john Drury, claudio Feliciani, anna Zibin, enrico Ronchi and Ezel Usten. And out of this very, very long list of amazing people who committed to this resource, I've invited Professor Enrico Ronchi from Lund, who has been in the podcast multiple times and he has been involved in organizing the first meeting that started this glossary, and well, you'll been in the podcast multiple times and he has been involved in organizing the first meeting that started this glossary, and well, you'll hear in the podcast. And I've also invited Essel Usten from Jülich Forschungszentrum, who is the corresponding author of the second edition, so we have a good representation from the origins of the resource, from the recent update of the resource tells a lot of interesting things. You will learn some stuff about evacuation, some stuff that we perhaps understand differently than others. You'll learn how to build a glossary. You'll learn how a great community project in the sphere of fire safety engineering looks like. So very worth it. Stay with us. Let's spin the intro and jump to the episode. With us, let's spin the intro and jump to the episode. Welcome to the Firesize Show. My name is Wojciech Wigrzynski and I will be your host.
Speaker 1:The FireSense Show is into its third year of continued support from its sponsor, ofar Consultants, who are an independent, multi-award-winning fire engineering consultancy with a reputation for delivering innovative safety-driven solutions. As the UK-leading independent fire risk consultancy, OFR's globally established team have developed a reputation for preeminent fire engineering expertise, with colleagues working across the world to help protect people, property and the plant. Established in the UK in 2016 as a start-up business by two highly experienced fire engineering consultants, the business continues to grow at a phenomenal rate, with offices across the country in eight locations, from Edinburgh to Bath, and plans for future expansions. If you're keen to find out more or join OFR Consultants during this exciting period of growth, visit their website at ofrconsultantscom. And now back to the episode. Hello everybody, I am joined today by Esl Usten from Yulish Forging Centre, IS7. Nice to meet you.
Speaker 2:Hi, wojciech, nice to meet you as well. Thank you for the invitation.
Speaker 1:And our common guest, I guess, enrico Ronchi from Lund. Hey, enrico Hi.
Speaker 3:Wojciech, very nice to see you and hear you again and thanks again for the invitation.
Speaker 1:How are recruitments for your ERC going? Did you open some positions already?
Speaker 3:Well, you know, formally the project starts in October, but I hired the first PhD student. So I have the first one in but you know, four more people to go.
Speaker 1:I know I can imagine. That's why I'm opening the podcast. There's the biggest amount of listeners right now. If you're looking for a job in the evacuation space, Enrico, you call him.
Speaker 1:Yeah research on human crowd dynamics. A second edition of that open access document has been published. So henceforth I've invited some of the people from the very, very long list of people on the first page to talk about the document. I've reflected I have not covered the first edition of that glossary, so perhaps in this interview we can go a little bit back to the past and perhaps let's discuss, like why human crowd researchers, human crowd dynamics researchers, have sit down in one room to make a common glossary for them.
Speaker 3:I was contacted by some research at University of Eindhoven. It was Alessandro Corbet and Federico Toschi. They were aware of this Lorenz Center in the Netherlands, which is like an interesting concept because it allows to organize workshop one week long and they provide all the logistics so a venue, food, accommodations and everything for workshops of a size of about 40, 50 scientists. And then he approached me and he said you know why we don't do something multidisciplinary on the topic of psychology and physics of human crowd dynamics? And that's where we started thinking about this. Okay, we bid for this because it's on a competitive process. It was the two of them myself, armin Seyfried from Jülich was involved and also John Drury. That is a psychologist, is Ann Templeton's PhD supervisor you probably hear his name a lot if you work in evacuation because he's one of the big names in psychology there. And we got this. We won the bid and we had this event. It was one week long. It's a fantastic concept because, again, you are basically sitting in a common share space for one week. A bunch of brilliant minds I mean, I don't want to make it sound elitist, but it's kind of by invitation. So we tried to have a group of a mix of fire engineers. So I was the fire engineer there and I invited a couple of colleagues that work in fire engineering. But there were psychologists, there were physicists, there were also people working on computer science, and all with the shared interest in this topic of crowd dynamics, which is very linked to evacuation.
Speaker 3:And in this week we had planned a set of activities. First we were doing this kind of like pitch of our research because not everyone knew each other. And then, among these activities, one thing that we said you know, if you have a psychologist sitting in the same room with a physicist, it's very likely that they don't talk the same language. So we said, okay, one important thing that we need to do for the whole community is to have a shared glossary where we can understand each other, because, you know, understanding each other is the first step to be able to work together.
Speaker 3:And that's where the idea came. And during this week we had, like, some sessions entirely dedicated to having working groups that were drafting some definitions, first of all to identify what were topics that were important to cover and define, and then try to define those. And the outcome of this workshop, one of the outcomes of this workshop was actually this first edition of the glossary which, again keeping in mind that the core of the work was done in person in one week, it's quite impressive. But I mean, if you put 40, 50 researchers in a room and you give them the freedom to think, good things are going to come out of this.
Speaker 1:So it's quite an interesting concept.
Speaker 1:I can comment on your idea of this symposium. We don't do this enough in modern science. For some reason we don't have time for this in modern science. If you can reflect on that, like how often you have time to slow down, sit down with a bunch of peers and really really focus on one thing, like if you think, like 1920s nuclear physics, that's what the conferences were. You were meant to go there, show some ideas, sit down and confer, talk to each other, right? Not like today's modern rush 15 minutes, you're out of time, next one, next one, next one coffee break, dinner. Go home right and rush to your plane. Oh man, I'm jealous and I congratulate that you have first found that concept. Congratulations to Lawrence Center for organizing a venue, because modern science is really striving for things like that. And if the glossary is one of the outcomes of that meeting, then fantastic. At least we have something to chat about. And moving from that first edition to second edition, you just wanted another conference, is that?
