I frequently see the above given as the reason for delays. I can see for example that this is currently causing delays between Wigan North Western and Preston. Out of interest, and apologies if it's a silly question, but just what kind of objects generally do get caught on the overhead wires and cause delays? For example, could it be something as light/small as a plastic bag blown onto the wires by the wind? Or is it generally something more substantial than that?