CRANE EQUIPMENT AND CONSTRUCTION OF THE PANAMA CANAL 

A PICTORIAL HISTORY OF THE CONSTRUCTION OF THE PANAMA CANAL

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The Panama Canal Locks, which lift ships up 25.9 m (85 ft) to the main elevation of the Panama Canal, were one of the greatest engineering works ever to be undertaken at the time, eclipsed only by other parts of the canal project. No other concrete construction of comparable size was undertaken until the Hoover Dam in the 1930s. The total length of the lock structures, including the approach walls, is over 3 kilometres (nearly two miles).

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 Lake Gatun; 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 33.53 meters (110 ft) wide by 320.0 meters (1050 ft) long, with a usable length of 304.8 metres (1000 ft). 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 25.9 m (85 ft); the lift of the two-step Miraflores locks is 16.5 m (54 ft). The single-step Pedro Miguel lock has a lift of 9.5 m (31 ft). The lift at Miraflores actually varies due to the extreme tides on the Pacific side, between 13.1 m (43 ft) at extreme high tide and 19.7 m (64.5 ft) 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 13.7 to 15.2 metres (45 to 55 feet) thick at the bases; towards the top, where less strength is required, they taper down in steps to 2.4 m (8 ft). The centre wall between the chambers is 18.3 m (60 ft) 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.

For nearly ten years, the focus of the excavation effort was Gaillard Cut (formerly known as Culebra Cut), where the canal passes through nine miles of craggy hills. Slopes in the cut are very unstable, and work was hampered by constant slides that buried machinery, increased the volume of excavation, and extended construction by almost two years. These slides and the limitations they impose on the width of the channel are major constraints of the Canal. While the width of the original 300-foot channel has been doubled, the cut remains too narrow for large ships to pass one another.