Overhead Line Force Measurement System for Network Rail

Article: Overhead Line Force Measurement System for Network Rail


In November 2018, DB ESG received a contract from Network Rail to provide DB Systemtechnik’s (DB ST) proven overhead line monitoring equipment to enhance Network Rail’s existing infrastructure monitoring fleet.

DB ST’s Overhead Line (OHL) Force Measurement System has been used by Deutsche Bahn and other operators across the world for over 20 years. It is similar equipment to that also used by DB ST and DB ESG for the commissioning of new train fleets on UK infrastructure and has also been used to commission new OHL electrification constructed on the UK’s Midland Mainline.

One monitoring system was deployed onto Network Rail’s Mobile Electrical Network Testing, Observation and Recording (Mentor) Test Coach. The overhead line monitoring system fitted to Mentor is now working as promised and is being regularly used by Network Rail to monitor and measure overhead line quality and report any issues.

DB ESG has also installed a single system onto a Class 390 Pendolino unit to cover the West Coast Main Line infrastructure.  This unattended and standalone system is providing data daily, via normal passenger train service operation.  The regular collection, including automated real-time reporting of defined quality exceedances, and assessment of asset condition data will support Network Rail’s ambition to move towards a ‘predict & prevent’ maintenance approach.

In October 2020, DB ESG was awarded a further contract from Network Rail to provide technical support for the Mentor and Class 390 Pendolino overhead line monitoring systems. This additional order is for the provision of support for ten years. This contract marks a significant shift in DB ESG’s offerings to the market, supplying services beyond its normal standard warranty period provision.

In February 2023, Network Rail’s Infrastructure Monitoring Project was awarded ‘Innovation of the Year’ at the Rail Business Awards. The monitoring of the West Coast Main Line infrastructure using a Class 390 Pendolino formed part of this award winning submission.

Overview of Monitoring System

This system provides the following data to Network Rail:

  • Contact force
  • Wire height
  • Location data
  • Wire stagger
  • Accelerations

This Force Measurement System (FM) measures the dynamic interaction between a measurement pantograph and the overhead line system.  Light weight sensors for vertical forces and accelerations are installed on an appropriate position on the pantograph head.  In addition, sensors for measuring longitudinal acceleration are installed on the pantograph. 

A data acquisition unit mounted to the pantograph base frame converts the measuring signals received from the pantograph sensors, so that they can be transmitted via optical fibre into the interior of the measurement vehicle for evaluation via a measurement computer. 

The data acquisition box contains additional sensors for vertical + lateral accelerations and also measures accelerations resulting from the track.  During off-board analysis by Network Rail, it is possible to determine whether measured high accelerations at the pantograph result from high accelerations caused by the track.  

The distribution of the forces (left/right) over the contact strip is a direct measure for the stagger.  It is corrected by measuring the tilt of the car body.  To measure the movement of the bogie, potentiometers measure the distance between the axle boxes and the car body, together with the lateral movement of the bogie.   Potentiometers also measure the angle between the pantograph base frame and the pantograph lower arm - an indirect measure of the dynamic height of the contact wire

A temperature sensor is integrated into the data acquisition box and a wind sensor is mounted on the car roof. 

In addition to the sensor data received from the data acquisition box, Line Voltage at the contact wire is measured via an additional roof mounted insulator with an integrated voltage transformer. 

The measurement systems are provided with USB, WIFI and ethernet interfaces to facilitate the bulk download of measurement data.

DB ST post processes the saved data to add location information.

Work Undertaken by DB ESG for both MENTOR and Class 390

  • Detailed vehicle surveys.
  • Concept designs created.
  • 3D CAD models developed to validate the equipment installation locations.
  • Detailed designs produced.
  • Structural and electrical assessments carried out.
  • Evidence of compliance against mandatory requirements for each area was completed by DB ESG and assessed by Railways Approvals Ltd. (independent certification body).
  • Drawings produced for all installations, assemblies, manufactured items and modifications, including fixing brackets, general arrangements, wiring looms, electrical schematics and wiring diagrams.
  • Modification procedures written to accompany the installation drawings
  • Bill of Materials produced.
  • DB ESG was responsible for providing all materials and equipment required to deliver modifications, in a kitted form, with two years’ warranty on all supplied materials and equipment.
  • Equipment installation onto the vehicles.
  • A testing and commissioning strategy created and delivered.
  • Tethered and dynamic testing undertaken to commission the systems on the vehicles.
  • Training for maintenance personnel was carried out during system installation and static testing
  • Training for Network Rail Operational employees was carried out during the commissioning test runs: -
    • System introduction.
    • System operation.
    • Calibration of the system.
    • Maintenance.
    • Error diagnostics.
    • Review and analysis of data collected.

Work Undertaken by DB ST for both MENTOR and Class 390

  • The equipment was supplied, tested, calibrated, and validated on DB ST’s pantograph test bench in Munich, including wind tunnel tests to determine aerodynamic influence.
  • Production of system calibration and validation reports.
  • Calibration certificates of the measurement systems issued prior to shipment.