Knorr-Bremse has entered the final phase of a comprehensive program to modernize the rail signaling system for the Massachusetts Bay Transportation Authority (MBTA), the public transit operator in the Boston area. The project covers the Red and Orange lines of the city’s metro and urban transit network.
Through its KB Signaling division, the company is equipping the MBTA infrastructure with AFTC5 (Audio Frequency Track Circuit) systems, a track circuit technology that enables train detection and the transmission of information essential for operational safety.
The program has been underway since 2019, and completion is scheduled for the end of 2026. The project value is in the lower three-digit EUR million range, according to Knorr-Bremse.
26 stations equipped by the end of 2026
By the end of 2026, KB Signaling will equip all 26 stations on the Red and Orange lines with AFTC5 systems. Progress is already visible across the network, where over 800 AFTC5 systems are in operation under real-world traffic conditions.
Knorr-Bremse claims that the software-based electronic architecture is transforming the day-to-day operation of urban rail networks by improving safety, reliability, and traffic flow.
“Around the world, rail networks are entering a new phase of digitalization and modernization, which opens up growth opportunities for advanced signaling technologies and trackside equipment,” said Dr. Nicolas Lange, a member of the Executive Board of Knorr-Bremse AG and globally responsible for the rail division.
He added that signaling and electronics are a central component of Knorr-Bremse’s strategy to become a leading systems partner for the entire rail ecosystem. “Projects like the one in Boston demonstrate how our technologies turn vision into reality and how we deliver complex programs with a clear focus on our customers’ needs,” said Nicolas Lange.
Modernization Without Disrupting Daily Operations
According to the company, the project in Boston demonstrates how complex signaling systems can be modernized without disrupting daily operations. AFTC5 technology is gradually replacing older equipment in the field with electronic and intelligent architectures.
“The modernization of Boston’s Red and Orange lines—which covers 26 stations and already exceeds 800 AFTC5 track circuits in operation—represents a major milestone and clearly demonstrates how complex signaling projects can be successfully delivered step by step while maintaining daily operations,” said Jeff Baker, CEO of KB Signaling.
He added that local engineering teams are supporting the MBTA to achieve safer, more reliable, and more efficient rail operations within a complex urban network.
How AFTC5 Technology Works
The AFTC5 system marks the transition from traditional solutions to a digital generation of signaling equipment. The technology transmits audio-frequency signals directly through the rails, enabling reliable train detection.
This type of system also supports the exchange of safety-critical information, including commands related to train speed. Thus, the operator can obtain more clearly defined train positions, confirmation of track clearance, and safe separation of trains in service.
For dense urban networks, such technologies are important because they enable safer and more efficient operations without requiring a complete replacement of the existing infrastructure.
The technology is also used in Los Angeles and Chicago
Knorr-Bremse notes that the AFTC5 electronic platform is also used in other major metropolitan areas in the United States, including Los Angeles and Chicago. In these cities, the technology is part of long-term transformation programs that are gradually replacing older, often analog, trackside equipment with modern electronic architectures.
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