Speaker 3:the reason no, no, no, no, no, no Maybe SL can describe that, because that came from Jülich. Then yes, exactly.
Speaker 2:So the second edition is actually also coming from not understanding each other in our department. So we were trying to conduct a research. So before we started recording, I told you guys that on my PhD I was working on motivation. And at some point in our department there is one person mostly Shrivey, but he's a computer scientist and we decided to simulate motivation, so make a pedestrian model out of it. And then we sat down, we tried to understand each other a lot and after a couple of months we realized that we have no understanding of each other at all. And during that time we were constantly checking the first glossary to be able to effectively communicate with each other. Right, but in the end we thought, okay, for example, we were talking about motivation, but motivation as a concept wasn't included in the first glossary. So we thought, okay, maybe there are also more concepts that we can think about. Then we had some internal meetings some other people in ULEs were included in the project as well and we decided, okay, maybe this should not be an inside project, but rather then we should do the second edge.
Speaker 2:Then the first thing we did, we contacted former organizers. So Enrico, I think all the former organizers apart from Federico responded yes, and so we created our organizational committee and then we talked about it. So what should we do? Should we make it a chill process without rushing, without meeting, without trying to create a workshop or something like that, make everything online or face-to-face?
Speaker 2:And in the end, we decided to do a really chill and long process without pressuring ourselves, purely online, which we can do, all of us can do as a side project, yeah, as like a side from what we are actually doing, but we can also focus on this from time to time. And, yeah, we just created the stages, like, we suggested concepts, we voted on these concepts, we created writing groups, we wrote all the concepts which are voted above the threshold, for example. And yeah, so, rather than meeting in an intense way for one week or a couple of days, I think we did it in one year, or maybe plus a couple of months of days, I think we did it in one year or maybe plus a couple of months.
Speaker 1:Well, time efficiency is another thing, but it's good to hear that projects like this can be also completed in a modern way of science, no matter how much I hate the modern way of science teams meetings and stuff like that but it's good that you can also pull something out of this modern way. A question that immediately comes to my head is what granularity of definitions you think about. Like, because you said motivation was a concept for you and that's probably some high level definition. I would say A definition of evacuation. This is the fire science show.
Speaker 1:I know the glossary is on human crowd dynamics, but the audience is definitely interested in the evacuations. Evacuation is a high-level concept. I guess how deep you go with those definitions, because eventually you have to reach a point where the definitions only make sense for this narrow group of people who are studying this particular thing and this definition will bring no value to others who are studying something completely else. So how did you decide on how big chunks to define mutually within those I don't know 40-ish scientists of different fields in the room?
Speaker 2:So the first thing, maybe I can directly say this we didn't impose that many rules on concept definitions. Okay, so what was important for us? That the writing groups should write what they feel this is appropriate for our interdisciplinary communication or understanding. And I mean while editing, since I haven't been working on all these concepts, I only worked on the concepts that we wrote in our writing group and I haven't been involved also in recall, probably, but during the editing I I read all of them intensively and, from what I'm seeing, everybody tried to focus on given a general context plus what that particular concept means in our language and, if I can add something, I mean, the only few rules that we had was that each concept should not be too long.
Speaker 3:So I think we had something like 200 words, like they couldn't have one page just on one concept. And if it was, if there were sub-concepts, then we should break it down into concept and sub-concept. The second thing we had a very long discussion on references because, you know, we didn't want this to be an exercise of people pushing for their own research or their own papers. So, if you look actually at the definitions, we don't have references in them, and that's a deliberate thing that we did because, as I said, we wanted this to be a shared common understanding rather than. You know, I am the one with more muscles and I'm going to push in what I think is the definition, because I wrote this in paper X or paper Y. So I think that's a very good starting point that we had, because then it gave a bit more peace of mind to people that okay, my definition is not going to be referenced there anyway. So then I can work together with others to find something that everyone understands and can make use of.
Speaker 3:Another aspect which is important, as I say, was the process because making a bit of a step back, not everyone wrote everything, as I said, so we had some sort of a process for splitting definitions and trying to have, you know, a reasonable workload for all of us to begin with, because first we had to you know draft concepts and then define those, refine them and then everyone will read everything. But you know, at the beginning the drafting was done in chunks by different people, different subgroups, for different concepts, and that also, you know, if you have to write five definitions, you can put a lot of time in those, rather than if you need to write you know a hundred of them, and you know that made the process much smoother because we could have you know someone that was, because we could have you know someone that was, and we also made sure that people that were involved in the definitions, but also there was at least someone that was super keen on having that, or having proposed it or voted for it to be. So we had, like, some expert in that very topic for each of the definition, along with, maybe, people that were outsiders, but they were on another field but still had to understand what was going on, because that was the challenge that we had right, because we had four main disciplines. We had physics, psychology, computer science and engineering, and so again, okay physics, social science, engineering, computer science, okay.
Speaker 3:Yes, so you know, sometimes the communication is not as easy between those fields.
Speaker 1:That's the point of making a glossary to make it.
Speaker 3:Yeah, indeed, indeed indeed.
Speaker 1:So, as I mentioned writing groups, so the definitions were split among writing. What consisted of the writing group? Was it just a group of, let's say, engineering specialists talking about engineering concepts? Or you mixed people together and put them in working groups?
Speaker 2:in each group we put all the people from all disciplines, okay, um, so what is it? The minimum was four, because we had four, let's say, discipline category. So either four people, five people or six people I don't remember the exact numbers, but in in each of them there was at least one either psychologist, sociologist, engineer, computer scientist or physicist, if I can come back to what Enrico said about also the citations and references.
