The finale of automatic platform gate retrofit at MTR heavy rail network

By MTR Corporation

A complete engineering perspective introduction: A vision realised

The completion of the Automatic Platform Gates (APG) retrofit on the MTR East Rail Line (EAL) marks a major milestone in Hong Kong’s railway modernisation journey. This represents a significant advancement in both safety and passenger experience, fulfilling a long-held objective for a robust and future-ready railway.

Retrofitting APG on a century-old, fully operational railway such as the EAL was a formidable task. The project’s success demanded strategic foresight, technical precision, multilateral collaboration, and unwavering commitment. Completed six months ahead of schedule, the final installation at Mong Kok East Station in May 2025 concluded one of MTR’s most complex infrastructure upgrades and highlighted the ingenuity and perseverance of the teams involved.

Given the project’s high visibility and operational complexity, clear communication and continuous stakeholder engagement were essential. The team maintained a robust communication framework by regularly engaging with stakeholders through briefings, ensuring transparency and fostering trust at every stage. Strong relationships with stakeholders, and the buy-in from passengers, were the catalysts for the smooth and timely delivery of APG on the EAL.

With the completion of APG retrofit, all heavy railway stations in Hong Kong are now equipped with APG or Platform Screen Doors, ushering our city’s railway system into a new era of a customerfocused commuting experience with enhanced operations.

This article explores the engineering journey behind this remarkable project that has transformed Hong Kong’s most historic railway into a modern, resilient, and passenger- centric piece of infrastructure.

Modernisation of infrastructure

The successful installation of APG on the EAL reflects MTR’s meticulous planning and well-thought-out strategy to upgrade legacy infrastructure with cutting-edge technologies. There were several essential steps to prepare our oldest railway for APG operation, including signalling system upgrade, platform transformation, a new fleet of 9-car passenger trains, new train stopping position at platforms, and preparatory works for APG installation.

Preparing a century-old railway for the future

At the heart of this preparation was the replacement of the former signaling system with a state-of-the-art Communication- Based Train Control (CBTC) system. This upgrade enabled precise train stopping and provided the synchronised control of APG and train doors via the signalling system.

Platform transformation was another essential component. Each of the 13 stations (which encompasses 35 platforms) had to be structurally upgraded to bear the additional weight of the APG equipment, approximately 20 tonnes per platform. The reinforcement process was tailored to the unique conditions of each station, many of which featured curved or open platforms and have been in use for many decades, all these posed additional challenges for designing and implementing the structural upgrade while maintaining the precision required for the latter APG installation.

Complementing the signaling and platform upgrades was the deployment of a new fleet of passenger trains, featuring widened cars to reduce the platform gaps along EAL, effectively addressing one of the operational challenges. With the new fleet in service, and the adjustment of train stopping positions to match the APG configuration at each platform, the installation of APG was able to commence.

As part of the APG installation pre-works, the team also prepared each station by installing concealed mounting plates, laying prefabricated cable underneath the platform, and setting up and testing room equipment using simulation tools when the aforesaid upgrades were taking place. These behind-the-scenes efforts were critical to enable the seamless commissioning of the APG system.

Together, these carefully sequenced and interdependent upgrades marked the culmination of a long, meticulously planned journey to future-proof the EAL.

Extra: Targeted safety enhancements for curved platforms

MTR introduced new platform gap risk control measures in conjunction with APG installation at selected platforms with more pronounced platform curvature at Lo Wu, Mong Kok East, and University Stations. The measures include LED steel floor plates that lit up upon train arrival, widened platform gap fillers, and enhanced visual cues such as “Please mind the gap” signage and high-contrast markings on the APG facing the trackside. They are designed to improve visibility and awareness for passengers boarding and alighting, particularly where platform gaps are present due to platform geometry.

Also, since APG and Platform Screen Doors have now been integrated across the network, MTR has standardised safety and accessibility features, as well as enhanced passenger flow management.

From platform layout to logistics, and plan the works accordingly, as works were carried out in a live environment where even the smallest mishap could ripple into the next morning’s train service.

