The electrification of railways continues around the world, but older systems also require maintenance and renewals as the years advance. Writes Peter Stanton
The costs of fixed installations on electrified railways can be very significant and much debate occurs over the capital cost of new works. However, the systems can have a significantly long life and much of a system can be refurbished or overhauled to bring performance up to required standards.
Supply voltages may change and the advent of Technical Specifications for Interoperability may also drive a requirement to change configuration. In the extreme the older systems, often pre-second world war, may require total replacement – even including the support structures.
The challenge is to come up with the best whole life costs and a recent congress on Whole Life Cost Optimisation in London centred on this very subject. The congress is an annual rail electrification meeting, hosting infrastructure managers to share lessons from construction, maintenance and renewals electrification projects. Its aims were to discuss cost-benefit analysis on latest technological advances and to increase the performance, reliability and efficiency of overhead line and power distribution systems. Vital to the process is assessing the optimal balance for maintenance versus renewals, perhaps spending more today in order to save on costs over the long term.
The presenters were drawn from a wide range of railway authorities worldwide, sharing their experiences of electrification management and engineering and of completing works with the minimum disruption to traffic. European terminology was the order of the day and in particular one had to become used to the system being OCS (Overhead Contact System) and what the UK describes as the catenary wire being the ‘messenger wire’.
The view from the top
Governments are commonly involved with major transport infrastructure works and therefore have a significant interest in the costs thereof. A national policy should look at the whole life costs although national governments may often be constrained within election periods.
The UK position was put forward very clearly by Paul Fishwick, principal sponsor – road and rail projects with the Department for Transport. The scene was therefore set with a statement of commitment to a rolling programme that would support economic growth, achieve best value, boosts the skills base and provide clarity for the supply market. This was set against a timeline running from 2013 to the announcement of plans for control period six in 2017.
It was refreshing to hear a view that the government has a long term view and was therefore funding line speed improvements, supporting Network Rail’s proposals for asset renewal and simplification and funding major remodelling while seeking other funding resources such as European institutions. Further optimisation of proposals were integrated with support for big ticket items such as power feeds and high output plant, securing determination funding for ancillary works and ensuring that infrastructure operator customers are involved in scope, design and development.
Ramping up in the UK
Whilst the conference was truly international, the project scene was first set for the UK by Network Rail’s Nick Elliot, southern regional director, who gave an overview of the newly formed Infrastructure Projects business which is divided into four regions. Nick is taking the lead on electrification, so he presented the challenges of control period 5 when Network Rail will move from electrifying 20km of track per annum to in excess of 1000km per annum. This will increase the proportion of electrified lines from 40% of the network to 51% – an increase of 3,000 single track kilometres.
The main challenge will be the ramping up of spend and the capacity of industry to meet the increased production. Coupled with that
is the focus on standards and specifications. For the UK this leads to considerations of speed capabilities, compliance with European Technical Specifications for Interoperability (TSIs), new system designs and traction power strategies.
Further insight into the UK experience was given by Jeff Davies, route asset manager (electrification and plant) for Network Rail Great Western, followed later by a point of view from the route asset management director, Mike Gallop.
The presentation centred on effectively increasing the reliability of OCS to reduce delays through design. Asset management is a way of thinking and behaving, and significant investments in new electrification should be made with a philosophy of ‘future- proofing’ assets driven by whole life cost decisions. The system is viewed with a traction power strategy and major feeding design – the application, on Great Western, of series 1 OCS and route clearance issues. Traction supply modelling is based on a view of the demand well ahead.
The new OCS design was chosen after considering existing UK designs and European systems straight off the shelf. Certain principal design requirements were applied, including:
- Meeting future capability / capacity as per the Route Utilisation Study;
- TSI compliant with multiple pantographs at speeds of up to 140mph;
- Compatibility with existing and proposed UK electric traction; » Improved safety and reliability with less maintenance;
- Adaptable for ‘classic’ and AT power supply feeding systems; » Operating at 12kA fault levels; » Compatible with both ‘high Output’ and conventional construction methods;
- Faster installation times;
- Designed for W6a, W9, W10, W12 and UK1 gauges;
- Mechanically independent wire runs with no tail wires – anchors above each track.
Whole life cost inputs were usefully defined at this stage as including both design costs and component quantities and cost, the cost of incidents including labour and disruption, and any renewals and enhancements.
The validation of the system will be undertaken on the UK test installation at Old Dalby. This will allow full acceptance of the new OLE design and also testing of the new IEP train away from operating Network Rail infrastructure.
TSI compatibility of the new OCS was examined by Andy Mackintosh of Network Rail. Where the power supply is designed to TSI voltage limits, pantograph head profiles are compatible and rolling stock configurations (dynamic OCS/ pantograph performance) also achieve compatibility. However, in the area of rolling stock gauge and contact wire heights, UK special conditions are applied.
The European view
A common theme of all the countries’ representatives taking part though was the realisation that for railway infrastructure, and electrification in particular, whole life cost was a major issue. The central European railways such as DB, ÖBB SNCB and SNCF placed major emphasis on this and proceeded to explain how they approached their task in the area of existing equipment.
