The Challenges of Rolling Stock Projects

Rolling stock are complex integrated systems within the railway system. When they require enhancement, other than maintenance and painting, this can result in complex programmes of work. As well as the on-board systems including doors, traction/braking, on-board communications systems, toilets and air-conditioning, rolling stock requires interoperation with infrastructure systems such as signalling, platform systems and network communications systems. All these systems have a level of safety integrity that should be considered, designed for and tested accordingly. This level of complexity requires effective programme management to ensure the expected benefits are realised, safety is maintained and interoperability with the whole railway system is retained. For introduction, refurbishment or replacement programmes, the unique qualities of rolling stock bring added complexities:

• The railway system remains operational. When an infrastructure renewal or enhancement is required, a possession is often required, resulting in a temporary service reduction or even suspension. Rolling stock vehicles can be taken out of service whilst retaining a service level. However, this results in a compromise needing to be reached between the available trains for service, the timescales to roll-out across the fleet and the efficiency of the production line facilities.
  
  
• Interoperation of new and previous rolling stock fleets. Due to this roll-out programme, as soon as the first vehicle is converted, the railway must temporarily operate with two rolling stock configurations until all vehicles are converted. This migration phase duration can be up to several years, having a significant impact on operations, maintenance and the passenger, all of which require appropriate mitigation. 
  
  
• Multiple rolling stock configurations. A single rolling stock fleet can have driving motor vehicles (with a driving cab and propulsion equipment), non-driving motor vehicles and trailing vehicles, as well as wheelchair-accessible, first class and catering vehicles. Indeed, there can be variations even within a configuration: build tolerances across a fleet, depending on how/when they were manufactured, can be found not to conform to drawing. For each vehicle, a different design may be required, each of which need verification and validation. Overlaying different systems results in several permutations of design and can require a significant level of configuration control.
  
  
• Significant testing requirements. The new rolling stock requires testing in two stages: testing against an infrastructure reference as required by standards, and then on the operational railway to validate against its specific qualities (gradients, gauging, horizontal and vertical curves, power supply, electromagnetic context) and interoperate with the existing systems: signalling, platform based doors/gates, correct-side door opening and more. The complexity of validating these interfaces makes it cost effective to produce and test a first-off train before commencing series production, bringing about challenges in the production line and supply chain. On top of this are the inevitable modification and/or fixes for things that do not work properly. These design modifications and software updates require verification and validation before further roll-out, adding cost, delay and additional configuration control.
  
  
• Complex array of interfaces. Rolling stock systems are varied in their function, their required integrity level and the medium or method of controlling functionality. Systems can function using data, hard wire control, pneumatics, and mechanical methods; they can have safety critical functions, like braking and door closure, or less critical functions like displaying the destination. These systems often interoperate requiring detailed physical and functional interface management to ensure correct operation.

The resulting complexity means that managing the integration of rolling stock projects into an existing railway system is critical. The resultant risks can be effectively mitigated through introduction of systems engineering techniques such as requirements management, interface management, configuration control, engineering change control processes, programme level technical risk management. These techniques were used effectively at Transport for London (TfL) in the following Central Line case study. Zoë Dobell discusses her experience as a systems engineer within TfL prior to joining WSP, conducting the integration of the Central Line Improvement Programme. She discusses the complexity of the programme and the most pertinent systems integration techniques—outlining the benefits they provided for the railway system—and concludes with a look at how WSP’s SI:D³ can be used across other rolling stock programmes.

Case Study: Central Line Improvement Programme

The Central Line Improvement Programme (CLIP) is a rolling stock enhancement programme to improve various rolling stock systems on the 85-train fleet. The programme consists of six projects affecting the following train-borne systems:

• AC traction – to remove the existing DC traction system, most of which is underframe mounted and replace with an AC traction system (eight traction packages and 32 motors per train) 
  
  

• Data Transmission System (DTS) – to replace the existing train management system known as DTS. This involved cab and saloon equipment, with substantial saloon car wiring and some underframe wiring. This project re-used the existing train backbone wiring and improved connectivity between train-borne systems by providing a vehicle-level ethernet network, maintaining the interface with the equipment it controls and/or monitors.
  
  

• Passenger Information System (PIS) – to replace existing audio-only PIS and replace this and the cab front display with the addition of saloon displays. This system has a significant interface with the DTS. 
  
  

• Saloon CCTV – the introduction of a saloon CCTV system. This system has interfaces with DTS and PIS.
  
  

• LED lighting – to remove the existing fluorescent lighting system and introduce a new LED lighting system.
  
  

• Saloon Design – to re-design saloon panelling, bracketry and fittings to install all cab and saloon systems, as well as provide wheelchair spaces, improved flooring and repair floor corrosion