As part of CRT's desire to reach out to the public, they have been holding Open Day events during their main maintenance period (2014/15). Where locks have been drained for work to be carried out, they have allowed public access over a weekend to show what is being done. This set of photos were taken at the event at Bedford Street Staircase on 1st Feb 2015.
Stop-planking is used to block the water in the upper pound before the locks are drained. There are grooves in the sidewall at strategic places all round the canal network so that, in the event of a breach in the canal wall, such planks can be dropped in to restrict the amount of water lost. They are also used when it is necessary to intentionally drain sections for repair work.
The work being carried out during this maintenance period was the replacement of the facings where gates close onto each other and the lock bottom. Wooden strips create the seal. Other work involved checking and re-pointing brickwork in the lock walls.
This photo shows one of the paddles which permit water to enter the lock chamber thus filling the lock. A rod passes from the top of the paddle to (usually) a rack and pinion system turned by boaters using a windlass. The paddles on these narrow locks are considerably smaller than those in wide locks (compare photo taken at Hatton Locks ).
Taken from the floor of the middle lock, the bottom gates can be seen ajar in the background. About 2/3 of the way down the left of the picture are the paddles to drain the middle lock into the bottom one. The "ramp" of concrete in the centre of the lock bottom is there as a height marker for the cill between the locks - a boat of too much draft would hit the "ramp" instead of causing damage to the wood-faced cill.