T2 lanefine

I was travelling on M3 to CBD this morning, the traffic wasn’t bad but there were still a lot of vehicles on every lane, except for this right lane where it says transit T2 on the sign and there are barely any vehicles travelling on this lane, it was around 9:30 that time and I decided to drive on that lane all the way to the end of the freeway (I only see 1 or 2 vehicles behind me during the travel). I’m just curious if there are restrictions for driving on the T2 lane because it seems many drivers are avoiding this lane.