There were severe delays on Monday on one of the key Tube lines that will take people to the Olympics.
The problem, due to a fault with the platform-edge doors, was at North Greenwich - close to the Olympic site at Stratford.
It meant long hold ups on the Jubilee line in the early part of the morning rush hour.
There were also minor delays today on another main transport route to Stratford, the Docklands Light Railway, due to a signalling problem at Canning Town.
Monday's delays follow a series of problems on the Tube last week including part-closure of some lines.