Railway Alignment Research Articles

Quantitative assessment of direct and indirect landslide risk along transportation lines in southern India

Abstract. A quantitative approach for landslide risk assessment along transportation lines is presented and applied to a road and a railway alignment in the Nilgiri hills in southern India. The method allows estimating direct risk affecting the alignments, vehicles and people, and indirect risk resulting from the disruption of economic activities. The data required for the risk estimation were obtained from historical records. A total of 901 landslides were catalogued initiating from cut slopes along the railway and road alignment. The landslides were grouped into three magnitude classes based on the landslide type, volume, scar depth, run-out distance, etc and their probability of occurrence was obtained using frequency-volume distribution. Hazard, for a given return period, expressed as the number of landslides of a given magnitude class per kilometre of cut slopes, was obtained using Gumbel distribution and probability of landslide magnitude. In total 18 specific hazard scenarios were generated using the three magnitude classes and six return periods (1, 3, 5, 15, 25, and 50 years). The assessment of the vulnerability of the road and railway line was based on damage records whereas the vulnerability of different types of vehicles and people was subjectively assessed based on limited historic incidents. Direct specific loss for the alignments (railway line and road), vehicles (train, bus, lorry, car and motorbike) was expressed in monetary value (US$), and direct specific loss of life of commuters was expressed in annual probability of death. Indirect specific loss (US$) derived from the traffic interruption was evaluated considering alternative driving routes, and includes losses resulting from additional fuel consumption, additional travel cost, loss of income to the local business, and loss of revenue to the railway department. The results indicate that the total loss, including both direct and indirect loss, from 1 to 50 years return period, varies from US$ 90 840 to US$ 779 500 and the average annual total loss was estimated as US$ 35 000. The annual probability of a person most at risk travelling in a bus, lorry, car, motorbike and train is less than 10-4/annum in all the time periods considered. The detailed estimation of direct and indirect risk will facilitate developing landslide risk mitigation and management strategies for transportation lines in the study area.

GIS-Based Railway Route Selection for the Proposed Kenya-Sudan Railway: Case Study of Kitale-Kapenguria Section

This paper describes a procedure developed for automated railway feasibility analysis based on GIS and Multi-Criteria analysis. Good engineering railway alignment requirements are assessed and suitable factors and constraints for feasibility analysis derived. Relevant digital map layers are then prepared and reclassified to meet the factor and constraint requirements. The layers are weighted and combined giving rise to a cost layer. Combination of the source and cost layer generates CostDistance and CostDirection layers. These two layers are combined with the destination to automatically generate four alternative routes each constrained to pass through apriori selected locations along the corridor from which the most optimal one is selected. This study aptly demonstrates that GIS is an indispensable and efficient tool for use in railway route selection.

Comprehensive assessment method for environmental impact of railway based on geographic information system

By integrating the merits of the map overlay method and the geographic information system (GIS), a GIS based map overlay method was developed to analyze comprehensively the environmental vulnerability around railway and its impact on the environment, which is adapted for the comprehensive assessment of railway environmental impact and the optimization of railway alignments. The assessment process of the GIS based map overlay method was presented, which includes deciding the system structure and weights of assessment factors, making environmental vulnerability grade maps, and evaluating the alternative alignments comprehensively to obtain the best one. With the GIS functions of spatial analysis, such as overlay analysis and buffer analysis, and functions of handling attribute data, the GIS based map overlay method overcomes the shortcomings of the existing map overlay method and the conclusion is more reasonable. In the end, a detailed case study was illustrated to verify the efficiency of the method.

Tunnel alignment design for Circle Line, Stage 3, Singapore: dealing with a densely built-up urban environment and challenging ground conditions