Pushing the boundaries of railway engineering

APG retrofit of EAL was not a task that could be treated lightly despite the already paramount effort invested in the preparation works. In fact, it was one of the most demanding engineering undertakings in Hong Kong’s railway project history. The EAL was never built to support the structural and operational requirements of modern APG systems. Even after the substantial platform transformation, the EAL’s characteristics, shaped by decades of evolution, such as steep platform curvatures, narrow clearances, outdoor platform that exposes to weather elements directly, all posed substantial challenges to the APG project.

To overcome these constraints, innovative solutions were implemented that went far beyond conventional engineering approaches. The following section presents how MTR executed this complex retrofit project, demonstrating its ability to deliver infrastructure modernisation with speed, accuracy, and consistency across one of Hong Kong’s most challenging transit environments.

Precision design and 3D simulation modelling for smooth installation

To address variations in platform level and platform curvature among different stations, and for sometimes even along the same platform, the team collaborated closely with the APG supplier to develop a base plate installation-and-calibration system, among the team referred to as the “horseshoe”, which is custom built to suit shallow platform recesses in the EAL environment.

“Horseshoes” formed the foundation of the entire APG installation methodology and allowed APG installation on platform in a straightforward, plug-and-play style. Its core merit is the ability for precision adjustment on-site and consistency of approximately 1,600 APG of EAL.

Intensive surveys were also conducted for all 35 EAL platforms during the design phase to create a 3D simulation model, to map out the APG panel installation across different platform geometries whenever straight or curved. This model helped design the accurate calibration required for positioning the “horseshoes” and various widths of glass panels, ensuring that APG panels aligned perfectly as a continuous line, even for curved platforms.

Same-night installation and commissioning: the Hong Kong approach

With the design solution in place, the next challenge lay in execution. Railway retrofit projects in other countries or regions often involved shutting down entire lines or segments for days or even weeks to carry out infrastructure upgrades. This is a common strategy due to complexity to maintain regular passenger service in midst of a significant infrastructure upgrade.

In contrast, one of the defining features of the past APG retrofit in Hong Kong was the practice to install and commission APG within a single night, all within a strict “golden two- hour” window, and EAL APG retrofit was not an exception.

This approach, known internally as “Same-night commissioning,” is particularly suited to Hong Kong’s unique situation, where shutting down railway lines for extended periods of time is not feasible due to high passenger volumes and heavy reliance on railway service.

While “Same-night commissioning” eliminates the service disruption of an operating railway, it introduces broader logistical and technical challenges, and significant coordination with the operators.

To ensure flawless execution, the team carried out extensive rehearsals both offsite and onsite. Offsite trials helped refine the installation sequence, test lifting operations, and calibrate tools in a controlled environment. Onsite rehearsals included full dry runs at Racecourse Station, allowed the team to simulate the entire process and develop a minute-by-minute plan that fits within the “golden two-hour” window.

Every minute of the “golden two-hour” window was accounted in the plan which detailed sequencing and contingency arrangement, ensuring that the installation proceeded smoothly and without disruption to daily operations.

Forethought of system integration

To prepare for “Same-night commissioning”, the team leveraged their experience from the APG retrofit in Ma On Shan Line, and began the installation design with rigorous system integration planning. A key enabler was the use of APG simulators, which allowed validation of the interface between the APG control system, the newly upgraded CBTC Signaling system, and a new fleet of trains well before the actual APG installation at platform took place. This innovative testing methodology helped reduce commissioning risks and ensured that the APG-Signalling-Train interface would operate smoothly and reliably once APG are installed.

Coordinated execution

The scale of coordination required was equally impressive. As the project spanned across multiple stations and diverse teams, it demanded extensive planning, precise resource allocation, and rigorous testing. Thousands of installation shifts were carried out during the day and at nighttime, supported by comprehensive train reliability runs and APG cycle tests.

