How Trainline’s CTO stays on track with professional development

Few would trade San Francisco sunshine and Silicon Valley innovation for a rail ticketing company serving disgruntled British commuters, but try telling Trainline CTO Milena Nikolic.

A lifelong Googler, who as Director of Engineering saw her lead the Google Play developer ecosystem, Nikolic wanted something new that offered a greater sense of social purpose.

I was at Google so long that I stopped counting,” she says. “It had been almost 13 years…and I was craving a bit of a change.”

In a growing technology market, Nikolic waited for the right opportunity. Nothing clicked until she spoke to Trainline, the international digital technology platform for trains and coaches, headquartered in London.

“Everything fell into place; every box was checked,” she says. “I really liked the mission, connecting people to places in a greener and more sustainable way.”

The first 100 days

As the new CTO tasked with setting technical strategy, delivering technical team delivery, and aligning product and business strategies, Nikolic had a lot on his plate for the first 100 days.

She spent time understanding the technology stack, business challenges, and a full technology team split between infrastructure, product development, security, privacy, and technical compliance.

Trainline had strong technical systems and a good level of autonomy, but Nikolic believed that team members themselves felt less able to step out of their comfort zone, which impacted results commercial.

“We had engineers who were really good at their stuff, but I think people felt less able to really own the end-to-end goals and outcomes,” she says. “It’s all these brilliant people who have a lot to add beyond coding their part of the technical system. They were more glued to their part of the tech stack and just contributing to that.

This thinking drove Nikolic to make changes to the way technology teams worked across the organization and support a new target operating model.

Drive business growth with new teams

Trainline has been a technology-driven company since its launch in 1997, with online ticket sales available from 1999. More recently, under former CTO Mark Holt, Trainline has grown into a story of scale and mobility , moving to DevOps, agile principles, and leveraging computing power through Amazon Web Services (AWS).

In 2018, the Trainline platform hosted more than 80 million customer visits per month, more than 80% of them via mobile devices. The company sold over 204 tickets every minute.

Today, its One platform, with 78 million visits each month across all channels, covers more than 270 rail and coach companies in 45 countries, including more than 80% of rail routes in Europe.

Milena Nikolic

Such large-scale growth has resulted in a steady increase in resources. Despite the COVID-19 pandemic pushing the company to nearly £250m in debt in 2021 (the company has since recovered to achieve net ticket sales of £2.5bn and a profit net of £90m in its latest financial results), Trainline now employs around 400 engineers, data and technology specialists who work on Platform One and process over 600 system releases each week. The company has approximately 800 employees in total across the company.

Since joining a year ago, Nikolic has divided its teams into horizontal and vertical functions to support operational efficiency and product development.

Horizontal team members own the platforms to ensure their robustness, reliability, latency, and scalability so engineers can be productive. Vertical teams, on the other hand, operate across the entire technology stack, so they are not localized to certain operating systems, orchestrations, or data layers. These cross-functional teams, including product support, user experience, and data, offer different levels of expertise on front-end and back-end infrastructure.

“These teams have a clear mission…that they own the product or the business outcome,” says Nikolic. “They have complete autonomy to decide what they want to do…to achieve this goal, this mission and move this forward [business] metric in the way we expect.

Training of engineers and building products

As part of reskilling teams, Nikolic has focused on building a T-shaped skill set and allowing staff to gain broader experience. For example, she says an iOS developer could learn e-commerce, or a web developer could study back-end infrastructure.

There have been a number of vehicles to do this, from an internal ‘tech summit’ with speakers from within and outside Trainline presenting on all things technology, product and data, to a community of “Craft Culture” which offers regular activities, such as coding dojos, workshops, hackathons and meetups. The company also provides access to the O’Reilly Technology Learning Platform, where team members can attend live conferences and access books and content.

The team celebrated many accomplishments in its first year. Nikolic says Trainline now has a robust and scalable platform capable of supporting 10x search traffic and transactions, while the company recently launched STicket barcode technology to reduce friction when shopping and prevent fraud. It also launched delay notifications in France and the UK – a smart move considering 600 combined train delays every minute, while the new Trainline What is the next step ? The app integrates with Apple MapKit so iOS users can plan their trip without having to leave the app.

Platform One is the strong foundation for all technology and innovation at Trainline, with microservices and infrastructure as code (IaaC) both in vogue.

“Our technology stack is built on a solid foundation provided by AWS,” she says. “Using a variety of technologies, such as EC2, ECS, Fargate, Kinesis and RDS, Trainline is able to realize the large-scale infrastructure needed to enable us to provide our customers with a world-class platform.”

Attracting more women into engineering

Having worked in the industry for 15 years, Nikolic remains frustrated with a leaky pipeline when it comes to women in engineering. She admits the tech industry can still feel less inclusive for women, and this “society issue” can push women out of the industry mid-career.

“It’s difficult, of course,” she says, “and, having been in this fight for 15 years, it can be disheartening at times, how slow the pace of change is.”

Nikolic, however, hopes the industry can narrow the representation gap. She cites examples at Trainline, where the company has set up various recruitment panels and D&I targets, as well as partnerships with the ADA school of coding technology in Paris and Future Frontiers, a charity that equips students from disadvantaged backgrounds in 200 secondary schools in London and Edinburgh.

She believes the key to improving the number of women in engineering is adding more talent to the top of the field, for example by nurturing disadvantaged groups in school into early-career careers.

“The only sustainable way for us to prove this is to break down barriers for underrepresented groups as they enter the tech world,” she says.

Trainline remains on an upward trajectory. There is reported international expansion on the horizon, government contracts up for grabs and a new CDO, hired by Meta, who now reports to Nikolic. “I really want to make sure we’re executing well,” she says. “If there’s anything that keeps me up at night, it’s making sure the team is set up to succeed in the best possible way so that we capitalize on those opportunities.”

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