Escalator and elevator refurbishment projects are extremely lengthy because most of the replacement parts needed to overhaul old escalators/elevators are no longer stock items and need to be custom made. In the worst case, parts may need to be reverse-engineered, re-designed to be compatible with current materials and manufacturing processes, prototyped, tested, and made through limited-run production.

If an escalator/elevator is shut down for a few months (or years) due to refurbishment, it's because worn, but vital, parts of it have been removed for use as reference materials so replacements can be made. It is also possible that vital parts could be too worn for the escalator/elevator to operate safely until new parts have been made and installed.

I'll also point out that published information on the Runnymede project indicates that the current round of construction started at the end of 2018, involved the addition of three underground elevator shafts, and is expected to be completed at the end of 2020[0]. Unless you are referring to earlier work, your '5-7 year' timeline to 'clean an escalator' is a vast exaggeration.

[0] http://ttc.ca/Service_Advisories/Construction/Runnymede_EA.j...