Speaker 1:It's also, like you know, we kind of abuse them in this or we use them a lot in the science because of the way how scientific achievement is being tracked A lot of them, let's be fair. You said that someone could perhaps try to put a definition or cite their own work because that's going to reflect better on them in their scientific assessment. And while I believe in this, you know breadcrumbs, pathway to the original concepts and highlighting contributions of people who came before us in the world of science, I also see value, like you had 40 people in the room who are experts within their own fields and what you've created. I've picked a term from Roger Harrison from afar. He used the term community wisdom.
Speaker 1:You know, describing some ways how smoke control definitions were made in the 90s, like there was a committee and they together decided this is the best way and he referred to that as community wisdom and I think this is a really elegant term. Perhaps it needs a definition in some glossary of terms describing groups of people, but I find it very pleasant to use. You said general context and then explaining what it means. Do we have an example that would be closer to the world of fire, perhaps evacuation definitions, where you came up first with a broad definition and then had to narrow it down.
Speaker 3:If you look at, for instance, the definition of egress and egressibility, we actually decide to merge those two together and you know we first start with a very simple sentence explaining what egress is so like okay, people leaving or exit the space, which is quite intuitive to understand for everyone and then we go more in depth into explaining how this is linked to other concepts like evacuation, how it's linked to accessibility when we talk about aggressability. So, starting from something that really everyone can understand, even if they are not specifically involved in that area, and then going more in depth into the nitty-gritty details of the definition, so that even the one that is into that area could see themselves, they could be able to recognize themselves into these definitions. Because the challenge with everything that is kind of standardized in here you know I come with my experience with ISO and all the standardization groups so you want people to be able to read things and recognize themselves in those things. You don't want to have people reading some definition, reading some text, and say, oh, I would have never written it like this.
Speaker 3:So often it's better to write something more general, more agreeable in a sense, so that people don't hate it, than have something very specific that maybe a specific group will like a lot but maybe someone will hate it. So that's a bit of the challenge when you write this kind of documents that it's more important people don't hate it because they will use it than not that someone super loved a specific definition and I see this was the same in my experience because I was involved in the glossary for ISO fire safety group and it's the same thing. Sometimes people are picking on one definition because they were hating something and things will never progress. So it's much better to have things that people can agree with to some extent than have people only a portion of people loving that and another one hating it, because we need to have something that everyone uses.
Speaker 1:What level of consensus have you sought? What was it like? A unanimous decision that, yes, this is the final definition. Did you vote on them?
Speaker 3:J, yes, Ezel, maybe you can describe this because you set up this nice voting system and also consensus system.
Speaker 2:E. So I mentioned stages. We had approximately six, seven stages, and, and in each of them it contains a different consensus system. Let's say we first started with the suggesting of the concepts that we want to see in the second edition and we had a huge list right Like maybe 150 different concepts.
Speaker 1:Sorry, by word concept you mean a kind of a definition that's in the glossary, because you're using that Just a word. Yeah, a concept of a definition that's in the glossary because you're using that Just a word. Yeah, a concept is a word, and then it gets a definition in the glossary. So, yeah, okay, that's okay.
Speaker 2:I started from the beginning. Actually, that's fair, yeah. So everybody suggested we created a sort of like a website and it was like just type your concept and hit enter, that's it. And then we collected all these, we grouped them and then we sent to everyone every single router and said, like, vote on them, which one would you like to see more? And then we had basically a quantity of the weights of these concepts and then we saw, okay, like, for example, flow, flow rate, this had, I don't know, 50 volts Out of 65 routers. 50 volts, it's amazing. Okay, we took all that. So we set a threshold. Above the threshold, we took all the concepts.
Speaker 2:Then we distributed all these concepts to these writing groups which we randomly selected. It wasn't that random because we want to book everyone from each discipline to these groups. So each group had three, four concepts. Let's say they wrote these concepts even though in that group, for example, they have a concept but they are not the expert on that concept. Still, we wanted them to write this and then they wrote it. We called these draft definition drafts and then we posted in a shared folder and we said to everyone okay, now it's time to review and you have unlimited rights, review anything that you want. Then our shared folder became a crazy, a monster. In the end it was really like maybe 10, 15 seconds you needed to wait to open the file. It was crazy, like it was really big. All these comments, all these reviews and in the end the reviews were actually cumulative reviews, so everybody was seeing the review of the person who did it previously and they were like cumulatively getting reviewed. And the last review we took it as the final definition.
Speaker 1:Okay, I also had a question about because it's called Glossary for Research. So was it immediately thought as a tool for researchers, scientists, or also engineers, practitioners, or that's a byproduct and you just focus on?
Speaker 3:researchers. I'm an engineer, so I see value of this kind of tool also for engineers because, at the end of the day, there are many concepts that are unclear. If you look, for instance, at our fire engineering field, there is still a lot of misconceptions and terms that are not clearly defined. But I think an important thing is that we wanted to give this kind of meaning of research, in a sense that we say, okay, this is not just a bunch of friends deciding on something, this is a bunch of scientists. Let's say that they're supposed to know what they're doing. So to give more credibility of it, I think to to have the keyword research has been important because, again, an engineer will probably cite something that comes from research.
Speaker 3:Sometimes researchers are more would probably cite something that comes from research. Sometimes researchers are more skeptical in citing something that comes from engineering. So in a way it's a. Again, we were writing a glossary, so words are very important, but it's a way to push for credibility, keeping in mind that not everyone was necessarily only a scientist, because we had also in the first edition, some people that were more from the practice world, for instance, of crowd dynamics, you know, people involved in crowd management, on crowd events and so on, but most people are actually scientists. I mean, if you look at the list, I think pretty much almost everyone has a PhD in there. So I think the word research is important because it sends this clear message that this is a tool developed by scientists and, of course, engineers will find this useful, especially in our world of fire safety engineering Because, again, we touched on a lot of topics for which still, if you go around and ask around, I'm pretty sure there is a lot of misconceptions.
