Intersections are recipes for disaster: turning right or left successfully depends on close consideration, good decision-making, and trust in the drivers around you.
Drivers must know (and follow) the rules of the road and be aware of vehicles trying to squeeze in at the side of the truck, but there are also ways for fleet operators to help their drivers avoid collisions when turning. A training refresher is never a bad idea: it gives you the chance to focus more generally on defensive driving best practices, but address problematic behaviour more specifically, as well.