London Underground Limited Research Articles

Behaviour of cast-iron bolted tunnels and their modelling

The behaviour of cast-iron bolted tunnels in London underground railway network was investigated using the 3-D finite element (FE) method. A series of numerical simulations on a cast-iron segmental ring were conducted and its performance was compared against the analytical assessment used by London Underground Limited (LUL). Unlike the 2D plane model used in the LUL standard, the proposed FE model considered the 3D lining structural features (i.e. the geometry of the tunnel segment and the bolted joint) in a detailed manner. The behaviour of a cast-iron tunnel primarily goes through three stages: tunnel construction, soil loading and structural deterioration. At each stage, the influences on the tunnel behaviour such as external loading, soil-tunnel interaction were examined. Considering that, the proposed model thus resulted in more realistically structural performance in agreement with the field measurements.

Northern Line tunnel reconstruction at Old Street

For many years, London Underground's Northern Line tunnels just south of Old Street station had suffered from attack by sulphuric acid. These tunnels were constructed between 1899 and 1901, and were enlarged between 1922 and 1924. Acid began to seep into the tunnels in 1945 and cracks appeared in the tunnel linings in 1960. Over the years, to ensure safety, London Underground Limited (LUL) monitored the increasing levels of distortion and cracking of the tunnel linings and installed temporary strengthening until the need for innovative long-term solutions became evident. This paper describes various investigations into the problem, the formation of a solution and the consequent construction works, which had to be carried out with minimal disruption to services within the complex operating environment of the two Northern Line branches. The solution was to replace the grey cast-iron linings with larger diameter acid resistant linings made from cast duplex stainless steel. The works were carried out at night using a special shield, through which the trains passed during the day. The project took six years from initial concept to completion, including more than four years of research and design, a precasting contract for the linings and finally nine months of installation works. In total, the project cost approximately £15 million.

Aiming for restructuring success at London Underground

AbstractBeginning in 1997, the UK government called on London Underground Limited (LUL) to assess its options for a broad restructuring. LUL commissioned an analysis by PA Consulting Group featuring the development and use of a system dynamics simulation model of the Underground. This article describes major aspects of this work, and how use of the dynamic simulation model has evolved to meet LUL's changing needs. The model provided a common framework for analyzing structural options; simulated performance under different potential structures and identified critical aspects of implementation; helped educate LUL's potential private‐sector partners about the Underground; and, most recently, enhanced LUL's evaluation of the private sector bids. Copyright © 2001 John Wiley & Sons, Ltd.

The Northern Line train service contract

The involvement of the private sector in the funding of large-scale public sector projects has become a feature of Government policy within the United Kingdom. The first such initiative within the railway field has been the usage contract placed by London Underground Limited (LUL) with the ALSTOM Transport Sector. The implementation and operation of this very large contract could well become a model for future projects.

The Application Of Systems Engineering Tools OnLondon Underground

This paper reports on the application of systems engineering tools, either used or developed by the Systems Engineering Team of Trains Delivery Group, supporting all areas of London Underground Limited (LUL). It focuses on three Major Projects which have applied them to varying degrees. Central and Northern Line Projects have made use of a suite of simulators developed in-house to gain early understanding of system issues such as power supply and demand, signalling capability and possible levels of train service. Jubilee Line Extension Project have made use of tool to support requirements management. It concludes that benefits to LUL has been demonstrated by the application of these tools.

Maintenance depot transformation, not just a face-lift

London Underground Limited (LUL) has awarded GEC ALSTHOM (GECA) a service provision contract to provide and maintain 106 new trains under a leasing agreement for the next 20 years. The service will be provided to the Northern Line, with LUL retaining responsibility for operational control. Maintenance will be performed in the existing Northern Line facilities and the depots will be leased from LUL to GECA for the contract period. The maintenance depots require modernization to support the new trains and GECA Railway Maintenance Services Limited (RML) will manage and operate the depots. RML is now responsible for delivering the existing trains to the Northern Line and for introducing the new fleet of trains while the maintenance facilities are modernized. This paper addresses the modifications made to the maintenance facilities for the new fleet of trains. It discusses the philosophy behind the redesign of the depot layout, the steps throughout construction and the maintenance equipment necessary to provide the service required to meet the needs of the customer.