Speaker 1:If you would narrow this discussion to concepts relevant to fire evacuation, were there many of those concepts that other groups of researchers in the room would completely differently understand than the fire researchers?
Speaker 3:Well, you know, statistically, if you have 60 plus authors, there would be one or two that disagree on something.
Speaker 1:Different opinion.
Speaker 3:And I mean there are some concepts which have been very much debated, I mean panic, crowd, crush, stampede, just to mention a few, even fundamental diagrams.
Speaker 3:You know, I was the one starting questioning some of the definition that we had of fundamental diagram, because there is this never-ending discussion into how fundamental should something be to be called fundamental, because we can find many fundamental diagrams if you look at children, adults, people with disabilities and so on.
Speaker 3:But I mean the nice feeling was, though, that everyone was with a positive attitude, so everyone had the mindset that we are doing something for the good of our community. I mean, there were no money involved in this, as I say, while for the first edition at least, we had the workshop paid, let's say, by this Lawrence Center, we had all the facility and all the venue paid, so it was also a nice excuse to meet with a couple of friends there, but this was all on a volunteer basis. So we, the whole effort was to try to build also a positive community sense. So we're doing something for free, we're doing something on a volunteer basis and we're doing this for the good of the whole community. So we never really experienced someone like having a negative attitude or like, let's say say, being stuck on a topic. Actually, even the conflicts that we had in terms of definition, there were very few and we were solved pretty smoothly.
Speaker 2:I don't recall, ezel, maybe you remember how many there were, but we talk about five, six terms that had not too many right, I mean originally we were thinking, we thought we are going to have many conflicts and we were thinking, okay, we need to arrange a meeting among all the organizers and in the end we had, like what you said, five, six, which we can actually solve them through mailing. We didn't even have to meet. It was really interesting.
Speaker 1:Perhaps the human crowd dynamics? Researchers are more civilized than the rest of us. Teach us.
Speaker 3:I would be interested. I mean to be honest with you. This is an exercise that every community should do. I would love to have a fire safety engineering glossary, but again there would be a challenge to have 65 plus people.
Speaker 1:Which is kind of interesting because you know, in fire you would have modelers, you would have experimentalists, you would have practitioners, you would have academics, each of them having perhaps a different view on even the simplest things like what constitutes a fire.
Speaker 1:Like that's a definition, you could battle for a while and I assume it could be as similar as constituting the definition for evacuation, definition for evacuation.
Speaker 1:But what you previously said about the definitions, that rather are, you know, not excluding anyone that you find a piece of yourself in the definition and you sacrifice perhaps some of the stuff you would like in a definition for it to be more broadly representative to others, and then again you can build on the definition. It's not that this is it. It's not that evacuation is only this one page in your glossary. It's not that this is it. It's not that evacuation is only this one page in your glossary, it's much more. But that's a common starting point and if you approach a crowd psychologist, someone who's modeling evacuation, a computer scientist or evacuation specialist, this is something that opens the doors. I guess we're capable of enhancing our FIRE definitions through the wisdom of the other groups as well. I wonder, like if you were going with the definition of, let's say, evacuation, like how much of that definition is what the FIRE people wrote and started with and how much did it evolve during the discussion?
Speaker 3:I have to say that's one of the least controversial definitions because at the end of the day we decided to split it in sub definitions which looked at different aspects of it. So you know, we looked at face evacuation, self evacuation, community evacuation, assist evacuation. So we kind of split it in sub parts and again, with this period of having everyone be able to recognize themselves into that definition, so maybe some parts of it will probably be more specific because, for instance, if we look at, one of the sub-definitions was controlled evacuation, which is probably something that you use a lot in crowd management and management of events, much less in a fire, for instance. But I mean you still have things like phased evacuation or assisted evacuation, which are very typical of a fire, for instance, but I mean you still have things like face evacuation or assist evacuation, which are very typical of a fire scenario.
Speaker 3:So again, the spirit was this, and I can make a nice parallelism I mean, the way I see writing a glossary is like being married, so the best is to find compromises. The things that function are the ones that are in the middle. I mean, if someone wants to be stuck in their position, things will not move forward. So in order to not have a divorce in a glossary, you need to compromise and find something that is making everyone happy in the middle.
Speaker 2:Most of the time, I would agree. Yeah, compromises, but we also did something also. What is it like a special version of this compromise? In some definitions we also added the disagreeing definitions, the disagreeing parts as well.
Speaker 3:We had situations in which, indeed, we had like contrasting definitions in a way, and we wanted to still bring those forward. That's a bit the idea like contrasting definitions in a way, and we wanted to still bring those forward. That's a bit the idea, but maybe, hazar, you can bring some examples.
Speaker 2:The biggest example, I'd say, would be fundamental there.
Speaker 3:I remember, for instance, in that definition, that I was the one saying okay, we need to state very clearly and explicitly not everyone likes the idea of fundamental ground.
Speaker 3:As I say, I'm one of those that use that because everyone uses it, but I'm not super fond of it.
Speaker 3:But we wrote something like okay, keep in mind that even if we use this concept, still we need to be aware that because of multiple reasons demographics, cultural differences and so on we need to be aware that there may be different fundamental curves that relate to density, speed and flows.
Speaker 3:So this kind of idea of not just saying this is what it is, but also give a bit of reasoning of what is behind what the field recognizes and acknowledges from both sides, I think is really helpful because it really helps reflect the whole picture of the field. And again, that's actually as good that you brought this forward, because that's one of those, let's say, conflicts that we had in terms of definition, that we had to work more when we are drafting the revised version, because this was not a new definition, this was a revised definition. I recall, indeed we had the first definition and indeed the process of doing the second glossary was also to get feedback from the community and get feedback from different people and hear the sense of the community, because these are kind of living documents. They're meant to be living documents. We don't want this to be the final version. That's the whole idea.
