In the 7 on Severn Bridge last week a lump of something hard fell from a truck, bounced in front of the car forcing me to duck behind the full screen. Luckily, the "thing" smashed into my offside headlamp with sufficient force to push back the bowl. Obviously I felt peed off about the incident but now appreciate it could have been a lot worse. What if I'd had an aeroscreen and the lump bounced high enough to hit me in the face? Would a helmet have been sufficiently protective?