Coordinating such intensive night test required not only technical expertise but also a deep operational awareness to an operating railway. Numerous departments within the Corporation have been involved since the planning stage, to name a few, Construction Management, Capital Works Technical, Project Planning & Development, Railway Business Segments, Operations Engineering Group, and etc. Every team member had to understand the limits imposed by various conditions at the operating platforms of EAL, from platform layout to logistics, and plan the works accordingly, as works were carried out in a live environment where even the smallest mishap could ripple into the next morning’s train service, which is a unique feature of Hong Kong where train service is the major means of commuting.

EAL APG retrofit project lays the groundwork for the next phase of railway evolution where modern engineering solutions are deployed with precision and scalability. While the success of the APG retrofit in such a complex live railway environment hinged on flawless execution, a shared awareness that every action had immediate consequences for millions of commuters helps MTR to achieve zero interruption to passenger service. Hong Kong’s model demonstrates that with the right tools, planning, and team expertise and collaboration, complex retrofits can be executed with minimal impact on daily operations. It offers a compelling alternative for cities seeking to modernise historic railway conditions without compromising service continuity.

Extra: Advanced object detection

To further improve safety and reliability during boarding and alighting, particularly on curved or outdoor platforms, MTR introduced a new generation of object detection technology as part of the EAL APG retrofit. This system, based on per-door detection, was designed to monitor the space and if anything/ person stands between the train and the platform gates with greater accuracy than previous solutions.

Unlike earlier detection methods, which were more susceptible to environmental interference, the new laser-scanner based system performs reliably in exposed outdoor settings, which is a unique challenge for EAL. Each sensor was carefully calibrated to its specific location, ensuring consistent performance and increase system stability across all nearly 1,600 APG.

Efficiency and execution: Turning innovation into action

When implementing a large-scale retrofit like APG in the EAL, which pushes the boundaries of railway engineering, innovation alone will never be enough. In fact this demands a practical, repeatable execution strategy that delivers consistent results under diverse conditions.

The APG retrofit of EAL was driven by clever design, technical ingenuity as well as a disciplined implementation approach that ensures consistency and quality. Strategic planning which started from the beginning of the project was the key success factor: modular construction, synchronised logistics, and adaptive workforce deployment enabled rapid progress without compromising safety or service continuity.

From early-stage rehearsals to minute-by-minute installation planning, the team focused on workflows that could be scaled across all 35 platforms. By translating complex engineering into efficient, real-world action, the team turned an ambitious infrastructure upgrade into a model of operational success.

Quality assurance as the foundation for Modular-in- Construction (MiC) success

Recognising that quality control was essential to the success of the modular construction strategy, the team maintained oversight throughout the manufacturing process. This included regular site visits to inspect the manufacturing and quality of major components, such as glass panels and structural steel frames, and to verify those key elements met design specifications.

Tailor-made features such as cable marking were built into the APG panels to allow plug- and-play installation and improve speed and accuracy of the work.

Close collaboration with the manufacturer ensured that each unit was thoroughly checked for quality compliance through Factory Acceptance Test before delivery. This proactive approach to quality assurance has maintained consistency across all APG units and has reduced the risk of delays or rework during installation.

Delivery and storage logistics

Delivery planning posed a significant challenge due to the constrained layouts of many EAL platforms, some of which have been in service for nearly half a century. Long and narrow platform designs, combined with limited lift car spaces at stations like Fo Tan and Tai Po Market Stations, made transporting and maneuvering large APG panels particularly difficult.

To overcome these constraints, the team developed a station-specific delivery strategy. Depending on the site, APG panels were either transported via road access or delivered by engineering train from the Lo Wu Marshalling Yard. Coordination with station operators was continuously carried out during the installation period to ensure and secure the transport routes, storage locations, and packaging requirements, all tailored to the specific platforms.

Following the transition from the former 12-car to the new 9-car trains, spare platform space at each end was repurposed as temporary storage area for APG panels. This allowed for early preparation and efficient installation once track access became available. The logistics for APG installation during the “golden two-hour” window highly resembled the puzzle game “Sokoban”, storage configurations were carefully choreographed using a “first-in, first-out” principle to synchronise with the step-by-step installation rundown.

