MERMEC
MERMEC is an Italian supplier of railway diagnostics, signalling, and asset management technology, headquartered in Monopoli, Puglia, and wholly controlled by the private holding company Angelo Holding.
The business began in 1970 as a mechanical workshop building agricultural equipment and moved into railway maintenance and diagnostics in the 1990s under the Pertosa family. Vito Pertosa, who led that shift, founded the holding company that owns the group today.
Core products for wheel and axle monitoring
MERMEC’s portfolio in this field rests on fixed wayside measurement systems that inspect trains as they pass, rather than on a single product line.
Thermographic scanning builds a thermal map of the passing train to identify hot axle boxes and overheating loads before they reach a tunnel. The system covers a temperature range of 80 to 600 °C at speeds up to 330 km/h.
Wheel profile and diameter measurement uses optical acquisition to capture flange height and width, rim thickness, flange gradient, hollow tread, wheel diameter and diameter differences, and back-to-back gauge at speeds up to 250 km/h. A separate out-of-roundness system measures deviation from a true circle between 40 and 300 km/h, resolving flat spots above 30 mm and polygonisation up to the 32nd order.
Surface defects are covered by W-INSPECT, which uses high-definition cameras and a dedicated lighting system to detect shelling, spalling, and flat spots on the running surface. It measures at speeds up to 30 km/h, which places it at depot and yard entrances rather than on open line. Ultrasonic inspection based on electromagnetic acoustic transducers detects surface flaws without a coupling medium.
Market position
These systems sit alongside track geometry, rail profile, catenary and tunnel measurement in a portfolio delivered both as fixed installations and on board the ROGER family of measurement vehicles. Wheel and axle monitoring is one line within that broader diagnostics offer rather than the core of the business.
Customers span mass transit, mainline, high-speed, and heavy-haul railways. By the company’s own account, MERMEC runs 36 offices and production sites worldwide, with products and services in use in around 60 countries.
The group moved further into signalling in 2024, when it acquired Hitachi Rail’s mainline signalling business in France and its signalling units in Germany and the UK — a divestment required as a condition of Hitachi’s takeover of Thales Ground Transportation Systems. Around 550 employees transferred with the business.
Current activity
On 14 May 2026, Siemens Mobility and Angelo Holding announced an agreement under which Siemens acquires MERMEC’s diagnostics and data analytics activities, its wayside signalling business in Italy, and its electrification and telecommunications activities. Closing is subject to customary conditions and expected by the end of calendar year 2026.
The parties have not disclosed the financial terms; reports ahead of the announcement put the valuation above EUR 1 billion. The businesses inside the perimeter employ around 1,700 people and generated revenue of approximately EUR 430 million in fiscal year 2025 — a figure specific to the divested activities, not to Angelo Holding as a whole.
Excluded from the sale are MERMEC’s holdings in AngelStar, its ERTMS onboard signalling joint venture with Stadler; Mont Saint Michel and its subsidiary Compagnie des Signaux; and MERMEC Deutschland. These are to be grouped into a new signalling company, Angel Signaling, retained by Angelo Holding with around 800 employees.
Until closing, MERMEC continues to operate under Angelo Holding’s control. The group also takes part in Europe’s Rail, the EU rail research partnership, including work on standardising infrastructure and rolling stock condition-monitoring data across national networks.
