#82 Milena Nikolic, CTO at Trainline: Transforming Transportation Technology

0:00I have now been in the tech industry that unfortunately has fairly poor representation, possibly worse than many other ones. I have seen the change over the last 10-15 years. The percentages have moved and they have moved by modest amount, like I'm talking single digit, 1 % or 2%. However, it is an improvement. And what has certainly moved more than the numbers themselves is the discourse and the narrative and people's understanding of why this matters and what we need to do to fix it. So I'm cautiously hopeful.

0:40Now and then, we get a guest on to the Tech Leaders Podcast that we like to shout from the rooftops and tell everybody about. This is definitely one of those moments. Milena Nikolic is the CTO of Trainline.com. As a young lady growing up in Serbia, Milena was always attracted to a career in technology. So when an opportunity arose to join Google, who were a powerhouse then, let alone now, and also to join Google in London. This was back in 2008. Milena jumped at the chance. Fast forward 15 years, she is now the CTO of travel aggregator giant, trainline.com, one of the most recognized tech company brands, certainly in Britain, if not in Europe.

1:30We covered everything from the recipe to successful delegation through to the HS2 debacle, what it really means to be a chief technology officer, a female representation in the boardroom, something that Milena is very passionate about, and much, much more. A lovely lady, fantastic interview, so driven, so knowledgeable. This is what the Tech Leaders podcast is all about. I hope you enjoy it. It's Milena Nikolic.

2:06Milena, thank you so much for coming on the Tech Leaders Podcast. I've been in excited anticipation of this day, and I've been really, really, really looking forward to talking to you. The CTO of TrainLine.com. How are you today in London? I'm having your garden done by the sounds of it, yeah? Yes, I am. And thank you, Garrett, for inviting me. Very, very happy to be here. Looking forward to the conversation. Yeah, fantastic. So much to talk about. Trainline.com, are you sort of a two, three split now? Do you work from home every Friday? What have you guys implemented post-COVID in terms of remote office split?

2:42We have actually just announced this to the team a couple of weeks ago. We are doing an approach we're calling Flexi First, which is 40 % over 12 weeks. We expect people to be in the office. So it's not quite two days a week. It's kind of more average approach. We are really very excited to be still banking on the flexibility that we were all getting from work from home. However, we also want to be spending some more time together, which is very important. So that is our approach of 40 % over 12 weeks. Wow, that's very specific. No, I like that. Most organizations that I'm aware of are either totally remote, totally back in the office, or a 2-3 or 3-2 split.

3:21So that's refreshing. I think organizations will become more mature in terms of how they do this going forward, doesn't they? but it sounds like you guys are ahead of the game. So congratulations on that. But let's start with the question we always start with. Really looking forward to asking you this one, actually. What does good leadership mean to you, Milena? I would say leadership has to be with a purpose, you know, in the aim of something. So I think that's one of the key things. So just kind of driving towards a goal, you know, having an opinion, having a vision. So I think that's very key.

3:58And then certainly efficiency is a point that comes to it, kind of like reaching the goal in a way that's optimal and efficient. And then finally, with, you know, taking others on the journey. So sort of taking the people and the team aspect in mind. So when I think about leadership, I always think about the kind of the purpose, the vision, the kind of having something to stand for, you know, getting there in the most optimal and efficient way and taking the team journey with you. Yeah, fantastic answer. I think I completely agree with that. It's about setting that clear purpose and aligning a team towards that purpose.

4:35There's an art to that, isn't it? It's a difficult thing to do well. You've obviously done a very good job. You spent 12 years at Google, ended up in a very senior leadership position. So can you tell us a little bit about how you come to work for Google? I know you joined in 2008, is that correct? As a software engineer, and you quickly went up the ranks and ended as an engineering director. Talk us through that experience, how you joined Google and what you learned from working for that organization. So I joined Google as an intern while I was still at the university just for kind of a summer internship program and kind of, I guess, did okay in that internship.

5:10So they offered me a new grad full-time job once I graduated. And that's when I moved to London. I started as a new grad software engineer and did that over many years over many Google products. So I've done some work on Google search. I've done plenty of infrastructural work that eventually translated into Google Cloud. And then for many years, I was on Android and Google Play. Absolutely loved writing code. I love designing systems. I loved everything about being an engineer and engineer at various different levels from junior, mid-senior, or kind of all the way up to staff. And was never particularly attracted to moving into some sort of leadership position until Google reached the stage where it was growing very fast.