Speaker 1:Yep, I mean for my listeners. I would highly recommend its open access. So you just open it. It's 32 pages. It's not overfilled with additional content, it just gets you straight into the definitions and the glossary. That's the point of having a glossary Plus it gives some additional information at the end about how the glossary was made, which we're covering in this discussion as well. So I highly actually recommend going through the glossary and eyeballing it, at least checking out the relevant definitions and see if you understand them in the same way.
Speaker 1:Or perhaps is there something else. Maybe you could try to do an exercise and actually go through some of those concepts and definitions and you can give me a condensed version, because some of them are actually longer, and discuss how important it was for the general field of human crowd dynamics, how important it is for fire people. The glossary is arranged in an alphabetical order. I'm not sure if you're talking in alphabetical would be the best. Perhaps let's start with something we already touched the fundamental diagrams and then we'll move on to some other concepts. So, enrico, you claim to be the biggest fan of fundamental diagrams, so take this one.
Speaker 3:No, but I mean this is, for instance. I have to say there is a history behind this, because this is a concept which is very widely used, for instance, in the world of physics and also in the world of traffic engineering. You know, by education I'm a traffic engineer, so the first time I actually heard about fundamental diagrams was not when I was looking at location and pedestrian dynamic, but it was earlier in my education when I was looking at traffic flows. And again, this idea of having a general understanding of how to relate these properties of movement can be cars, it can be people. In our case, it's actually very useful. Movement. It can be cars, it can be people. In our case, it's actually very useful.
Speaker 3:And I understand that if you work in the physics field, you want fundamental properties, you want fundamental relationship. It's something that you're really used to. The laws of physics is not something that you're used to question. It's something that you know. It's how it is. And I mean for your listeners that are in the fire modeling or fire science or, more specific, in fire dynamics, that's how it is.
Speaker 1:You're not gonna go there and start questioning the laws of physics the speed of light is not an opinion, it's a constant right, and if something in physics is a fundamental diagram, it's just a relationship, how these things change, based on a sound theory, and here it's kind of observation experiments, right.
Speaker 3:And that's the thing, because the idea of this comes from experimental data and then it's been widely used in modeling to try to have some sort of relationship that can represent how people move. But reality is that the more we go on, the more we discover that there is so much nuances in what we call fundamental diagrams, in terms that if we change some of the boundary conditions, so if we change the population, if we change the setup where we are doing experiments, if we change the culture of people you know, we have seen this with COVID, like people keeping different distances depending on where they come from, and so on and so on, all these kinds of properties in which we have more and more data, fortunately, can affect those relationships. And that's why, again, when we put together this definition, it was important to acknowledge that there are factors that can make what we call this fundamental diagram not necessarily valid for everything, but we need to actually acknowledge that there is not one fundamental relationship for everything. So, but again, here it comes, the negotiation and the compromise, because I totally understand you know, I work together with, with physicists very often and it's a completely different mindset and again, going on the opposite end of this, of the of the picture.
Speaker 3:When you have a psychologist which I guess they are trained from day one as they're correcting critical thinking you question everything around you, right? So nothing is fundamental, almost. So it's kind of important to acknowledge these two sides and go a bit in the middle. Sometimes as engineers I feel like we are in the middle, so we are kind of close to the physical sciences, the hard sciences, in a way that we have to trust center fundamental properties. But on the other hand we are super exposed as well from all these concepts that come from human behavior when we work, especially in evacuation. So we kind of have this role of trying to compromise things. But again, I see this as a good example to exemplify the challenges that you have when you want to put together this type of documents.
Speaker 1:Hearing you speak about the process and the challenges within the process it makes me appreciate the definition even more, because now, looking at the definition, it really reflects what you said. It says the fundamental diagram describes the transport properties of crowds by illustrating the relationship between density, speed and flow. Yes, we know that fundamental diagram is essentially that. The definition is much longer than that, but in the end it ends with imposing an empirical curve on a model. Without considering demographic, procedural, geometric or cultural differences may lead to misleading or inappropriate conclusions. That's, in the essence, the consensus that you have maintained to build on this difficult definition and all together, this is very useful. If someone is about to start a PhD and they need to refer to the fundamental diagrams and they reach to your glossary, they will have a good starting point in there.
Speaker 3:And I mean, if we think about file engineering, you know we often see these curves. You know in the SFP handbook and so on. And if you're new to this, if you don't know everything that is behind these curves that relate to, for instance, speed and density or flow and density, you just take them for granted. But it's important to be aware of these kinds of definitions because that makes you understand that it's not the same as the speed of light. You know it's. There may be parts in the, in the documents that we're used to read, which is what it is. Instead, those kind of curves. There are a whole set of assumptions behind.
Speaker 3:Many people even don't understand that often they are design curves in fire engineering. They're not necessarily empirical. So you start from empirical curves but then you make them more conservative and then you see a lot of papers that start questioning oh my experimental data don't match with the equations that I see in the SFPM. Of course those are conservative, they're meant for design. They're not necessarily matching empirical data. They are based on empirical data but they have a different scope. But this is the kind of discussion that we want to open with this kind of definitions.
Speaker 1:What about the terms that are? Let's say, I would expect them to be easy to define, Like there's two next to each other, density and distance, Like both feel like something very obvious to define. But actually the definitions in the book are quite nuanced and I see our computer science colleagues in those definitions a lot. And that's very interesting because indeed in relationship to fundamental diagram, like density is your input and you read out the flow rate. But if you're a computer scientist and you have to solve a discrete model, that is quite a big, big challenge. So let's try to tackle those two definitions, if we can.
Speaker 3:For density. You know the story behind this is that you probably know that there are too many ways of calling density. You know the classic thing is people per square meter, which is what we often use in fire engineering. But you know it's not the only way of doing this and there is a lot of way to actually calculate densities that come from the world of computer science or physics and so on, which look at other things. I mean the very famous one is the one from Predachinsky and Milinsky. You probably are aware of this Vojtech that you know in Russia they were doing in the 70s, 80s.
