Acorn; Acorn;

Acorn, New York

A train control system for the digital age

The Autonomous Car Operating Rail Network (Acorn) is the next-generation in train control systems. Arup’s pioneering virtual system architecture brings communications based train controls (CBTC) into the digital age to dramatically reduce the costs associated with installation and maintenance, and achieve new standards in efficiency.

Leveraging proven technologies, Acorn provides the same IEEE controls as conventional CBTC systems, while substantially reducing infrastructure requirements. Acorn’s virtual distribution model improves system performance by making trains more responsive to real time route conditions. It also enhances cyber security and makes trackside implementation simpler.

The benefits of the Acorn train control system include:

  • User-friendly Interface: A digitally-rich cab designed with drivers in mind.

  • Performance Optimization: RFID tags provide steady stream of data to help keep systems running smoothly.

  • Superior Connectivity: Frequent updates between trains and the route control center (RCC) allow trains to quickly respond to real time route conditions.

Acorn harnesses RFID tag technology to improve communications-based train control (CBTC).
  • Safer, Easier Installation: Minimal trackside infrastructure expedites implementation and promotes trackside safety.

  • Enhanced Cyber Security: Multi-vendor sourced system architecture guards against common mode failures.

  • Compatibility: Overlay design allows Acorn to work in tandem with existing signaling systems or to stand alone.

How it works

Acorn leverages a range of technologies, including ARM CPUs (ARM), Bluetooth/Wifi, and RFID tags, to deliver a train control system that is smarter, more efficient, and more cost-effective than standard CBTC. The linchpin of the system is the Acorn Tag—a weather-proof RFID tag installed at regular intervals along the track, replacing much of the infrastructure associated with conventional CBTC systems.

Each time a train passes over an Acorn Tag, its onboard ARM writes a host of performance data to the tag. At the same time, the train extracts information written to the tag by the train ahead of it. This data can be used to determine the leader train’s location so that the system can continue to operate if communications between trains, or the trains and the RCC, drop out. 

Acorn’s pioneering block tagging system provides train operators with continuously updated information, allowing them to quickly adjust to real time conditions and minimizing unnecessary interruptions to service.

Substantial cost savings

Getting a traditional CBTC system up and running typically costs $12-30m per mile. Acorn can be implemented for $5m per mile, thanks to vastly reduced trackside infrastructure requirements. (Please note: costs will vary depending on the ratio of fleet size to track mileage.)

Installation and maintenance made easy

Acorn’s trackside components are confined to the installation of Acorn tags at 25ft intervals along the tracks, and trackside maintenance is limited to the replacement of Acorn Tags every 3-4 years. Moreover, the system was designed to ensure that software updates occur “in the background” without any discernible disruptions in service.

By harnessing the power of proven technologies, Acorn virtualizes CBTC functions across the entire rail network. The virtual distribution model not only improves system availability to support autonomous train operation, it also dramatically reduces trackside infrastructure requirements, thereby cutting the cost and labour associated with the installation and maintenance of conventional CBTC systems. ”

Ken Garmson Arup Ken Garmson Rail Systems, IT & Communications

Providing a safer system

The installation of standard CBTC systems requires extensive trackside work. Acorn’s virtual distribution model eliminates many of conventional CBTC’s trackside components, like the wayside controller, thus promoting safety. Acorn’s advanced system architecture allows clients to achieve a level of cyber security not easily reached by standard train controls systems. The system’s components and software are sourced from multiple vendors, thereby limiting the risk of a vendor hack revealing system-wide vulnerabilities. If one component of the system is compromised, Acorn immediately isolates the affected software or hardware and alerts the driver.

Acorn was a finalist in the 2018 Metropolitan Transit Authority Genius Challenge and was funded by Arup Ventures, an internal initiative to foster the development of novel solutions to real world issues in the built environment. For more information, contact: [email protected].