How to describe a triggering condition when a vehicle reaches a certain lane (not a position)?

Is there any way to describe the condition when a vehicle reach a certain lane (not a position)? For example, we want to capture the condition when ego changes to adjecent lane regardless of where on the road it changes, as long as it changes to the other lane, then trigger some action. It looks like you have to define a certain position in ReachPositionAction, which means you have to define both s and t. But here we only care about t NOT s.