Railway Electrification Survey

A multi-disciplinary project requiring close coordination among electrical, signalling/telecommunications, and civil engineering disciplines for railway electrification.

Selecting between conventional 25 kV and 2 x 25 kV Auto Transformer systems for power supply, based on boosting transformers, return conductors, power demand and substation location.

A system of railway traction using 25 kilovolt alternating current electricity.

Maintenance facilities, modification of power supply, liaison with electric authorities, and consequential electrical work for service buildings and staff quarters during electrification projects.

Installation of colour light signals and protection of signalling & telecommunication circuits from induced traction voltages.

Yard remodeling, track changes, loco shed construction, modifying bridges/tunnels/platforms for 25 kV AC clearances.

Unwanted voltages created by the traction power system that can affect other systems, necessitating mitigation.

The distance from the center of a turnout to the toe of the turnout.

The distance from the center of a turnout to the nose of the turnout.

The furthest distance an Overhead Line Equipment structure can be from a turnout's center.

The required separation between contact wires at a turnout support.

The smallest allowable horizontal distance between two contact wires.

OHE structures should not be placed closer than 10m behind a signal or closer than 30m ahead of a signal.

Required stagger for the turnout's contact wire for clear movement.

The range of permissible distances between tracks for the placement of OHE structures at turnouts (150 to 700mm).

OHE structures should be no closer than 10 meters behind a signal.

OHE structures should be 30 meters or further from the signal.

The traffic level (in Gross Million tonne per route kilometer per annum) at which the minimum acceptable rate of return is achieved for an investment.

A method to assess the profitability of an investment, considering social costs and benefits, using discounted cash flow (DCF) techniques, and specific discount factors.

The use of electricity to power railway locomotives.

The use of diesel engines to power railway locomotives.

The allocation of resources to create electric railway infrastructure and equipment.

A benefit of electric traction compared to diesel systems.

A benefit of electric traction due to potentially higher efficiency and capacity.

Benefits of electric traction in terms of maintenance, fuel, etc.

A benefit of electric traction compared to diesel, concerning the upkeep of the locomotives.

The minimum distances between semaphore signals for safety and visibility, with longer distances required for structures beyond the first.

Distances for colour light signals are regulated, shorter for signals with route indicators and longer for stop signals.

Signal locations on curved tracks are determined jointly by electrical and signal engineers to ensure good visibility, considering curvature and terrain.

Insulated overlaps are located at strategic points for sectioning, paralleling posts, and boosting transformer stations, ensuring smooth power flow.

Uninsulated overlaps are placed to maximize tension lengths and minimize the number of overlaps in a section.

The distance between the anticreep central mast and balance weight anchor mast at an overlap is limited to 750m for regulated OHE.

The maximum tension length for regulated OHE is 1500m, while unregulated OHE allows 2000m due to the lack of anticreeps.

On sharp curves (radius ≤ 5000m), a 4-span overlap is needed, requiring a central structure with two brackets.

The distance from the anticreep to the center of the 4-span insulated overlap is limited to 600m to ensure safe clearance.

The 4-span insulated overlap has two brackets on different elementary sections to maintain the required clearance between them.

Designing overhead line equipment (OHE) within tunnels requires careful consideration of factors like span length and headroom, especially for large encumbrances. Short spans are crucial to ensure sufficient clearance, and anticreeps and overlaps should be avoided unless the tunnel is long. To minimize speed restrictions due to OHE, unregulated OHE can be considered for long tunnels with limited temperature variations.

The OHE support location on girder bridges should be carefully considered. The design may be finalized after the bridge is complete, but the feasibility of supporting the OHE on specific truss members needs to be established beforehand during the survey.

When yard remodelling or doubling works are planned , OHE design should be flexible to accommodate such changes. Both the track and OHE designs should aim for economic solutions that minimize traffic disruption during remodelling.

Civil engineers responsible for tracks and OHE design engineers should collaborate to determine the most cost-effective and efficient plan for remodelling, involving the placement of turnout toes and track alignments.

Permanent benchmarks indicating the locations of turnout toes and new track alignments should be established during the survey. These benchmarks are critical for the accurate placement of OHE structures.

A detailed, meticulous survey of the railway route for electrification, measuring every portion meticulously, which forms the foundation for the Overhead Equipment (OHE) layout.

Scale drawings that capture the detailed information obtained from the foot by foot survey, used to design the OHE layout.

Initial plans for the OHE layout based on the survey sheets, which are then verified and adjusted at the site.

The final, approved OHE layout plan, incorporating site adjustments, which forms the basis for quantity estimations and construction tenders.

A logbook maintained by surveyors to record all the details observed during the foot by foot survey, which aids in preparing the initial survey sketches.

Initial drawings created based on the field book recordings, depicting the surveyed area, which are then used to create the complete survey plans.

An accurate foot by foot survey ensures precise placement of OHE structures, optimizes material quantities, minimizes construction errors, and guarantees a safe and efficient electrification project.

A plan to improve the track structure before OHE installation, ensuring the altered track geometry doesn't hinder OHE construction.

Collaborating with open line officials during surveys to ensure the OHE design aligns with existing and planned track improvements.

Detailed drawings made on site during surveys, capturing all relevant information to avoid needing to return.

Drawings that show both the existing track layout and the planned track layout after improvement.

The abbreviation OHE stands for Over Head Equipments which includes the catenary system providing power to trains.

The vertical distance between the chord and the arc of a curve, measured in millimetres for survey purposes.

The Research Designs and Standards Organisation, which sets guidelines for railway infrastructure, including OHE.

A detailed plan of the OHE system, including the run of conductors, structure types and locations, and any special features like clearances for overline structures.

The Pegging Plan is derived from a detailed survey of the existing track and includes information like track centers, span lengths, versines, and the locations of structures and anchors.

The Pegging Plan serves as the basis for estimating the quantities of work and materials needed for the OHE construction project, and for finalizing tender schedules.

The process of checking the prepegging plan on-site, making necessary adjustments for real-world conditions. This may involve changing structure locations, overlaps, or anchors for optimal efficiency.

A structure that secures the OHE contact wire and other conductors to the ground, ensuring stability.

A mechanical device fitted to the OHE contact wire to prevent it from sliding along the catenary in case of tension changes.

A structural arm extending from a mast that supports the OHE contact wire, allowing the wire to pass over curves or switches.

A section of the OHE where two or more contact wires are connected to ensure smooth power flow.

A section of overlap where the contact wires are insulated, allowing for independent control of power supply to different sections of the track.

A section of overlap where the contact wires are not insulated, used to maximize tension lengths and reduce the number of overlaps.

A location where the power supply to the OHE can be manually controlled, often used in conjunction with insulated overlaps.

A transformer that steps up the voltage of electricity to provide adequate power supply to the OHE, especially over longer distances.