5:54So a lot of people were joining and I started to realize that the hard problems we're dealing with are actually people problems and not technology problems at that stage. That was a time when I decided to give kind of management a go and just see how it goes. And sort of to my own surprise, I ended up liking it. I liked getting more from the teams than, you know, they would have if I weren't there. I love them land impact and kind of make a difference in a meaningful way. And of course, I love building people, helping them grow their career and more than anything, building teams into kind of coherent and productive units in that sense.

6:31So kind of then stayed in leadership roles the rest of my career. I was engineering manager, then senior engineer manager, and then eventually director and senior director at Google. And then, yeah, kind of that's the that sort of so yeah, building productive tech organizations is kind of what I see as my, you know, job and mission and purpose. If you were to sort of reflecting back on your time with Google now, what were the biggest lessons you learned there? Do you think that you've taken into your role with trainline.com? So engineering culture and the culture needed to build products and kind of to make a meaningful difference with technology is probably kind of the biggest one thing.

7:11if I have to single something out. I don't take the world culture easily because I think it's being thrown around as one of those, you know, just glue words that very often doesn't actually have a lot of backing. But for me, there is the sort of fine line between, you know, how different functions within software development teams interact and operate and who's accountable for what and who's responsible. And how do you incentivize everyone in that group to really want to do the right thing for the business kind of through technology, to work on the right thing, to work in the most efficient way.

7:46So I think some of those core aspects of organizing work and incentivizing people to care about the right things, be that the quality of the software that they make, the quality of the product that they build, the metrics that are trying to drive, kind of all of those aspects. I think that that was probably one of the biggest lessons. And it's not to be taken for granted. I think in a lot of more, well maybe not so digitally native tech organizations very often tech teams are treated as an implementation arm of the business so kind of just someone you you know code monkeys that you throw the the problem back to just to kind of to build it out and i'm a big believer in kind of tech teams needing to have an opinion and needing to be part of deciding what's being done rather than just implementing it as well as you know driving innovation and kind of all of that good stuff.

8:35Yeah, absolutely. So looking back now, then what would you change about your time with Google? Oh, dear. Good question. I had very many years where I, you know, work hard, which have no regrets about would not change that. Like I think, you know, we all have fears in our career when we work very hard. And then when we figure out ways to work smart and kind of all that, the bit that I would change is that I was kind of, I didn't really trust the system and the journey. and I was just getting very frustrated with quite a lot of things. And, you know, I'm generally an opinionated person. So kind of like I would see something and be like, that's not right.

9:10And that's not what we should be investing in. And this is not how we should be building things. And I think my heart was always in the right place. And I think I quite often actually had a point with what I was trying to say. Not always, but quite often I had a point with what I was trying to say and drive. But I shouldn't have let those things affect me as much and just get me to the point where I'm unhappy and frustrated and kind of on a number of occasions having been like, I'm going to quit because of this, because this is complete nonsense. It doesn't make sense. It took me quite a few years to build out the resilience and perspective, to take a step back and say like, hmm, interesting.

9:43I disagree with this, but I just have to go about it in a very constructive way and not let it affect me and kind of make me upset or agitated or miserable or kind of any of it. So I think that would generally be kind of my, kind of if I could change and if I could come back and tell myself a couple of years into career, you know do something differently that would be the thing think would be trust the process and you know just kind of bring yourself into that constructive place rather than yeah I think a lot of people will empathize with that because I think a lot of people look back and I know certainly I'm not I'm no exception uh looking back earlier in your life and and you sort of identify times when you probably should have just taken a longer term view you know what I mean we think in very short term in short term way when you're younger don't you it's like what's going to affect me today what's going to have impact today when you know your career is a lot longer than that isn't it so um so yeah no that's a really exactly that i wanted to ask you about innovation google is renowned for having a very innovative culture they were quite quite groundbreaking in the i don't i don't know the correct terminology for this but i understand there was a kind of like a personal projects were encouraged and can you talk us through that i know some amazing applications have come from this culture, like Google Pay and some of the most amazing, impactful Google products of all, like Google Maps or whatever.