Circle Line Stage 3 (CCL3) forms part of Singapore's enhanced Rapid Transit system and probably represents the most challenging section of underground railway lines designed so far in Singapore. The overall route alignment for CCL3 does not follow the major radial road easements but instead passes through highly built up areas comprising low rise housing and apartment block estates and crosses numerous other infrastructure. As a result of this, the tunnel alignment design had to deal with the inherent engineering difficulties associated with theses constraints which also included large numbers of existing piled structures, the extent of which is novel in Singapore. Alignment design was aimed at achieving the correct balance between four principal factors. The factors were firstly, the desire to provide the required ridership, secondly optimum railway geometry for operational purposes, thirdly, the constraints on tunnelling imposed by the existing ground conditions, impacts on existing infrastructure and the desire to avoid expensive construction methods and high risk underpinning wherever feasible. The fourth factor was that the alignment design sought to provide least impact on the public in terms of nuisance, safety and private land acquisition. The balance of these factors was paramount to the successful design of this project. The challenges of this project required the Client (Land Transport Authority) and their Designer (MWH and sub-consultants) to work closely and proactively in pursuing railway alignment options that called for major modifications to the envisaged alignment from the previous feasibility designs. The final design saw the elimination of one of the six stations and the original requirement for underpinning of 20 major structures reduced to one. Adopted tunnel construction methods were principally using face pressurised Tunnel Boring Machines, with limited cut and cover structures for track cross-overs and mined tunnels for cross-passages or temporary access. Ground conditions expected at tunnel horizon comprise Bukit Timah Granite Formation rock, soil and extensive mixed face conditions, Old Alluvium and Kallang Formation soils. The alignment design process involved the assessment of alignment options by using ground characterisation through investigation, study of existing structures and foundations, identification of obstacles to tunnelling and methods of advance, analysis of tunnelling effects on structures, design of mitigation works and railway considerations. Each option was tested in terms of impact on the general public, buildability and cost. State-of-the-art geotechnical analysis methods were used to investigate the behaviour of piled structures during tunnelling and the design of piled underpinning to low and high rise structures. Significant advantage was gained by adopting a Value Engineering approach and designing the alignment to pass beneath government buildings that were scheduled for refurbishment, allowing partial demolition and the extraction of the existing piles, which would have otherwise been in the path of the Tunnel Boring Machines, from the surface. A trial of these pile removal works was made prior to adopting the preferred pile extraction method. This paper discusses the engineering challenges faced, presents a methodology for finding the optimum design alignments and describes important aspects of the adopted alignment. (A). Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.

Planning, Design and Construction of KCRC Tsim Sha Tsui Extension Railway Tunnels

The planning, design and construction of the KCRC Tsim Sha Tsui Extension railway tunnels from Hung Hom to Tsim Sha Tsui is considered as one of the most challenging projects currently in Hong Kong. This paper covers the railway alignment options and the tight constraints, how major environmental and cultural impacts are minimised and the handling of objections. The paper describes the construction challenge of the tunnels contract in an urban tourist environment, such as temporary traffic management, lack of space and how the risks associated with sensitive structures and utilities are managed. It also details the extreme risk working over the Cross Harbour Tunnel and ingress of water with a cofferdam excavation 18 m deep and only 10 m from the harbour, all of which require the highest calibre of engineering techniques and judgment. The key environmental impacts and social issues are minimised and addressed in a pro-active manner, turning objections in public consultations to a win-win situation with hoteliers and building owners on their cooling mains. The project management of constructing the tunnel box in just two years, together with major variations keeping to the original track access date, is a challenge successfully delivered with the teamwork and partnering spirit among KCRC, OAP andGammon Skanska.

A computer system for surveying railway alignments in Hong Kong

This paper describes various engineering surveying operations in the construction and maintenance of railway tracks through the functional modules of a specifically designed computer software. This software designs for the main functions of alignment. setting-out. as-built and right-of-way surveys. The software introduced is the RTS (Rail Transit Survey) ®. which has been used in railway projects by many international civil engineering contractors and railway corporations around the world.

A Computer System for Surveying Railway Alignments in Hong Kong

This paper describes various engineering surveying operations in the construction and maintenance of railway tracks through the functional modules of a specifically designed computer software. This software designs for the main functions of alignment. setting-out. as-built and right-of-way surveys. The software introduced is the RTS (Rail Transit Survey) ®. which has been used in railway projects by many international civil engineering contractors and railway corporations around the world.

Synergistic use of orbital satellite image and ground-based information in environmental monitoring of railway alignment construction - a case study

Environmental monitoring of road/railway/highway alignment construction activity is necessary to assess the probable negative impacts on the physical, biological and hydrological environment. This would aid in assessing the effectiveness of mitigation measures proposed and executed measures. Multitemporal orbital remote sensing data along with site-based information on water and air quality and noise level were used in the environmental impact assessment (EIA) and auditing of Konkan railway alignment in India. This method of integrated data collection and analysis could be used effectively for monitoring similar projects elsewhere.

A Three-dimensional Optimization Model for Railway Alignment Design Based on DP

This paper aims to develop a three-dimensional optimization model for railway alignment design based on Dynamic Programming. In the model, the optimization of railway alignment design is regarded as an optimization of 3-dimensional curves, and the formulation of optimization and the treatment of constraints are simplified by using DP. This model is more practically oriented than models based on optimization method of partial derivatives. In theory, the proposed model can give a global optimization solution. The proposed model is verified by data from P.R.China.

TYNE AND WEAR METRO: MANAGEMENT OF THE PROJECT.

The project involved well over 100 contracts for works designed and supervised by five firms of consulting engineers, the County Council and the Passenger Transport Executive, as well as new railway alignments by British Railways, and major service diversions by the statutory undertakers. The paper describes the necessary management of the project, giving details of the required organization, procedures for contract administration, techniques used in programming and cost control, special provisions for the scheme undertaken by the Executive on insurance and other items, and details of the capital cost of Metro.