In January 2025, a train entered service in Qingdao, China, that had more in common with a commercial aircraft than any metro carriage before it. The same supplier making composite panels for Chinese jets helped build its body. And it's made by the same company now delivering trains to Bengaluru.
Carbon fibre was the material of racing cars and military jets. Then it became the skeleton of commercial aircraft — the Boeing 787's fuselage is 50% carbon fibre by weight, the Airbus A350's is 53%. Both aircraft crossed into service in the 2010s and changed what long-range flying costs to operate.
On January 10, 2025, carbon fibre crossed another gap — onto a metro platform in Qingdao, eastern China.
What the CETROVO 1.0 actually is
CRRC's CETROVO 1.0 — officially the Carbon Star Express, or 碳星快轨 — is the world's first metro train whose primary load-bearing structures are built from carbon fibre composite materials. Not just interior panels or trim. The car body shell itself, the bogie frames (the wheel-and-suspension assemblies under each car), the driver's cab, and the equipment cabinets are all CFRP: carbon fibre reinforced polymer.
The result in numbers: the car body is 25% lighter than a conventional aluminium equivalent. The bogie — historically a forged steel assembly weighing several tonnes — is 50% lighter. Overall, each six-car trainset is 11% lighter than a conventional metro train. That translates to 7% less electricity per journey and approximately 130 metric tonnes of CO2 saved per trainset per year.
The CETROVO 1.0 entered revenue service on Qingdao Metro Line 1 — 37 km, 41 stations, in the coastal city of 10 million where CRRC Qingdao Sifang (the manufacturer) is also headquartered. The project took seven years from concept to service: CRRC unveiled the original CETROVO prototype at InnoTrans Berlin in September 2018, then spent the next six years solving the manufacturing problem.
The manufacturing problem
Making aircraft carbon fibre is slow. Each component is typically cured in an autoclave — a pressure oven the size of a small building — at high temperature and pressure. That works for commercial aircraft: you make a few hundred a year. Metro trains need thousands of cars produced at factory pace.
The solution came from an unlikely direction: pultrusion. It is a process previously used for items like window frames and ladder rungs — you continuously pull fibre reinforcement through a resin bath and a heated die to produce a constant cross-section structural profile. Fast, repeatable, and capable of industrial volume.
CRRC's engineers, working with CG Rail GmbH and researchers at Technische Universität Dresden, adapted pultrusion to produce CFRP profiles with wall thicknesses up to 25 mm — strong enough to transfer longitudinal forces of 1,200 kN and absorb the bending loads of a loaded metro car at speed. The composites were supplied by AVIC Composite, which is part of China's state aerospace group — the same supplier making composite components for COMAC commercial aircraft and Chinese military jets.
The Namma Metro connection
The trains currently being commissioned on Bengaluru Metro's Green Line (Phase 2) are also made by CRRC — 21 six-car trainsets under a contract signed in December 2019, first unit delivered to Bengaluru in January 2025, the same month CETROVO 1.0 entered service in Qingdao.
India does not yet have a metro system that has ordered carbon fibre rolling stock. The economics, however, point in one direction. Lighter trains use less energy per passenger-kilometre, require smaller power substations, cause less wear on tracks and civil structures, and — through CRRC's SmartCare digital maintenance platform — cost an estimated 22% less to maintain over a lifecycle. In a country building 20-plus metro systems simultaneously, those multipliers matter.
Carbon fibre metro is not a question of whether the technology is proven. It ran its first paying passengers in January 2025. The question for the next Indian metro rolling stock tender — wherever it is — is what specifications get written, and whether the engineers writing them have been to Qingdao.
Sources
- CRRC CETROVO 1.0 begins commercial operation (CRRC official)
- CETROVO 1.0 metro train starts operation in Qingdao (Xinhua)
- CRRC launches first metro train made of carbon fiber (Railway Pro)
- Carbon fibre metro trainset to enter service (Railway Gazette)
- CETROVO 1.0 metro train has begun commercial operation (CompositesWorld)
- Carbon-fibre-intensive CETROVO subway train launched in Qingdao (JEC Composites)