yup, just love walking the bike down the freeway in a traffic jam.... You won't be able to avoid every blind spot. But you will be able to control the distance to the vehicle in front of you. No choice there. Set your distance ahead, and deal with the rest of it. Move with a car that moves into your lane. Take the next lane over, drop back, ride between lanes, or take the berm/median. Whatever gets out of the way, until you can get back to normal travel. The horn is useless unless it's Moose's air horn. Sometimes, but seldom, even suddenly accelerating is good, if it's clear ahead and not so clear behind. Watch for people on cell phones, or otherwise not paying attention. Those are the ones most likely to do something stupid, like a sudden lane change, and not to signal when doing so. Their blind spot is bigger. Well, infinite... I've seen packs of cars where all are doing this, weaving and wobbling and not signaling at all. Can't figure out why they aren't hitting each other. Rare, but I'm going to drop back and let them wreck on their own. I've found that generally, if I slow down a bit, and give myself more room ahead, the car behind me will give me more room behind me. Most people really aren't stupid, and really don't want to wreck.