Bobbing is where the signal changes from red to green and back again or vice
versa. Its caused by something causing the track circuit to be made, like
water lying on the track, imitating a train. So signalers dont know whats in
the area, the train stops raise up and everything stops. Then once its been
found the area is empty and its a fault, drivers can go past the signal but
at reduced speeds etc....a little more detail but i wont bore you. This
causes a backlog and the cycle of delay starts.......


wrote in message
oups.com...

DistrictDriver wrote:
Chris wrote:
The section between
East Putney and Wimbledon is signalled and controlled by Network
Rail,
and there is a long standing problem down there with signals
'bobbing'
with the slightest shower of rain! Hopefully this will be addressed
before too long.

Can you explain what bobbing is.

Kevin