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Saturday, April 4, 2020

Heathrow Express control solution

Launched in 1998, Heathrow Express is the fastest means of travelling between the airport and central London, with 150 trains carrying an average of 16,000 passengers every day to and from Paddington Station. Over 60 million people have used the service since it started, taking just 15 minutes to reach Terminals 1 & 3, 23 minutes to Terminal 4 and 21 minutes to Terminal 5.

The train operator has adopted a forward-looking approach to the handling, reporting and delivery of information to both passengers and its staff – this encompasses data relating to timetables, operations, safety protocols and procedures as well as general station information.

Meeting the challenge

When its existing control infrastructure started to suffer from obsolescence, patchy support and unacceptable reliability, Heathrow Express turned to technology from Rockwell Automation specified by Firstco, a technical engineering consultant specialising in controls and communication systems for the transport, building and process industries. Firstco was tasked with specifying and sourcing a contemporary solution to the operator’s control needs.

The criteria were decided upon right from the outset. “We required a scalable solution for managing the information from and control of our safety, security and other monitoring sub-systems” says Keith Harding, Heathrow Express’ Operations Director. “We also needed ongoing flexibility so once we had successfully migrated to our new system we could continue to develop and adapt to include evolving technologies.”

As consultant, Firstco’s initial task was to gather all of Heathrow Express’ technical requirements, draft a user specification and then put it out to tender. Director Bill Martin asserts that “The control solution had to encompass a number of facets including CCTV, PA, ventilation, safety scenarios, lighting and information boards – all of which had to feed back into the central control room.”

“The open and scalable elements of the specification immediately discounted the use of proprietary black-box solutions that are rife in the rail industry” he recalls. “Instead we determined that an open, off-the shelf system was the most appropriate solution and began sourcing potential suppliers. The project was managed in-house by Heathrow Express and we were asked to design the system from the high-level requirements, through the installation, management and operations to commissioning and supplying all the SCADA (supervisory control and data acquisition) and PLC (programmable logic controller) systems.”

Heathrow Express operator
Each operator can control and monitor all sub-systems on one fully integrated workstation

The way forward

Firstco’s role in the project grew steadily and, in 2003, it recommended the complete replacement of the bespoke/closed incumbent SCADA solution which was proving difficult to maintain and update, as well as being inflexible to Heathrow Express’ needs. Investigations lead to a solution based on RSView 32 from Rockwell Software.

In 2004, Heathrow Express asked Firstco to take over the ongoing maintenance and supply of all systems including telephony and data. Very soon the project demonstrated its need to be scalable and moveable when the company was also asked to develop the control and communications infrastructure for Terminal 5’s station expansion.

Heathrow’s existing network used Allen-Bradley SLC PLCs for monitoring the utilities. Firstco was able to change the interfaces to other systems to a Rockwell Automation interface which allowed the infrastructure to ‘talk’ to all sub-systems, removing the reliance on the older black-box-based solution.

The complete T5 station and tunnel SCADA solution, based on Allen-Bradley ControlLogix PACs (programmable automation controller), comprises six sub-systems – fire monitoring, tunnel ventilation (to SIL2), the public address system, train information displays, CCTV and utilities, including all equipment, faults, doors and access control. According to Martin, “The PAC network uses in excess of 10km of dual-redundancy cabling – both copper and fibre – to connect 23 ControlLogix PACs on a ControlNet network. Of the PLCs, 18 are configured as hot-standby, fully redundant pairs and are SIL2 compliant.”

“The PACs are networked to 49 purpose-built remote I/O control panels giving connection to approximately 2,400 digital and analogue I/O points”, he continues. “In addition to the hardwired inputs, the system also has seven different protocol interfaces allowing control room staff to seamlessly manage the various third-party systems. A redundant server/client RSView 32 SCADA system brings all the systems together to provide a fully integrated user interface. The additional control and monitoring required for the new T5 systems have been engineered into the existing graphical user interfaces to help make sure the entire network, now comprising 59 PACs, appears and operates as one single integrated system to the operators.”

More of the same

The design for the new control room had to be flexible, maintainable and, above all, future-proof, ready for the integration of the new Terminal 5 station. The three-position control room – operations, services and break relief/incident management – allows each operator to have full control and monitoring of all sub-systems on one fully integrated workstation.

“We used standard SCADA because it is easily maintainable and modifiable”, explains Martin. “What’s more, it can be done by other parties, unlike black-box solutions which often tie you to the original supplier. What we have done is break the black-box monopoly.”

“When T5 came along, with the same remit as the original upgrade, we worked very hard with Rockwell Automation to deliver a system that the staff at Heathrow Express liked and took pride in”, Martin explains. “The staff there were heavily involved in the upgrade project and simply said ‘more of the same please’ when it came to T5. The major difference between T5 and the original system was the requirement for a SIL2 solution for the tunnel ventilation and we were already in a good position thanks to Rockwell Automation’s ability to supply SIL2-capable equipment. In fact we think this may well now be one of the biggest SIL2 PLC networks in the world with over 60 dual redundancy ControlLogix PACs.”

By putting all the control systems in a single Ethernet/IP and ControlNet architecture, there is a high level of integration between the sub-systems. This means that they ‘listen’ to each other’s relative status and offer the controllers quicker reactions to issues – that’s especially important due to the requirement of the station’s ‘six-minute/no-action’ evacuation protocol. The security systems are also integrated to CCTV and the arrivals schedule is tightly linked to the lift controllers, meaning that elevators are waiting at the right level when trains arrive.

Heathrow Express Firstco maintenance
Firstco maintains and supplies all systems including telephony and data

Reliable and dependable

The 2003 upgrade and subsequent T5 expansion have met all reliability and maintainability targets. Keith Harding explains that “Over the last few years we have seen 99% reliability of all systems due in part to the dependability and reliability of the infrastructure supplied by Rockwell Automation through Firstco. The opening of T5 increased traffic by some 14% and achieved the highest reliability rate, irrespective of T5’s well-publicised teething problems.”

“Firstco is an independent consultancy and has a wealth of potential suppliers at its fingertips” concludes Martin. “However, we often find that Rockwell Automation is one of the obvious choices for a lot of our work because of the flexibility it allows us to offer our customers. I think it is safe to say that the reign of the black-box is now over. With off-the-shelf solutions offering this type of capability, it is hard to see a future for bespoke, closed and proprietary control solutions.”


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