For the situation that you describe - when others are doing 5-15mph, it's still alright for filtering. Keep a close eye on the heads of drivers where you can see them, as people often turn their heads slightly if they're going to change lane. Also watch for the wheels angling or the car moving slightly to one side in readiness for a lane change. It's very rare that a driver will change lane without giving anything away in the seconds before they move. A lot of the time you can spot them planning to move before they even start moving.
If you can't see the drivers head, or aren't sure if they've seen you (or aren't sure for any other reason, even if it's just a gut feeling) then wait or go past slowly so that you have more time to react if they do something daft.
|