11:04But can you talk us through what exactly that was and how that experience was for you personally? So yes, there is a concept of Google of 20 % time, and it's not one day a week or even any particular kind of time in that sense. It's just the idea that as an employee, you can spend 20 % of your overall time at work doing something that you believe will make a difference and is important and it can be related to the main team or project you're working on or it could be a completely green field new idea new product new productivity tool kind of whatever you think makes a difference in in in that sense and yes quite a lot of innovation came out of it um i also remember my time when i was a manager of the team and you know kind of like to be perfectly honest it was frustrating that kind of at the times we're trying to ship and build a kind of something um really big as a team if a bunch of people would choose to use their 20 percent time around around kind of those those big dates uh so you kind of these things always just have come with pros and cons you just kind of want to be balanced in the assessment i do think it's brave for a company to choose to delegate autonomy to sometimes most junior people in terms of how they spend their time.

12:20I do think Google got quite a lot of value out of it in the early days. And then I think as it grew in scale, that math may have changed a little bit. And then I think the guidance for 20 % time also changed a little bit. But again, it was just one of those staples of early day digital native tech companies and kind of how they were thinking. Can I ask you about delegation? it's a it's an aspect of leadership which people i think is dramatically underrated people who can delegate well can do anything aren't they i mean it's uh it's such a superpower well um how how do you delegate well melena what what's the what's the what's the key to successful delegation i really try hard at when i delegate to make sure that the person has accountability for what they're picking up so i think that's the sort of uh i'm there to support and you know kind of in my role as a manager as a leader i'm there to coach i'm there to support but it is very clear to be for a person to understand that they're they're getting accountability to deliver something the flip side of that they're also getting the empowerment they're getting support they're getting you know you you have their back as a leader you give them this amazing opportunity but ultimately they're accountable for the results.

13:34So that's kind of how I think about it. And then one other thing that I always try to kind of bring into the equation is there was an old colleague of mine who made this metaphor, this kind of comparison of the work we do as leaders in technology to the work that athletics coach would do. So for example, someone who helps you train, your let's say lifting coach would only ever allow you to lift what's appropriate for you to build muscle but not to hurt yourself but equally they wouldn't let you lift too little because that might mean that you're not really building the muscle so just kind of when i delegate i always try to keep that in my head of like what is the appropriate weight i'm putting on this person you know i don't want to give them something that that doesn't help them grow but equally i don't want them to hurt themselves, so to speak, kind of by giving them too much.

14:27So I think those are probably two aspects of delegation that I tend to think about. I love that. That's a brilliant analogy. You know, I've used a similar analogy to that for burnout as well. You know, like you've got to give your brain a rest every now and again sort of thing. I've used that in that context. I've not used it in this context. I think that's a really interesting analogy. I might actually have to steal that one, Milena, but thank you for sharing. Sure, you can have it, Gareth. Thank you for sharing that. I think delegation is such an important one. I want to stay on the theme of your past and go back to the beginning, really.

14:55And I suppose the question I was going to ask was, how does a girl from Serbia end up in the UK? Can you talk us about how to end up working in the tech sector in the UK specifically? Can you talk us through why you got into the tech space and how you ended up in the UK? Oh, God, it was so long ago. Let me try to remember. I think I was always, it's kind of fairly canonical path, I would say, almost boring in the sense that I was always good at maths and you know i very early i got into maths competitions and physics competitions and then into programming reasonably early as well and into coding competitions and that kind of way so that was kind of very very canonical path in the sense that you know i was developing algorithms when i was 15 or 16 or kind of some subs yeah effectively something along those lines when i studied i think i was applying to various internships work placements you know kind of effectively stuff and stuff of that nature and google had a very open application process i sent my application not really actually seriously thinking that that i'll i'll i'll have any chance of them inviting me and they did and i interviewed over the phone and apparently i did well so kind of they brought me over to london to uh to do internship again that went well and i sort of uh i came back to to move i i fell in love with london i love the city i love the vibe and I was sort of like, oh, I think this is kind of a place for me.

