FOI request detail

Escalator Refurbishment

Request ID: FOI-0194-1718
Date published: 12 July 2017

You asked

I have completed statistical research and found significant results which has enabled me to progress on to producing engineering mitigation strategies. At this point I have ideas in mind and also lots of inspiration from around the worlds underground systems. It is clear from the TFL website that many escalator systems have been refurbished. These refurbishments are of great interest to me. If it was at all possible it would be of great help to myself if there are any available documents on the refurbishment work. If these documents could give information such as; why it was felt that they needed to be refurbished, the possible engineering designs considered, why this design was chosen, limitations on the redesigning of the system (possibly because of regulations or structural issues). I appreciate that this is not a usual request but if any available information or documents could be useful, they would be of great help towards me.

We answered

Thank you for your email received by us on 25 April 2017 asking for information about the refurbishment and design of London Underground escalators.

Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm that we hold the information you require.

Escalator Refurbishment – London Underground Definition and Summary

London Underground (LU) defines escalator refurbishment as follows:

“Replacement of a portion of the mechanical and electrical components of an existing escalator but retaining the significant structural elements (e.g. truss)”.

Within this definition, there are a number of categories of work:
• Full refurbishment (modernisation).
• Partial refurbishment.
• Extension of Life.

For the full and partial refurbishments the expected nominal life post-refurbishment of the escalator is 15~20 years - with the timing of the refurbishment intervention being dependent on the condition and usage of the escalator. The decision between full and partial is made based upon the machine in question and whole life cost considerations. The extension of life works are specific scope items to extend the life of an asset for a specified period (for example, two years extended life so that a full project can take place in line with a wider project at a station) until such time that the machine is totally replaced with a new machine.

Why it felt the escalators need to be refurbished

The escalators are refurbished to ensure safety, performance and reliability - this is invariably linked to machine operability and the management of risk should the machine fail. The risk could be safety risk or operation risk. A typical escalator consists of many mechanical and electrical components - many of these components are consumables or will degrade through time/usage due to wear and tear, therefore the need exists to refurbish and replace certain components before they fail. Escalators have a nominal design life of 40 years. Throughout this life they have a comprehensive intervention plan (including standard maintenance, handrail replacements and so on). A key intervention is the refurbishment usually undertaken at approximately half life to reset the residual life of mechanical and electrical components.

There are more than 427 escalators on the LU network and nearly 30 types of escalator. These escalators are all of varying age and condition and as such London Underground has a continuous work bank of escalator refurbishments. These refurbishments are prioritised based upon a number of factors, including:

• Performance of machine.
• Age of machine.
• Coordination with other works.
• Obsolescence.

These factors lead to a decision on the type of intervention required and an intrusive condition survey is combined with a pre-set assumed scope to decide the full scope of the refurbishment.

Possible Engineering Designs Considered – why this design was chosen
Historically, the above has been the core option. Escalators had a half life refurbishment and were then fully replaced, including all structural elements at the end of their life. The scope of these refurbishments have adjusted over time based on whole life cost considerations and obsolescence. For example, on some machines gearboxes are replaced and some are refurbished depending on how troublesome it is and the availability of spares etc. This scope variation is true of many other components of the escalator.

However, feasibility is currently taking place to consider the option of an “in truss replacement”. This means for old and poor performing machines there is the option to modify the truss and install a modern, modular escalator rather than refurbing the existing machine. This decision will be made going forwards on a business case basis.

In summary, there are three types of escalator refurbishments with regards to engineering options:

• Refurbishment where some or the majority of the mechanical and electrical components are replaced with ‘like for like’ components.
• Refurbishment where some or the majority of the mechanical and electrical components are replaced with modern equivalent components.
• Refurbishment where all the mechanical and electrical components are replaced with modern, modulised components with only the original escalator truss (structure) remaining.

The decision on which of the above is chosen is based on the type of machine, its condition and the cost of refurbishment.


Limitations on escalator refurbishments include:

• Escalator standards - LU escalators need to conform to EN 115 requirements.
• Space and access constraints.
• Closure constraints - an LU escalator undergoing a refurbishment intervention requires typically 16~18 weeks to complete the refurbishment works. During this time the escalator has to be closed off and would not be available for customer use.

Structural constraints do not generally apply to LU escalator refurbishments as the escalator structural truss is generally not affected during escalator refurbishments.


Overall, the strategy for escalator refurbishments is decided based upon ensuring safety and reliability for our customers at the lowest whole life cost.

I hope the above is useful, if this is not the information you are looking for, or if you are unable to access it for any reason, please do not hesitate to contact me.

Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.

Yours sincerely

Jasmine Howard
FOI Case Officer
Information Governance
Transport For London



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