We’re driving south on highway 2 heading to calgary. We had witnessed a RB Hanson transport truck almost hit the ditch and then regained control. Came up beside him and he had his head down texing( I assume) for a few min. Looking up occasionally and hadn’t even noticed me. After getting ahead of him I continued to watch in my rear view mirror and again he was all over the road and varing in his speeds. I believe this is very unprofessional and that many people’s luves are at risk while he is in the road.