16:18And ultimately, professionally, I wanted to go somewhere where I'm going to be challenged and just do the job at the highest levels of what is possible to be doing kind of in the sense of, yeah, just kind of building cool things and shipping stuff to millions or hundreds of millions of users. So I think all of those things sort of came together to get me on the path of technical leadership and living life in where I am right now. What was the biggest cultural shock for you when you come to the UK between the UK and Serbia what what was like oh my god what the hell is that was there anything very good what was that what was your biggest uh surprise well like I thought my English was very good having spent a lot of it like on the you know just online and having watched a lot of movies and stuff like that and oh my god like British accent was I was like oh my god I I'm genuinely struggling to understand this and more than anything I'm you know struggling to express myself in the way that I was used to so that was obviously language barrier was a big big challenge even though I thought of myself as flirting the human before I move.

17:17Culturally, purely, probably queuing, politeness. You know, it's kind of like, I think in Balkans, we do things a little bit differently, yeah. We do things a bit differently. But yeah, it's kind of now I'm sort of, I've been localized here to the local manors. So kind of when I go back to the old home, you know, it's always a bit more of a shock the other way. Yeah, fun. I just wanted to maybe skip forward now then and talk about your experience of joining trainline.com. I understand the organization's been going for a lot longer than I thought, actually. It was set up by Virgin Group, I believe, originally.

17:50It's been a bit of a journey since then, but it's certainly an app that I use regularly. And I think it's a household name in the UK, for sure. How did that opportunity come about? And talk us through why you joined Trainline. Yeah, as you say, Trainline has been around for 25 years. It's actually building technology for quite a few of those years. And that's, you know, for better or worse now, as I kind of have a lot of very modern tech stack, but also have some parts of the tech surface that have been around for a while. But yeah, so having been at Google for more than a decade, at some stage, I just got an itch to move on.

18:23And there was nothing I needed to run away from. It was a great company, took really good care of me. But at some stage, I just really wanted to see if I can add value somewhere else, if I can learn somewhere else. I'm just really, really itching to try something different. and we're very fortunate in in london or as a matter of fact it's a tech world in in many many cities that there was plenty of choice and you know i spoke to dozens of different companies i just i was really exploring what what feels right as as kind of as the next opportunity there was always something missing either company was great but a role wasn't quite right or company role were great but i wasn't as impressed with people or you know kind of like a lot of different kind of different circumstances and then train line came along and sort of everything really just clicked so this is going to sound a little bit cheesy but i really like the mission so i love connecting people to places in a greener more sustainable way i'm deeply concerned about the climate change if there is anything at all i can do to help make a difference with it in my nine to five and you know like rail being the greenest form of transport that we have uh you know like that that was something that really resonated it was deeply meaningful uh for me and then on top of that i was also a user of the product i i liked it and uh at the same time i also felt you know kind of there is even more we can do i i saw it both both as something that's uh successful and good that you know has plenty of users and of course has a proven business model and and kind of is a actual company that i don't have to worry about will will you know will he be able to pay the bills in in a year or two but at the same time i could see that it can go it can be so much more so the opportunity felt right the product felt right and then more than anything i was so impressed with people the you know the ceo and my boss my product counterpart chief people officer so many fantastic leaders that kind of i had a lot to learn from so yeah everything fell into place.

20:19And I've just been having fantastic last two and a bit years. What sort of engineering and technical challenges have really sort of excited you since you've joined? You know what I mean? Are you able to talk us through any significant change that you've taken the organization through from a technology standpoint? The thing that was not obvious to me before I joined was where does the complexity lie in this space? And one of the key examples is rail travel is different to all the other forms of travel because of the traffic patterns and because how you do it. Quite a few companies have solved this air travel aggregation or hotel aggregation type problems.

21:00But rail is harder because there are about a thousand times more train stations in Europe than there are airports. So just the scale of the problem, especially the, you know, obviously the combinatorial complexity of that is just kind of orders of magnitude. higher and then traffic patterns are very different whereas you would book your airplane ticket weeks in advance sometimes months in advance very many of our users the double digit percentage of our users are buying tickets as they walk into train station as they're approaching barrier gates so for us that makes some very interesting you know morning commute peaks and after your commute peaks to a lesser degree but certainly morning commute peaks which are very very interesting technical challenge we have to deal with but equally the requirement to fulfill a ticket to give users that barcode they can scan on the on the barrier gates as a matter of seconds or you know very often under a second from the moment they buy which is not the case for so many of the the bookings related to well almost anything else almost anything you buy online company can have you know hours to fulfill your order to send you either the ticket or to ship stuff to you so just this immediacy of transaction combined with the scale combined with the traffic patterns kind of that that follow the sun so to say so those are just technically some of the so keeping services up and running through what has been you know significant growth in our traffic post-covid has been like a very interesting just core technical challenge so kind of enabling scale and reliability has been one of the key things.