Railway profitability and station closures

At present there is considerable debate on railway ownership, with privatizations occurring in a number of countries. Against this background, the management of London Underground Limited (LUL) wished to understand the likely behaviours of possible future owners, particularly any following a strategy of profit maximization. This paper is concerned with the network or geographical implications of any such strategy. Two elements of the network were examined — first, branch termini, and secondly, surburban stations on core routes. Although one might wish to close branch termini, operational reasons such as the location of depots prevent this in some cases, but analysis was carried out for the remainder. Poorly-used suburban stations were also examined; a simplified linear programming approach was used to identify those stations where traffic levels were insufficient to cover operating costs and the disbenefits to through passengers. These calculations were carried out for a number of scenarios, including short- and long-term, and benefit maximization and profit maximization. Although much of the network is sustainable in the short term, or under benefit maximizing conditions, it was shown that only around half of it is financially profitable in the long term.

Interaction of vegetation with the LUL surface railway system: M. J. Gellatley, B. T. McGinnity, D. H. Barker & W. J. Rankin, in: Vegetation and slopes: stabilisation, protection and ecology. Proc. conference, Oxford, 1994, ed. D.H. Barker, (Thomas Telford, for ICE), 1995, pp 60–71

The London Underground Limited (LUL) public transportation system comprises some 400 route kilometres of track with just in excess of half of this forming the surface section of the system. Vegetation performs an important engineering function on the surface railway in providing shelter from the effects of wind and snow, in maintaining and enhancing the stability of earthwork slopes and in providing visual and acoustic screening. Vegetation growth also has important implications for the local ecology and wider environment. This has been recognised and recently LUL have taken steps towards defining and implementing integrated vegetation management standards. This paper provides an assessment of the interaction of vegetation with LUL earthworks slopes and structures within the surface railway corridor and reports on current vegetation maintenance standards and strategies. For the covering abstract see ITRD E116612.

A New Method Of DC Power Supply Modelling For Rapid Transit Railway System Simulation

The Multi-Train Simulator (MTS) originally developed by the University of Birmingham more than 20 years ago, with an investment in excess of 30 person years, was purchased by London Underground Limited (LUL) in 1989 [1, 2, 3]. The MTS is capable of modelling all the major electrical and mechanical subsystems on rapid transit railways including power supply, rolling stock, signalling and control systems and the interactions between these systems. Therefore, the MTS has been extensively used as a main design tool on mega engineering projects such as the Central Line modernisation project and the Jubilee Line Extension project. At the same time, a multi-stage development programme has been initiated to further develop the MTS to become an integrated railway simulation package encompassing all railway aspects. One of the important areas of the development programme was to review the existing power network solving technique and its suitability for multi-track network with interconnection between all tracks. This was with a view to develop a more versatile power network solution technique which will result in savings in computation time and memory storage. This work can form the foundation for future plans of providing real-time monitoring and control facility using what-if predictive simulation adopting parallel computing techniques.

Optimised Planning Of Railway Investment

London Underground Limited has a major programme of capital investment to improve service quality and financial performance and to provide wider social benefits. This programme has to be planned within strict but fluctuating funding limits. Traditional investment selection and planning techniques have to date been employed with great difficulty. An innovative approach, called Portfolio Optimisation, is being implemented, which shows great potential for improving the business planning process. This paper describes the concepts underlying the approach and the supporting computerised modelling processes. Maximising investment benefits London Underground Limited (LUL) operates one of the largest metropolitan public railways in the world. Capital investment varies between £500 million and £700 million per year, depending upon the level of government grant. Annual operating expenditure is of the same order. There are, however, insufficient funds to perform all of the required improvements needed for the network. There is therefore a critical need to identify those investments, within the funding limit, that will yield the greatest benefits to the system. This will help to achieve the desired standard, termed Decently Modern Metro (DMM), as soon as funds allow. Transactions on the Built Environment vol 6, © 1994 WIT Press, www.witpress.com, ISSN 1743-3509 94 Railway Design and Management