North America Sees Gradual Shift in Rail Signalling

At Wayside Digitalisation Forum (WDF) in Vienna, Jonathan Hu and Richard Plokhaar, Senior Technical Directors at WSP, highlighted the diversity and complexity of signalling systems across the United States and Canada.

During a keynote speech, Plokhaar and Hu explored how legacy infrastructure, fragmented standards, and evolving communication technologies are shaping the continent’s signalling landscape.

Freight Dominance

Hu noted that around 90-95% of rail revenue in North America is generated by freight operations, and this economic reality influences signalling choices. Most mainline railways consequently still rely on conventional Centralised Traffic Control (CTC), while urban and airport systems are increasingly employing communications-based train control (CBTC).

Examples include long-running CBTC applications at San Francisco and Seattle-Tacoma airports, as well as newer pilot projects extending the technology into light rail and mixed-traffic environments. Hu observed that such projects demonstrate a growing interest in automation beyond traditional metro systems.

However, for freight routes, communication coverage remains a constraint. Plokhaar cautioned that in remote freight corridors, there are still significant areas without wireless connectivity. Satellite may therefore remain the only practical solution for some time.

Fragmented Systems

Following several high-profile rail accidents, the US Congress mandated the introduction of Positive Train Control (PTC) in 2008 across key routes. The technology, designed to prevent collisions, overspeed incidents, and misaligned switches, has been rolled out across about 58,000 miles of the national network, which spans 140,000 miles.

However, Hu acknowledged that implementation has been inconsistent. Amtrak, for instance, operates with three PTC variants across its network to ensure compatibility with host freight railways. This diversity creates interoperability challenges for operators and engineers when moving between systems.

Hu said:

Every operator has taken a slightly different approach—some rely on transponders, others on GPS. The result is a patchwork of systems that are not fully interoperable.

Plokhaar also noted legacy challenges that add to the diverse systems in operation. For example, at Toronto Union Station, an electromechanical interlocking system dating from 1932 remains in partial operation. Despite handling more than 250,000 passengers daily, modernisation has been delayed due to certification challenges and the complexity of replacing bespoke components that are no longer manufactured.

Towards Interoperability

Despite this continued fragmentation, efforts to harmonise signalling are not new. In the late 1990s, New York City Transit launched the Interoperable Train Control Specification (I2S), a framework allowing equipment from different suppliers to communicate safely within shared infrastructure. Siemens and Alcatel (now part of Alstom) collaborated to test this concept, which is now operational on the Queens Boulevard Line.

Hu noted that similar principles are being applied in San Francisco, where authorities are transitioning to a CBTC-based system integrated with 5G communication for enhanced reliability and reduced wayside hardware.

Developments in Canada

In Canada, discussions are underway about creating a national train control system that would reflect local operating conditions. Transport Canada is exploring an Enhanced Train Control (ETC) system for its Class 1 network, combining overspeed warnings with automatic train protection. This will include two levels of automation: Driver Advisory Systems (DAS) and Automatic Train Protection (ATP).

Additionally, for Canada’s high-speed rail project Alto, Hu noted that a European Train Control System (ETCS) would likely be implemented. Likewise, this system is also expected to be deployed in the US for Brightline West and California High-Speed Rail.

Despite the diversity of systems in operation, both speakers agreed that a gradual convergence is likely in both Canada and the US. Industry discussions around ‘PTC 2.0’ and shared digital standards are underway, supported by major suppliers and public agencies.

As such, events like WDF provide a vital platform for collaboration between operators, suppliers and policymakers. By sharing practical experience across regions, participants aim to shape a more coherent, interoperable future for rail signalling worldwide.