Scaled execution with precision

Maintaining this highly precise and challenging APG installation across multiple stations simultaneously demanded a perfect planning and coordination. Drawing on experience from previous APG retrofits of the Tsuen Wan Line, Kwun Tong Line, Island Line, and Tuen Ma Line, the team implemented a rotational workforce model. Skilled crews moved efficiently between sites, enabling parallel installations while maintaining consistent standards.

The detailed scheduling and contingency planning on deployment of work forces had accounted for everything from weather conditions to ad-hoc operational needs to occupy the installation site. This allowed the team to maintain momentum when faced with unexpected changes.

A culture of continuous refinement

As confidence in installation and commissioning of APG in under two-hour grew, so did the ambition to further advance the program. Installation activities were extended into non-peak daytime hours for stations with spare platforms, dramatically accelerating progress. APG installation that once took months per platform was reduced to mere weeks.

Even the tools evolved over the installation period. Calibration kits for the passenger detection system were refined for greater accuracy. Installation rigs were customised to suit narrow and curved platforms. Modular construction techniques were further optimised to reduce on-site adjustments and improve repeatability. These enhancements weren’t just technical upgrades; they were reflections of a team committed to learning and adapting in real time.

Speed without compromise

The project proved that speed does not have to come at the expense of safety or performance. Intensive offsite and preinstallation testing, including millions of APG cycle tests and extensive train reliability runs, ensured every element met a high standard.

Although the installation spread across both Non-Traffic hour windows and non-peak daytime hours, there were no recorded events of APG installation that affected the train operation of EAL.

This seamless execution reflects MTR’s expertise in managing complex infrastructure projects. It highlights the organisation's ability to integrate innovation, planning, and operational discipline into a cohesive delivery model.

Building public trust through transparency and engagement

A project in full view

Let us be reminded that the APG retrofit was unfolded in full view of the public instead of just an engineering solution. Unlike typical infrastructure upgrades that occur out of sight, this retrofit took place on an operating railway day-afterday, night-after-night, with trains running and passengers commuting daily. That meant every step of the process from platform transformation to APG installation was visible to millions. The team understood that this visibility came with heightened expectations and scrutiny.

Proactive transparency

In response, MTR adopted a proactive communication strategy rooted in transparency. The team consistently anticipated questions from the public. Regular updates were shared through media briefings and site visits, and social media channels. Stakeholders including Legislative Council and District Councils members, professional bodies and counterparts from government departments were invited to observe the work firsthand, reinforcing the message that the project was progressing with care and accountability.

Clarifying public misconceptions

One of the most valuable outcomes of this transparency was the opportunity to clarify misconceptions. Many assumed that installing APG was a straightforward task, or that it could be completed overnight. Through open engagement, the team helped bust these myths: explaining the complexity of retrofitting gates on curved platforms, the immense challenges to fit all the engineering steps in the “golden two-hour” window, the precision level required for installation of APG to allow the newly installed APG put into service right after installation. This kind of myth busting helped shift public perception from impatience to appreciation.

“This project is highly visible; a great expectation has been cast on us from all sides.” said Carl Devlin, Capital Works Director of the MTR Corporation. Efforts on proactive communications has paid off well in winning the support of government partners and the understanding of the passengers, which enables the smooth completion of the project with a twist of skepticism in the beginning stage to appreciation and positive sentiment upon completion of the project.

Reinforcing safety and service quality

Beyond communication, the APG retrofit reinforced MTR’s long-standing commitment to safety and service excellence. The installation of APG / Platform Screen Doors across all heavy rail stations marked a major milestone in the corporation’s asset enhancement strategy. The project responded to public expectations for safer, more accessible, and more comfortable travel experiences.

Inspiring the next generation

The EAL APG retrofit stands as a case study in how technical achievement is built through innovation with iteration. By revisiting, rethinking, and refining each step of the process, MTR has shown that the path to success is not linear but adaptive. And in a live railway environment, where conditions shift and expectations rise, that adaptability is what makes excellence sustainable.

