Drop locks Lock (water navigation)

dalmuir drop lock

a drop lock allows short length of canal lowered temporarily while boat passes under obstruction such low bridge. during canal restoration, drop lock may used impractical or prohibitively expensive remove or raise structure built after canal closed (and re-routing canal not possible).

a drop lock can consist of 2 conventional lock chambers leading sump pound, or single long chamber incorporating sump - although term applies second case. pounds @ either end of structure @ same height, lock can emptied either allowing water run waste sump lower stream or drain, or (less wastefully) pumping water canal. particularly in two-chamber type, there need bypass culvert, allow water move along interrupted pound , supply locks further down canal. in case of single-chamber type, can achieved keeping lock full , leaving gates open while not in use.

while concept has been suggested in number of cases, example in world of drop lock has been constructed @ dalmuir on forth , clyde canal in scotland. lock, of single chamber type, incorporated during restoration of canal, allow replacement of swing bridge (on busy road) fixed bridge, , answer criticisms restoration of canal cause frequent interruptions of heavy road traffic. can emptied pumping – uses lot of electricity method used when water supplies adequate drain lock nearby burn. series of pictures showing operation of lock can seen here.