Turnkey supply of interoperability modifications to Mk4 coaches, Mk4 DVT and Class 67 locomotives for Transport for Wales Rail

Article: Turnkey supply of interoperability modifications to Mk4 coaches, Mk4 DVT and Class 67 locomotives for Transport for Wales Rail


Transport for Wales Rail (TfWR) had a requirement to have an additional five 5-car rakes of Mark 4 (Mk4) coaching stock operated with a Class 67 locomotive and a Mk4 DVT. This was to complement their three 4-car rakes already in-service that had been previously modified by DB ESG in a separate contract with Eversholt Rail during 2018/19. The control systems for these vehicles were not compatible and so modification work was necessary to enable them to operate in revenue earning service. This project not only involved compatibility modifications, but also reconfiguration of the CCTV, rotation of the POD vehicle in the rake and dynamic brake testing to allow them to be fully functional in passenger service.


DB ESG was responsible for the engineering, design, materials, installation, testing & commissioning, approvals and associated vehicle movements on the network for this project.

In 2017, DB ESG undertook a feasibility study to understand the work required to enable Class 67s to operate Mk4 coaches. This study helped to create the work scope for this project, which included: -

  1. Installation of a 42-way hardwired through control system onto all the coaches and DVT. The cable harnesses routed through the roof space, with a receptacle and mounting box installed on the body ends. During the project it was identified that the service vehicle brake frame required modification to the main reservoir pipes. Additional interfaces to the FDM control system were also required, including for the passenger emergency brake and override system, door control circuits, and public address and crew communications. The existing TDM based control system was removed.
  2. Additional controls were needed for the Class 67 locomotives, including new passenger communications alarm, signal buzzer equipment and a interface with the existing PA and crew communications equipment.
  3. Additional controls were also required for the DVT to enable compatibility, including modifications to the desk controls and the power controller.

Work Undertaken by DB ESG

  • Vehicle surveys were carried out to confirm the concept design.
  • Development of the concept design for the required Mk4 enhancements. 3D models were created of the applicable installation locations for the equipment necessary. A concept design document was produced for review and acceptance by the customer.
  • The concept design was turned into a detailed design, together with structural and electrical assessments. Design documentation with drawings were produced for first-in-class fitment.
  • Drawings were developed for all installations, assemblies, manufactured items and modifications required for all vehicle types, including fixing brackets, wiring looms, electrical schematics and wiring diagrams.
  • Modification procedures were produced to accompany the installation drawings.
  • A complete Bill of Materials was provided for procurement purposes.
  • Railway Approvals Ltd. independently approved and certified the modifications.
  • Provision of all the materials and equipment required to complete the modifications.
  • 12 months warranty was provided for all supplied materials and equipment, and all work undertaken.
  • The first-in-class installation was carried out to verify the design and was overseen and supported by DB ESG.
  • Production of a testing and commissioning strategy, designed to provide a staged approach to implementation of the new system interfaces, train control and operating systems for each vehicle type.
  • On site support provided to the operator to assist with the fleet introduction.