The project also became a platform for education. Engineering demonstrations, school placement programs, and job shadowing opportunities allowed students and young professionals to engage with the project in meaningful ways. These initiatives offered a rare glimpse into the complexity of railway modernisation and helped inspire future talent in the transport and engineering sectors.

A reputation strengthened

In every respect, the EAL APG retrofit has strengthened MTR’s reputation, as both a transport operator and a trusted partner in Hong Kong’s urban development. By combining technical excellence with public engagement and educational outreach, MTR set a new benchmark for how infrastructure upgrades can be delivered on an operating railway in a densely populated and highly connected city.

As each train prepares to depart and the APG closes firmly in place, it quietly opens the way to a future where journeys by MTR are not only safer and smarter, but also shaped by the people it serves and the possibilities it dares to pursue.

Conclusion: A model for urban rail transformation

The completion of the EAL APG retrofit marks more than just the end of a project, it marks the beginning of a new standard in urban rail transformation, and a milestone of Hong Kong’s railway development.

“Completion of APGs is taking MTR to a new chapter. All our heavy rail stations now are equipped with either APGs or Platform Screen Doors, providing passengers with improved services and travel experiences as well as one major step of MTR’s asset enhancement.” said Carl Delvin, Capital Works Director of the MTR Corporation.

What started as a bold aspiration over 15 years ago has culminated in a milestone that redefines what historic railway conditions can achieve when guided by vision, collaboration, and a commitment to public value.

The APG retrofit was not just about installing APG on an operating railway. It was about reshaping Hong Kong’s oldest railway line to meet the expectations of a modern city without sacrificing the ease of our passengers. The challenges were overcome to bring APG to life: curved platforms, structural constraints, legacy signaling, and the need to maintain uninterrupted service. Yet, through adaptive engineering, seamless coordination and forward-looking planning, MTR delivered a solution that is both technically sophisticated and deeply passenger focused.

Throughout the journey, the project demonstrated how innovation and execution could evolve hand in hand. From simulator-based system integration to minute-by-minute installation programs, the project never stops improving from refining tools, workflows, to strategies that help speed up the project program while fitting the demanding operating railway environment. The result was a retrofit completed six months ahead of schedule, with zero disruption to train services.

This culture of evolution extended far beyond engineering. It defined how the different teams in MTR proactively coordinated, transparently communicated, and agilely responded to emerging challenges. Whether adjusting schedules or improving safety protocols, the team demonstrated successful infrastructure delivery with responsive discipline.

Equally transformative to the internal communication was the way the project engaged with the public. As highlighted earlier, the retrofit unfolded in full view on platforms used daily by hundreds of thousands. The team understood that visibility came with responsibility. Through proactive communication, media briefings, and community involvement, MTR built trust not just by delivering results, but by inviting the community into the process. Expectations were managed, and support was earned. The absence of complaints and the abundance of praise reflect a public that felt informed, respected, and included.

The EAL APG retrofit project also extended its impact beyond infrastructure. Educational outreach, job shadowing, and community programs turned the project into a platform for inspiration showing young people and future engineers what thoughtful, responsive transport innovation looks like in practice.

As cities around the world face the challenge of upgrading aging transit systems, the project offers a compelling blueprint. It proves that transformation is possible even in constrained environments. Service to the public remained at the heart of every decision made for the APG retrofit project.

The APG now installed across EAL are more than safety barriers. They are symbols of progress, of a railway that listens, adapts, and leads. When MTR turns the page to its next chapter, it does so with a renewed commitment to smarter, safer, and more connected journeys that builds on the values this project so clearly exemplified.

As each train prepares to depart and the APG closes firmly in place, it quietly opens the way to a future where journeys by MTR are not only safer and smarter, but also shaped by the people it serves and the possibilities it dares to pursue.

About the authors:

Evan Lau
Senior Engineering Manager – System Integration (Capital Works)
Railway & System Integration
MTR

Maggie Chan
Chief Engineering Manager – System Integration (Capital Works)
Railway & System Integration
MTR