One of our selected pictures shows workers taking out the last remaining old lock gate at Bingley Five Rise Locks in 2012.
The locks - the steepest flight  in the UK - were drained to allow the installation of new gates. These  are made of English green oak and, taken together with the balance beam, weigh more than 5 tonnes
The famous staircase lock underwent extensive restoration in 2004 and again in 2006, when the lock gates and paddles were replaced. As is expected with such a feat of engineering, the lock requires a great deal of maintenance. 
Five-Rise Locks has a gradient of about 1:5, a rise of 59 ft 2 in (18.03 m) over a distance of 320 ft (98 m).
Another view shows workers in days gone by, while in 2004 lock keeper Barry Whitelock is pictured checking the lock during repairs.