Panama Canal Locks - Design

Design

There are three sets of locks in the canal. A two-step flight at Miraflores, and a single flight at Pedro Miguel, lift ships from the Pacific up to Gatun Lake; then a triple flight at Gatun lowers them to the Atlantic side. All three sets of locks are paired; that is, there are two parallel flights of locks at each of the three lock sites. This, in principle, allows ships to pass in opposite directions simultaneously; however, large ships cannot cross safely at speed in the Gaillard Cut, so in practice ships pass in one direction for a time, then in the other, using both "lanes" of the locks in one direction at a time.

The lock chambers are 110 ft (33.53 m) wide by 1,050 ft (320 m) long, with a usable length of 1,000 ft (305 m). These dimensions determine the maximum size of ships which can use the canal; this size is known as Panamax. The total lift (the amount by which a ship is raised or lowered) in the three steps of the Gatun locks is 85 ft (25.9 m); the lift of the two-step Miraflores locks is 54 ft (16 m). The single-step Pedro Miguel lock has a lift of 31 ft (9.4 m). The lift at Miraflores actually varies due to the extreme tides on the Pacific side, between 43 ft (13 m) at extreme high tide and 64.5 ft (20 m) at extreme low tide; the tides on the Atlantic side, however, are very small.

The lock chambers are massive concrete structures. The side walls are from 45 to 55 ft (14 to 17 m) thick at the bases; towards the top, where less strength is required, they taper down in steps to 8 ft (2.4 m). The centre wall between the chambers is 60 ft (18 m) thick, and houses three long galleries which run the full length of the centre wall. The lowest of these is a drainage tunnel; above this is a gallery for electrical cabling; and towards the top is a passageway which allows operators to gain access to the lock machinery.