On 08/08/2014 19:40, Nightjar "cpb"@ insert my surname here wrote:

I have always thought it a pity that it was ruled that the human voice
was a suitable audible warning device. A shout could mean anything and I
think people are quite likely to ignore it, on the basis that they would
rather not get involved with somebody shouting in the street. A bicycle
bell was a very distinctive sound and gave pedestrians much better
warning of a fast approaching hazard.

I find calling out to people works very well. I normally use a greeting,
timed to allow for the inevitable dithering which happens as people work
out what's going on. There seems to be no difference in the dithering
when friends use a bell in a similar situation.