22:36And then there are obviously many other things of kind of moving to the next generation of cloud and so on kind of as we do that. But I think this is where it really kind of the challenge, hopefully you get to see where the challenge really comes to life. Can you give us an idea of what sort of, I don't know how you would measure it, but in terms of transaction volume, I'm assuming train.com, the transaction volume is insane. Can you give us an idea of what the transaction volume looks like And what technology and engineering challenge does that pose to trainline.com going forward? Maybe you can go into the cloud stuff you were talking about.

23:10Yeah, for sure. So we do more than a thousand transactions per minute at peak time. So that's the, which is, you know, really, really, pretty, pretty, pretty significant. And, you know, certainly even something with my, you know, putting my Google hat from back in the day, you know, it's something that is respectable. because obviously our people who are just checking train times and coming into our app or getting tickets is even higher, significantly higher. But just the transaction and ticket fulfillment, which is obviously the most intensive and the mission-critical part of what we're serving is kind of more than 1 ,000 per minute, which is quite significant.

23:46Just to clarify, is that UK or is that European-wide? Let's say that would be global and things do look different on kind of different days or times. you know we see our european peaks and we see our our kind of uh british peaks but the you know for example earlier this week we had sncf the the main train operator in france was doing a significant sale over which and i don't want this to sound as some sort of shiner freudy but um their services went down because they were doing the massive big christmas sale and everyone was trying to buy through them their services went down train lines stayed up and just on that we were dealing with you know six seven hundred transactions per minute just in france so obviously you know this looks different in kind of in different countries but very regularly globally we like daily really we handle more than a thousand transactions per minute that's a lot just in terms of the technology challenges and how do you see train line dealing with that kind of level of transactions growing in the future what what is your sort of contingency plan for growth on from from a technology standpoint?

24:50So one of the big transformations we're doing right now is we're moving from sort of, I guess, what was cloud 1.0 to what cloud is now. So Trainline has moved the cloud fairly early, something like seven, eight years ago, which was very good at the time. It was kind of a little bit at the forefront. It was the right thing to do. However, cloud seven or eight years ago was very different to what cloud is today. In a way, we effectively ended up shipping a bunch of services from on-prem, kind of data centers, to EC2 instances in AWS. And really only now, we're kind of starting to adopt the latest generation of cloud that kind of started to emerge in the last couple of years, which is containers and cloud-nated databases rather than relational databases hosted in EC2 and so on.

25:41So that's one of those things that I think will give us planetary scale, so to speak. It's kind of like infinitely, horizontally scalable services. I find that stuff fascinating, but I'm sure you've got plans to modernize the infrastructure there. So just staying on the topic of Trainline then, it's an organization, obviously, that has been around for a long time. I'm just wondering what you guys are doing to modernize your service delivery to your customers and things like that. And I specifically want to point this towards AI. What kind of conversations are you having at board level in Trainline at the moment to benefit from AI technology?

26:19It's certainly something we're looking at. You know, generative AI has so much potential. And myself as a technologist personally, I'm very excited about it. And of course, the leadership team at Trainline is very excited about it as well. It's a really interesting challenge. We already use machine learning fairly extensively. you know kind of and you know there's so many good things we're doing like split save and price prediction and kind of a lot of our customer features that are already driven by by machine learning in that form that paradigm of of machine learning just to be clear split save is the one whereby instead of buying a ticket from cardiff to london you'd buy a ticket from cardiff to swindon and then a ticket from swindon to car to london which would work out cheaper is that is it that exactly that's great that is by the way yeah yeah i know i know we get a lot of positive on it then you know i think the best thing is that obviously users don't have to do that manual work we you know they buy a single ticket and we just kind of split the thing on their behalf and you know kind of uh very often they don't even have to move the the seat in the train and that's that's you know kind of helpful in that way so yeah it's kind of quite quite a few of these machine learning driven and kind of big data driven features already so we kind of in a way we see generative ai as an enhancement of that and where i think and you know my mike hyde my chief data officer can talk to you in a kind of much more, I would say, extensive and compelling way.

