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Driveability

‘Driveability’ describes how easy it is for train drivers to take trains along a particular route safely and reliably. Driveability is influenced by the interaction of the signalling system with the trains being operated.

Driveability can be impacted by planned changes to the infrastructure – such as the track layout, signalling, structures or surrounding environment, or to the types of train operated.

Getting driveability ‘right’ means that implementing the changes will help the railway to realise the intended safety and performance benefits. These may have been used to justify the original investment, for example to achieve more frequent train services.

Getting driveability ‘wrong’ might have safety risk and performance implications. These could have a negative knock-on effect on passengers and freight customers, who rely on a smooth-running railway. They expect to benefit from safe, reliable and frequent services.

You should have a good understanding of the impact on driveability of the change you are making. You should be able to take good project decisions that result in a railway that is fit for purpose.

New RSSB standards capture years’ of industry-agreed best practice. This can be used by signalling projects to confirm that planned changes to lineside signalling systems are fit for purpose and ensure routes are sufficiently driveable.

If you are proposing a change, conforming to these standards can help you fulfil your legal obligations in applying the Common Safety Method for Risk Evaluation and Assessment (CSM RA).

Good practice

Driveability needs to be considered early

From the start, put engineering projects into an operational context, think about what impact you could be having on train operators and signallers.

If driveability is considered early on in a project lifecycle, this can avoid potential objections when proposed changes are formally consulted with stakeholders, and avoid late design changes with the associated timescale and cost implications.

Consider the impact of driveability on:

  • train operations, including the train driving task
  • signalling and infrastructure operations
  • station operations, including train dispatch
  • train planning, including service recovery operations
  • timetabling
  • asset management, including possessions.

Get the right people involved

RSSB workshop

Make sure the project teams are talking to people who are capable and familiar with the ways in which the work could affect their business operations.

Make senior leaders aware of the importance of freeing up people’s time to participate in discussions and assessments.

Encourage people with operational roles to support design decisions

The best people to judge whether a route is driveable are the people who will actually be operating the railway. Decisions about driveability benefit from collaborative input from users of the system, including drivers, signallers, train planners and asset managers. This can be direct input to inform the design or support to driveability assessment.

Use simulators

Technology, including simulators and VR, can be used to help make dialogue more efficient and to assess driveability of designs before practical implementation begins.

Exercise the right amount of effort

RSSB workshop

Effort should be in proportion to the risk concerned and the benefits. Driveability assessment does not necessarily need to be a lengthy academic exercise. Decision makers do need to be satisfied that risk has been managed in a way that satisfies their organisation and the law. Changes that don’t result in much change to the overall driveability may only need documentation of short dialogue between the parties concerned. That said, subtle changes to the infrastructure can still result in a big impact to driveability. In all cases, focus on getting the right people engaged and especially the people who will ultimately be affected by the changes.

Standards

In March 2018, we published three new rail industry standards that capture industry-agreed best practice in lineside signalling system design and signalling layout driveability assessment.

We also published a guidance note that sets out the industry-agreed best practices in applying standards and risk assessments to confirm that planned changes to lineside signalling systems are fit for purpose.

  • RIS-0713-CCS - Driveability Assessments describes what needs to be done to assess driveability and provides guidance on how to manage the assessment.
  • RIS-0758-CCS - Lineside Signal Aspect and Indication Requirements replaces GKRT 0058 and sets out the requirements for the appearance and meaning of lineside signal aspect and indications. There are very few material changes to the requirements.
  • RIS-0703-CCS - Rail Industry Standard on Signalling Layout Requirements contains updated requirements for lineside signal aspect sequences, junction signalling and provision of lineside signalling equipment. This replaces GKRT 0045 and GERT 8071, which are withdrawn. Although the requirements look different, there are very few material changes to the way lineside signalling systems are designed.
  • GEGN8651 - Guidance on safe integration of change affecting CCS system interfaces is a new guidance note that explains how the various types of compatibility assessment and risk assessment are used to support decisions about safe integration of lineside signalling systems.

All these documents are available to download from our Standards Catalogue.

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