The cars facing us in the left lane on southbound Primrose are turning left onto Colonial. Those drivers want to make the light, so they’re looking for the first opportunity to dash across — creating the potential for a left cross.
Traffic flow is dynamic. It often has different characteristics at different times of day. It is also influenced by road design as well as upstream and downstream interchanges. Once you understand these influences, you can predict and exploit these patterns for easy travel through complex situations.