27:40But like the way we think about generative AI is sort of something that can solve broader, more complex problems rather than machine learning where I think machine learning is exceptional right now in kind of given a set of inputs and a very clear expected output, usually like a classifier style or kind of the vector machine style output, that problem is solved and cater very well with the current paradigm of AI. With LLMs, we are really hoping to get into kind of more complex problems, which could be something like, I'm coming from US with a family of four and we have two weeks. We want to do journey across Europe on trains.

28:20Tell us where to go and kind of recommend itineraries with specific trains and kind of like this. Something that's just simply less constrained in the nature. And we're looking at a lot of aspects of this, It's mainly things like, or among other things, can we build UIs that are not purely chatbots or plugins to other chatbots? Can we use the reasoning of LLMs and generative AI to drive the experience in a way that I would say still comes more naturally to users, which is clicking on the parts of the screen on a mobile phone? And yeah, we're already kind of having some early success, whereas I don't have anything to announce today.

29:02I'm hoping kind of over the coming months there will be kind of a first release in our app that uses all this technology. Yeah, for sure. How have you managed to, in terms of like attract the right talent to keep Trainline at the forefront with this type of thing? Do you typically hire from the market and hire experienced people or do you have more of a policy of growing your own? How do you develop talent for your team, Melaina? Yeah. Yeah. I, this is deeply important for me as someone who stayed in one company for more than a decade and was promoted six or seven times, wherever it was. I deeply believe it's important to give people a chance at a company to advance and grow and kind of to give them that career ladder.

29:45So it's kind of a little bit of everything you said. Of course, we hire from, from, from the market, like I think fresh blood and your perspectives and, you know, people who have done jobs successfully elsewhere i think that that that is important to a certain degree for sure but equally it's important to have retention rate on the team that's high enough that the critical knowledge domain knowledge and systems knowledge is being retained so that that people you know can can stay can still advance can continue to learn and continue kind of to contribute and sort of force multiply their contributions because they've been around for longer and they know the people they know the stack they know the domain and and and so on did quite a few different things to be honest like a lot of my time does go on activities related to this with a team we have recently redefined our career progression ladders to extend our individual contributor ladder beyond senior into staff and senior staff and eventually distinguished which kind of puts senior individual senior engineers senior individual contributors on par with directors if their impact is commensurate with that meritocracy and developing talent is just so like mobility is so important isn't it you know what i mean no that's a really good answer i'm glad to hear it um there's loads of directions we could go in with that but i really want to ask you about something and uh apologies if this is like not something you really care about but um what do you think about hs2 getting scrapped did you guys think about did you discuss that much at trainline.com?

31:14Do you have an opinion on it? Yeah, frankly, right now, there is quite a lot going on for us in terms of strategy planning for next year and performance review cycle for everyone on my team and a lot of other exciting things in terms of what we're actually building for customers and shipping and all that. So, whereas I know certain parts of the team and organization are looking into aspects like this, like infrastructural development in the UK, as well as our key markets in Europe, like France, Italy, and Spain, it's not something that I kind of sweat day to day. So like, I don't have anything, you know, particularly interesting to say on it.

31:48We talked about AI earlier on. Obviously, you're a technologist at heart. It's in your blood, you know, what technology innovation, and it doesn't have to be related to your role, it can just be in general, what technology innovation in the world right now, Melania, are you most excited about? Oh, very good. So I bet everyone talks to you about generative AI, kind of all that. So I will spare you that just for now. Where I'm actually very excited is kind of biotechnology and I would say sensors, if anything else. Like I feel that field is developing quite a lot and it's really helping us, you know, in terms of improving our health and leading healthier lives, but also just really getting more out of technology.

32:33You know, I think with everything that's now being put into wearables and getting information out of that, I think that's probably where I would be most excited. So in terms of the bespoke data that comes from wearables specifically is really exciting, isn't it? Like sleep analysis, for example, is amazing, isn't it? I don't know if you're into that type of thing. Yeah, and I tend to be a bit of a data nerd, so kind of any chart... We all are, don't worry. I would always be like, oh, isn't that interesting? What am I learning out of this? So yes, for sure. For sure. So this is a bit left field, but I really wanted to ask you about the role of a CTO, okay?