Speaker 3:This alternative method is the one that is very popular in fire engineering, where you actually use the ratio between areas so that it's kind of able to, for instance, factor in different body sizes, which is something that you cannot do directly. If you use the classic equations that you have in the SFP handbook, for instance. And you know the computer scientists, the physicists, they use all sorts of methods. I mean the group in Ehrlich, some of your colleagues, for instance. They were the ones among the first ones bringing in the concept of Voronoi, the composition, into a calculation of density.
Speaker 3:I'm not going to go into the details of this, but the idea is to basically check, study density, calculating distances between people to some extent, and this may sound more complex, but again, for a person that comes from psychology that's a good thing, for instance for someone like Zeld.
Speaker 3:I mean, you're not necessarily into the details, I guess, of different ways of calculated density that are happening in physics you still appreciate, with a document like this, the fact that you are aware now of the existence of different methods to even call density, what we call density, and that's an important step, because otherwise we just the alternative was just to say, okay, people per square meter, that's it. But then someone will not recognize themselves into that Because, as I said, I've seen a bunch of papers and reviewed a bunch of documents which define density in very different ways. Even if we look at fire safety codes, sometimes you know they talk about the area per people, not people per area, or they look at other concepts. So, as I said, it's important to bring this kind of other alternative definitions into the glossary so that everyone can recognize into that from my perspective, I agree with everything that you say, enrico.
Speaker 2:Firstly, uh, but like in terms of density, for example, and my main motivation would be the effects of density right, the psychological effects, but at the same time, I wasn't aware that density or distance, as a matter of fact, contains this rich history or definition of conversation behind it. So now I learned it, but I mean, during my PhD and then postdoc, I also learned all these things and I don't know effectively conduct researchers on that as well. But, for example, now we have a new psychology PhD on that as well. But, for example, now we have a new psychology PhD and, for example, she's coming from a really different area, neuropsychology. She doesn't know any concepts that we are using. She knows the general definition of density or distance, but she doesn't. She wasn't aware of our context in the end, and the first thing we did we just showed the glossary and it was brilliant. Then we just talked about it.
Speaker 1:It kind of works. I mean, even here we discovered the richness of the definition inside a term that you would feel it's very simple as density, and in the same way, the computer scientists could perhaps find simplicity in some terms that we use I don't know panic, and they would discover the richness within that term. Maybe let's talk some closer to yours, Ezel. You studied motivation. How did motivation end up in the glossary and are you happy with the definition? Do you see yourself in the definition?
Speaker 2:To be honest, I haven't worked on motivation at all. I am really. I mean, in the end it was like a lottery, right, Motivation didn't fall on me, Okay, but it was okay. I tried to review it. Then I realized that it doesn't need any further reviewing at all because whoever did it made a brilliant joke and I think for that definition we had only one or two really minor reviews, like adding one sentence or like changing one word or something like it, and from my point of view it was brilliant. It's drastic.
Speaker 1:How about response time? Because I also feel that this would have a very strong connotation with FHIR and perhaps it could be understood differently in different groups of code experts.
Speaker 3:And perhaps it could be understood differently in different groups of cloud experts. And I will say it's pretty different when it comes to what we have in fire engineering, what we have in human cryodynamics, because often response time, when we look into crowd dynamics, is referred to the immediate response in a sense. So how do you respond, for instance, in a situation like collision avoidance, like someone in counter flow going against each other, or if you are changing your trajectory because you have someone moving next to you or overtaking? So, as I said, this is something that it's important again for someone like me that, for instance, I don't necessarily use that constant, that in that way, because often for me, response time as a fire engineer, you use it as a synonym of delay time or pre-vacation time instead, in this specific field, as another meeting meaning which is quite important to be aware of. Because again, here comes the. If I'm sitting on a table with someone that comes from computer science and is trying to model counterflows and talks about response time, I will sit there and say what are you talking about?
Speaker 3:Response time, counterflow, response time no, this has nothing to do. Why? Because it can happen that we use the same wording for different concepts. And that's again when a glossary helps you because, again, you don't have to be necessarily aware of everything that is used in different fields, but in this way, you know, we can have an agreed way of using a given definition. And again, that's meant to be helpful both for people that are new to the field but also for people that are in the field but are not necessarily familiar with how that concept is used in that specific application. That is, human crowd dynamics. Because, as I said, very often in fire engineering, when we talk about response time we do talk about something else.
Speaker 1:Yeah, another interesting to me is that there's a term behavior. It has a very general definition and then there are like nine different sub-definitions of different things. That looks like a fun one. So how did you come up with the definition and the challenges related to that and usefulness of the term behavior in terms of FHIR perhaps?
Speaker 2:I think this is one of the emerged concepts. So I mentioned the first thing that we did. We suggested new concepts, right, or revisions of the old concepts, and there were, like many different behavior related suggestions, and what we did was we just checked whether it makes sense to merge and in the end we maybe 90, yeah, almost 90% of it we merged. And then we had this structure, a concept which is the umbrella concept, then the sub-concepts, and then we just distributed these concepts to the writing groups and I can imagine and if I remember correctly, it is as it is the definitions, because they are not coming from the same working groups. They are a little bit different from each other, but in the end they fit quite well, even though coming from different minds.
Speaker 1:I find those definitions a little interesting. I wanted to end by asking about how did you finish the definition for the panic, for the P word? But I also see there's a non-rational behavior definition, there's irrational behavioral definition, so it's very interesting. Can you tell me about the concept of panic and how it was defined in the glossary and the consensus? How did it look like? And then maybe we can talk about the rational, non-rational behaviors as well, why there's the distinction.
