Community of Metros Research

Research: Decarbonisation of Metro Operations

Metros worldwide are working to reduce greenhouse gas emissions, but approaches to measuring and reporting vary. This study helps metros quantify emissions across Scopes 1, 2, and 3, highlighting the importance of consistent reporting and the role of metros in broader regional decarbonisation through mode shift and compact development. It draws on responses from 34 metros and summarises key initiatives to reduce emissions as well as emerging innovations carried out by members.

Washington DC WMATA’s ‘Metro Rewind’ website

Many metros now face increasing requirements to report greenhouse gas emissions. To meet sustainability goals, metros typically adopt emission-reduction or net-zero targets aligned with national timelines, supported by improvements in renewable energy supply and increased metro ridership.

Reducing emissions requires actions across all scopes, including electrifying vehicles, improving energy efficiency, sustainable procurement, and low-carbon construction. Metros also reduce regional emissions through avoided car travel and can leverage carbon credits and trading systems to support net-zero ambitions.

Research: Reducing Passenger Safety Incidents

Despite metros being a very safe mode of transport, any incident, however rare, can attract significant public attention and erode trust. The study examines passenger safety incidents within stations, focusing on vertical circulation (escalators and stairs) and platform-train interface gaps. It builds upon findings from COMET’s Safety Performance Indicator (SPI) analysis using additional member contributions to identify trends, underlying causes, and effective strategies for reducing the risk of passenger safety incidents.

Example image of gabo light projection at Sydney Metro

Research: Video Analytics for Safety and Security

In the past two decades, metros around the world have been transforming the way they approach safety and security. One key aspect of that is the use of emerging technologies, such as video analytics. The COMET case study brings together responses from 34 member metros and covers the challenges, solutions, and best practices related to video analytics in metros, including a range of examples of using Artificial Intelligence.

Video analytics have specific impacts on different types of incidents and wider impacts on metro systems. The study reviewed areas where video analytics had reported impacts. 71% of the responding metros reported video analytics to be ‘very effective’ in enhancing their safety and security, and identified future opportunities for further development of video analytics in their systems.

Research: Air Quality in Metros

Poor air quality in metros can discourage riders, risk the safety of staff, and attract negative media attention. The Air Quality study examined how COMET metros monitor and manage air quality in their systems. It is focused on underground stations and onboard trains where pollutants can accumulate.

Metropolitano de Lisboa’s air quality dashboard

The report outlined the strategies metros have used to improve indoor air quality, including strategies that prevent emission of pollutants, reduce pollution concentration, and keep customers away from poor air quality. The study summarised the key recommendations to metros based on good practices identified from 30 metro organisations.

Research: Metro Automation

Automation offers potentially transformative benefits to capacity, reliability, safety, energy use, service flexibility, costs and customer experience. Several metros have embarked on transformative brownfield automation projects, upgrading legacy infrastructure to Grade of Automation 4 (GoA4) operations.

Metro de Madrid’s automation project of Line 6

This study considers the current status of automation projects across the group, and how metros prepare for operating automated systems. It compiles experiences of new lines and brownfield system and sub-system upgrades, covering integration and interface management, platform doors and passenger safety infrastructure, staffing, emergency management, pre-operations, and operations strategies.

The report brings together information provided by COMET metros and selected ISBeRG railways through a questionnaire and in-depth discussions, including at the Metro Automation expert workshop held in Madrid in March 2025.

Research: Non-Fare Revenue

Non-fare revenue has become even more important due to the steep decline in metro ridership and fare revenue related to the pandemic and subsequent economic downturn. Given the uncertain financial situation, COMET members have shown growing interest in topics related to funding and revenue.

The study explores the changes in non-fare revenue generation amongst COMET metros, in a post-pandemic world of financial uncertainties. It covers contextual information including organisational structures for non-fare revenue generation, along with details including targets, long-term plans, and strategic approaches. It delves into the categories of non-fare revenue in the COMET KPI ecosystem including advertising, retail, telecommunications, and other sources. Good practices and lessons learned by COMET members are highlighted for each of these categories.

Example of non-fare revenue: Berlin BVG U-Bahn Subway Tour

Research: Real-Time Monitoring of Track Equipment

Real-time track monitoring is a technology that offers continuous monitoring and quick detection of defects, enabling better preventative maintenance, and allowing for more effective trend analysis of precursors, incidents, and high-risk areas.

The study explores how COMET members utilise real-time monitoring technologies for track equipment. It sheds light on the monitoring of four components of track equipment: tracks, rails, power systems, and switches and crossings machines.

The research highlights the technologies in use for monitoring these assets and examines the challenges faced and the best practices to enhance monitoring accuracy.

Research: Reducing Impact of Major Projects

Delivering major projects while maintaining reliable metro service is a critical challenge for metro operators. These projects often demand extensive resources and long-term planning, which can strain organisational capacity and divert attention from day-to-day operations. As a result, metros must carefully manage the impacts of major project works on service reliability, financial sustainability, and the overall customer experience.

The study explores how metros can plan and deliver major infrastructure projects while minimising disruption to operations, staff, and budgets. It draws on lessons from both past and planned major projects across COMET metros. It examines how metros plan and coordinate major projects and maintain service continuity during delivery. It also explores how metros assess and communicate the impacts of major works on performance and customer satisfaction.

Example of communication for major projects: Atlanta MARTA Airport Station closure outreach

Research: Employee Satisfaction

Keeping metro staff satisfied is essential to the successful operation of metro systems. Metros face the unique challenge of managing a diverse range of job roles, both operational and office-based, which shapes staff expectations and the types of employee satisfaction initiatives that are possible.

The research provides an overview of employee satisfaction initiatives that were successfully conducted by metros, exploring approaches for improving collaboration and communication within metro organisations. It also provides an update on the status of flexible working options that are offered by metros as well as good practices to engage newer and younger employees.

Examples of employee satisfaction initiatives

Research: Performance of New Fleets

Rolling stock performance typically follows a ‘bathtub curve’ throughout a vehicle’s ~40-year lifecycle. This is characterised by higher rates of failures in the early stages due to design or assembly defects or staff unfamiliar with the equipment, which falls to a lower, relatively stable rate of failures during the normal operating period. We would then expect failure rates to increase again towards mid-life or end of life.

The study analyses rolling stock failure rates of individual vehicles within a metro fleet relative to their time in service, allowing members to compare the bathtub curve for new fleet failures across metros and within fleets.

Factors impacting failure rates of new fleets

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