Staircase locks Lock (water navigation)

staircase of 5 locks, dating 1774, @ bingley, england

where steep gradient has climbed, lock staircase used. there 2 types of staircase, real , apparent .

a real staircase can thought of compressed flight, intermediate pounds have disappeared, , upper gate of 1 lock lower gate of 1 above it. however, incorrect use terms staircase , flight interchangeably: because of absence of intermediate pounds, operating staircase different operating flight. can more useful think of staircase single lock intermediate levels (the top gate normal top gate, , intermediate gates tall bottom gate). there no intermediate pound, chamber can filled emptying 1 above, or emptied filling 1 below: whole staircase has full of water (except bottom chamber) before boat starts ascend, or empty (except top chamber) before boat starts descend. building pair of such lock sets (one used climb , other descend) these difficulties avoided, enabling greater traffic volume , reduced wait times.

in apparent staircase chambers still have common gates, water not pass directly 1 chamber next, going instead via side ponds. means not necessary ensure flight full or empty before starting.

examples of famous real staircases in england bingley , grindley brook. two-rise staircases more common: snakeholme lock , struncheon hill lock on driffield navigation converted staircase locks after low water levels hindered navigation on bottom cill @ higher tides – new bottom chamber rises far enough boat on original lock cill. in china, completed 3 gorges dam includes double five-step staircase large ships, , ship lift vessels of less 3000 metric tons. examples of apparent staircases foxton locks , watford locks on leicester branch of grand union.

instructions descent of treble staircase, chesterfield canal

operation of staircase more involved flight. inexperienced boaters may find operating staircase locks difficult. key worries (apart being paralysed indecision) either sending down more water lower chambers can cope (flooding towpath, or sending wave along canal) or emptying intermediate chamber (although shows staircase lock can used emergency dry dock). avoid these mishaps, usual have whole staircase empty before starting descend, or full before starting ascend, apart initial chamber.

one striking difference in using staircase of either type (compared single lock, or flight) best sequence letting boats through. in single lock (or flight room boats pass) boats should ideally alternate in direction. in staircase, however, quicker boat follow previous 1 going in same direction. partly reason staircase locks such grindley brook, foxton, watford , bratch supervised lockkeepers, @ least during main cruising season, try alternate many boats up, followed down there chambers in flight.

as flight, possible on broad canal more 1 boat in staircase @ same time, managing without waste of water requires expertise. on english canals, staircase of more 2 chambers staffed: lockkeepers @ bingley (looking after both 5-rise , 3-rise ) ensure there no untoward events , boats moved through speedily , efficiently possible. such expertise permits miracles of boat balletics: boats travelling in opposite directions can pass each other halfway staircase moving sideways around each other; or @ peak times, 1 can have chambers full simultaneously boats travelling in same direction.