Speaker 3:I can give a bit of history on this, because we had a very long discussion when we had the workshop in Leiden and the Lawrence Center about having or not having words that are, let's say, misused or misunderstood in the field. Because at the beginning we were thinking, okay, let's not have these words, otherwise people will just start using them even more. But then we thought, okay, there is the risk that if something is unclear because it's not defined, it will be even more often misused. So it's better to have something and advice very specifically on what it is and what is not, in a way that people can be hopefully more aware of the misuse of those, of those wording. And you know, panic is the typical example where we still see a lot of people unfortunately even you know in the field that use this word in the wrong way. Especially media is still very often used.
Speaker 3:But I mean the idea there was to try to clarify what are the boundaries of what panic is, in a way that people could have a clear, let's say, understanding on where to not use it. Because, for instance, in a part we say the term is often used as a vague catch-all for all range of phenomena. So we say this explicitly. You know people use this for everything, while it's not the way it should be used, so we say this explicitly. You know people use this for everything, while it's not the way it should be used, so we've been very explicit on this. So the idea is that, rather than hiding behind the knowledge that we wrote this have, is to try to be very explicit also on what are common mistakes and what are common misunderstanding in this kind of words. We did the same with Stampede. We had also the wording of Stampede, which is another controversial term. I don't know, ezel, how do you see this from the perspective of social science, but I guess that's another field in which this is very much debated.
Speaker 2:Right, it is, it is highly debated, but I think we did a good job Of panic as a concept in the glossary. I mean, there weren't any conflict regarding panic, because maybe I can also talk about the evaluation of some of the concepts. Right, not evaluation, sorry, evolution. The panic firstly started as a part of a suggestion of blacklisted concepts. So panic stampede no, stampede wasn't in it but, like all the controversial concepts, were inside of it. And then we were discussing whether we actually define or not define or define the whole blacklisted concepts as why they are getting blacklisted the relation with media, the relation with misuse and everything and then we decided to actually create individual concepts for each of them and effectively explain everything in all the angles that we can cover.
Speaker 2:So this was the, let's say, evolution of the panic. For example, response time. It also contains a history as well. I think it started with a merge of three different concepts response time, reaction time and something else and so the definition should have been the grand definition of all these three concepts. Or, for example, flow. It was just flow at the beginning, but during the discussions we decided to have an extra sub-concept, which is flow rate, and in the end it merged, or rather it divided to two different concepts.
Speaker 1:I also like that you have definitions of things like experiment model. I think it's actually quite nice to have sound definitions of those concepts among researchers. I think we're narrowing down to the end of the interview to have a sound definitions of those concepts among researchers. I think we're narrowing down to the end of the interview, so unless there's a term that you're dying to talk about, we can wrap on, or maybe we can take one more.
Speaker 3:Well, I want to just bring up that, for instance, even very simple concepts require a lot of thinking if you are in the field, like I mean, distance we talked about, we mentioned about, we mentioned it before.
Speaker 3:I mean distance, how difficult can be distance? Well, if you work on a grid, it's not so easy to define this. It's not as easy, let's say. But even velocity, I mean, if you, that's another area in which there is a lot of misuse and misunderstanding. You know, I teach this kind of stuff with the vacation simulations to fire engineers and there is you know, it's classic exam questions and I see people misunderstanding the concept of desire, velocity, observe velocity. So to have this kind of some concepts that explain how even a very simple concept, which is something that you learn probably in primary school, almost velocity, can have many nuances, I think it's actually useful. Because that's another thing that often can happen People may, especially if they are not in the field, or they approach this field in a tangential way, they may think they know.
Speaker 3:And that's the worst, because if I hear a word that I never heard of and I'm not familiar with, yes, maybe I'm keen in going into the glossary and search for it. Okay, I hear the word in behavioral repertoire. Well, I've never heard of this, probably, so I'm going to go and read about it. But if I hear velocity, oh, I know what velocity is and I don't need someone to explain me what is velocity. Well, in this specific world, if we talk about desired velocity, if you talk about observed velocity, if you talk about free velocity, these are all nuanced definitions that need an explanation because they make a lot of a difference, potentially, if you don't understand what you're talking about, right? So the concept of desired velocity and how this is linked to motivation, indeed, and the speed that people would like to go, but they cannot go because they're actually interacting with space or they're interacting with other people. So I think this is an important step and that's why I think, if you're working in this field, you should have a whole read through, not thinking, okay, I'm going to just jump into the things that I know, that I don't know, because maybe I read some keywords that I never heard of, but actually, I really advise people to spend some time and reading the whole document, because it can give a lot of nuances, a lot of details that you may overlook and say, okay, now that I read it, I understand it and I think I have my mind more clear on what this means, but without having those kind of definitions very clear, it's very possible, and it's very often, that people misunderstand concepts, and I mean imagine doing a design and misunderstanding an actual velocity for a desired velocity. I mean you may be completely misunderstanding what a vacation time might have in a building. So that's what I'm saying in terms of doing this kind of exercise being very useful for the whole community and that's why I would advise any community to do something like this.
Speaker 3:I mean I really wish, I mean we have, you know, we have something like this in fire engineering because we have a nice document with the glossary and terminology, but it's not the same thing. I will say that something that is driven purely by scientists and has that kind of drive by scientists, with that kind of mindset, that is defined and used for research, is slightly different than something that comes from some somewhere like ISO, where there is a lot of practitioners, industry, when maybe they're more interested, I would say, sometimes in defining things more clearly, with more narrow definitions, because you know, iso has to be clear, they have to be standard. So there is no space, no room for interpretation. It needs to be 100% obvious what you're saying and there is no room for saying, okay, you cannot use this in this way, or there is a history behind this word, because that's not what the purpose of ISO is. So I really wish, for instance, that at some point someone will bid to this Lawrence Center and have a full week with a bunch of fire scientists.