The Belgian infrastructure organisation, INFRABEL, led off with a methodology for undertaking its OCS renewal policy. This looked at several options:-
- Partial or complete renewal instead of like-for-like occasional replacements;
- Replacement of contact wires after the passage of a number of pantographs;
- Regular monitoring with modern detection tools based on detailed scanning;
- Regular maintenance interventions only on critical points.
The general overview then looked at how the organisation took the analysis forward. Firstly a working group was set up which then looked at the failures of the OCS in terms of the most common reasons, the most common incidents and gathering details of the technical ‘top ten’. These were looked at in the light of the impact on punctuality and the direction to be taken with the maintenance policy.
In the case of the Belgian infrastructure the conclusions came out of acceptance that there was an ageing infrastructure and that there was a need for ambitious renewal projects and a proper life-cycle policy. Regarding maintenance, the view centred upon automatic instead of manual measurement, lower inspection frequencies and special actions to prevent incidents. There was also an acknowledgement that, in relation to total costs, materials were relatively insignificant in monetary terms.
The representatives of ÖBB then added an interesting dimension by presenting their definition of condition category – enabling a quantitative analysis of a system. In their case they referred to a study of the Bruck- Graz-Spiefield line. The five condition definitions are worth quoting as they can be applied to any system:
- Category 1. State of the system very good, no limitations.
- Category 2. State of the system good, no limitations. The system has small defects. For the longer term (>12 years) repairs required.
- Category 3. State of the system poor, no limitations. The system has gross defects. For the medium term (5-12 years) repairs required in the next few years.
- Category 4. State of the system very poor, no limitations. The system has gross defects. Repairs or renewal required in the next few (1-5 years) years.
- Category 5. State of the system very poor, limitations present. The system has gross defects. Repairs are not possible due to technical / economic reasons. Renewal of the system required within one year.
An option for infrastructure is life extension and this was tackled by the French delegates from RFF. This too looked at a real case study – the design for the ‘midi’ OCS introduced between 1920 and 1935 in the South West of France. This is a 1500V DC system which is viewed as a ‘cheap’ design with spans of over 90 metres and a maximum 100kph line speed. Modernisation was desired giving a higher performance corresponding to traffic and market needs.
The system was tackled in segments, the first concentration being on the structure base and foundation as corrosion occurs where water settles at the base of the mast and the assembly attachment points. The base was dealt with by protective paint and various options for reinforcing the mast. Options for the assemblies included replacement of the full assembly or just the registration arm and the steady arm.
Contact wire replacement is diagnostic based on automatic measurement supported by an IT tool. Solutions include the impact of reinforcement of the contact wire, replacement by alloy copper wire and the installation of an overlap in the case of a tension length regarded as too long. The view of the presenters was that life extension gives good results if it is managed as a whole system, taking into account access windows and the capacity of the industry to provide suitable components.
Returning to the UK scene, a major factor in maintenance and renewal is access to the railway. This thorny subject was tackled by Brian Sweeney of Network Rail Scotland in a thought-provoking item dealing with innovative practices for quick and efficient isolations that maintain safety levels. Brian summarised two solutions for better access that are currently being developed – taking thoughts back to first principles in managing risk, issuing permits and dealing with induced voltages.
With the amount of 25kV electrification across the UK network about to increase considerably, the opportunity to introduce new technology and processes needs to be taken to look at reducing this element of whole life cost without reducing safety levels. Industry pressure drives increased train services resulting in a reduction in engineering access while, at the same time, regulations and safety philosophy heavily influence process assembly.
The time taken to attain isolation has been carefully analysed and the average calculated to be 83.5 minutes. This considerable loss of potential working time could be tackled with innovations such as the remote application of earths, which will also avoid the need to walk along track in the dark. Simplified switching could be enjoyed by the electrical control operator although major gains could come from tackling major changes to signalling and electrical control technology / policy.
Two potential solutions were presented which involved advancing IT involvement in isolation management and targeted to at least issue a permit in around 35 minutes rather than the 83.5 minutes currently calculated. The isolation philosophy was coupled to studies in introducing work methods such as ALO (Adjacent Line Open) which is a further work stream undertaken with Network Rail. This involves creating plant control measures in a more safety critical level than has been the case and plant hire companies are cooperating in developing the process.
Regulation 14 of the Electricity at Work Regulations was examined, with a view to the use of a limited permit which would be preferable to working adjacent to live equipment, especially if it is quick and easy to implement. Analysis of ‘safe’ voltages for access suggests that works could be considered where differing degrees of earthing could be applied. However, the summary conclusion was that working under a full isolation is always the preferred option.
The conference was rounded off nicely by a presentation from John McNaughton of Irish Rail, dealing with the condition of the “DART” suburban system around Dublin. John presented an interesting case study in how to retrieve shrinking performance and optimise maintenance to allow the efficient running of the system to be regained and held.
Overall, the conference gave a very thought provoking challenge as to how the industry should approach whole electrification life costing, giving support to the view that first cost calculations were not the answer. The industry should benefit from the studies that were put forward and assist the growth of electrified railways while optimising the cost of both new and refurbished systems.