I recently visited the VIA/GO Station in Oshawa to see how the construction is progressing. The third track has now been installed, but still needs to be aligned and tamped. Crews are also working on the new platform.
While I was watching, I was lucky enough to catch RG 309, a Loram rail grinder, as it sped through the station.
What's a rail grinder?
Metal rails take quite a beating thanks to heavy metal wheels rolling over them all the time. When the rail gets worn, it causes damage to wheels and make for a rougher ride. To fix this, railways use rail grinders to smooth the tops of the rails, restoring the smooth ride and thus preventing further wear and tear.
I have yet to see a rail grinder actually at work. It's quite a sight to see, as this video shows.