Have you ever been standing at a subway station in Toronto, impatiently waiting for your train to arrive with absolutely nothing to do, when you look down and notice that the tracks are covered with seemingly pointless little rocks? 

If you have, you're likely not alone, but it turns out those rocks actually have a name and a purpose after all. 

According to a thread posted by the TTC Customer Service Twitter account Tuesday afternoon, the stones are called "track ballast," and they serve several different important purposes.

One of these functions is to bear the load of the tracks, according to the TTC. 

Did you know there’s a name for the small rocks that are found around subway tracks? They are called “track ballast” and they serve an important purpose – one of which is to bear the load of the tracks.

— TTC Customer Service (@TTChelps) August 10, 2020

Network Rail, the company that owns and operates Britain's railway infrastructure, says ballast also "helps with drainage, so rain water can drain away rather than pooling, and with preventing vegetation growth, which could destabilise the track and be a hazard for anyone working on the railway."

Ballast is packed between, below, and around the railway ties (the rectangular support for the rails in the tracks) to prevent them from moving and keep them in a firm position when trains go by.

During last week's nightly early closures, the TTC says workers delivered ballast to the Broadview turnout, which is the last step for this project, and they also completed power rail welding as part of the beam replacement work.

During last week’s nightly early closures Track Maintenance delivered ballast to the Broadview turnout, the last step for this project and completed power rail welding as part of the beam replacement work. Structure Maintenance achieved grout pad repairs and invert chipping. pic.twitter.com/uX1fuvYPQC

— TTC Customer Service (@TTChelps) August 10, 2020

In the maintenance update, the TTC also said teams performed Automatic Train Control testing during the weekend, including speed testing for the next phase of the project between Queen Station and Rosedale Station. 

"These tests bring us one step closer to extending ATC service on Line 1 from Vaughan Metropolitan Centre Station to Rosedale Station which will help make our service faster and more reliable," they tweeted. 

"Thank you, customers, for your patience as we work to improve our service."