Speaker 3:Was the food good? Well, the food was okay. I mean, it was not Italian.
Speaker 2:Was the food good? Well, the food was okay. I mean you know, it was not
Speaker 3:Italian, but you know, you touch a very sensitive topic here.
Speaker 1:I know I should have wondered Don't go that path, don't go that path.
Speaker 3:But I mean Don't go that path, but even the simple fact of having a conference where all the logistics are ready, you have rooms, you have space for workshops, space for lectures, space for everything and I have a bunch of scientists sitting in the same office in the same space without having the destruction of laptops answering emails. You know you had a workshop, everyone had a task, so you couldn't get distracted. You know, go and answer some emails or pick your phones and do all their stuff. No, everyone had a task. So in that kind of setup, really get a lot of stuff done in a very short time. So I really wish at some point someone will do something like this, which is unfortunately very uncommon In our field. I don't think I've seen things like this. We have summer schools In general in science. Don't think I've seen things like this. You know we have summer schools.
Speaker 1:In general in science, Enrico, in general in science, I would say this is extremely uncommon. You don't have time for that. People don't have time to do science. We do so much administrative bullshit around our life of a scientist, you don't really have time. And this is how you do science. No-transcript. And it always fascinated me how those researchers, when they had a problem to solve, they would go for like a six-hour in the los alamos mountains around you know los alamos and then they would just discuss and talk and then they would come up with answer. We don't do that today. Like the best you can do is write an email which still gets the job done, as as shown in the revision. But I'm jealous of being able to to be fully connected to this type of work.
Speaker 3:But especially, you know organizations like, again, large organizations like FSS or SFPE. I mean, I know now you're a big boss of SFPE Europe, so you're the right person to talk to. But you know, for instance, to have a concept like this would be nice to have like, okay, we take three days. It's not a conference, it's not someone listening, it's someone that meet in a place for a task. So there needs to be a goal, otherwise it becomes just a chat among friends and they cannot go that way.
Speaker 3:But if you have a concrete goal, like a glossary or drafting an agenda for a research agenda or a white paper on a given subtopic, that's actually really effective. I mean because, again, picking up the brain of these smart people that we have in all our communities because we have a bunch of very smart people in our communities you don't need necessarily a full week, but having two, three days in which you know you pick different expertise. There needs to be that element of multidisciplinary, that element of different perspective. There cannot be everyone coming from the same field, otherwise really becomes a bunch of friends deciding on their own. It needs to collect different perspective. But that would be really nice. I'm just launching you an idea, wojciech for something for us. Wojciech Białysiak, yeah, yeah.
Speaker 1:We're cooking something like that, maybe not on such a grand scale, but perhaps it should be on such a grand scale. I'll definitely work with that as well. How was the experience for you as a PhD student tackling with their own you know definition problems? Have you found answers in this group? Was it fulfilling to do this revision of the glossary?
Speaker 2:No, no, no, absolutely. I mean I learned a lot during my time in either organizing or either participating. No, I mean I learned a lot during my time in either organizing or either participating. No, I mean it was really amazing Like we learned many things. Otherwise I would probably not learn or just hear or not think about it that much, so I don't know it was really amazing.
Speaker 1:In the end, did you find a common understanding of motivation with your computer science colleague.
Speaker 2:I mean, we are about to finish that paper. Hopefully this year we are going to submit it.
Speaker 1:Let's see.
Speaker 2:I mean, the model is there. Now we know what we are talking about. We have understood the motivation and how we can computerize it.
Speaker 1:And now, as the glossary is published and you get a nasty comment from a reviewer that it's something else, you can refer them to the glossary. No, no, the collective wisdom of of a crowd behavior peep said otherwise that that's. That's also a useful, useful thing. Um guys, thank you so much for coming. The document is in open access. The links are in the show notes. We highly recommend everyone to go through it. See if you recognize yourself in the definition. See if there's something you understood differently. See if you recognize yourself in the definition. See if there's something you understood differently. See if we're all on the same page of those important concepts. And, of course, human aspect, evacuation, crowd dynamics, important part of fire science. So we really should all be on the same page in here. Thanks guys for joining me in the Fire.
Speaker 3:Science Show. Thanks, wojciech. Thanks again for the invitation.
Speaker 1:Yeah, thank you, wojciech. It was really nice and that's it. I'm not even sure how to summarize it. I guess I'll go into the theme of giving back. A lot of people would like to give back to the community. I think many of us feel blessed for working in fire safety engineering. In some odd, twisted way, I would say 90% of people I meet along my pathway came to fire safety engineering or fire safety science by accident or by some odd circumstance, you know, at random. It's not that entire childhood you've planned. You will be investigating turbulent combustion and I think we found our way through this and it seems we all love it.
Speaker 1:And, yeah, it's a great community of people. It's a very, very tiny community. It's a very small community that tackles one of the hardest scientific problems of the modern world. Therefore, it's a community in which any effort to give back, to build something, to help someone else, is extremely welcome. And what you've seen in this podcast episode is not just a glossary for evacuation. Of course, that's very important. That's why I brought those guys into the podcast. We've talked about it.
Speaker 1:It's great that they've built this resource, and the resource itself is amazing, but they also give you a blueprint on how to arrange something that doesn't look like that much work. I mean, they finished the first one in a week-long meeting and Dazzle managed to get an update, a big update, through remote work, without any meeting at all. So it's a manageable effort. Yet it gave community something very, very useful, and I would like to thank again the organizers of this project. It's an amazing work and I really hope stuff like that pops out in different spaces of fire safety engineering. So that's it for today's Fire Science Show episode. Thank you for being here with me, and if you're looking for some fire science, you'll find it. Next Wednesday, same time, same place. See you there. It next Wednesday, same time, same place. See you there. Cheers, bye.