WORLD BIGEST SHORT CUT 04

Safety features

A failure of the lock gates — for example, caused by a runaway ship hitting a gate — could unleash a flood on the lands downstream of the locks, as the lake above the locks (Gatun Lake or Miraflores Lake) drains through the lock system. Extra safety against this is provided by doubling the gates at both ends of the upper chamber in each flight of locks; hence, there are four gates in each flight of locks which would have to fail to allow the higher level of water to pass downstream. The additional gates are 21 m (70 ft) away from the operating gates.
Originally, the locks also featured chain barriers, which were stretched across the lock chambers to prevent a ship from running out of control and ramming a gate, and which were lowered into the lock floor to allow the ship to pass. These fender chains featured elaborate braking mechanisms to allow a ship up to 10,000 tons to be safely stopped; however, given the precise control of ships made possible by the mules, it was very unlikely that these chains would ever be required. With many modern canal users being over 60,000 tons, and given the expense of maintaining them, the fender chains were reduced in number in 1976 and finally removed in 1980.
Beyond this, the original design of the locks had yet another safety feature — emergency dams which could be swung across the locks at the upper end of every flight. These consisted of swinging bridges, from which girders were lowered to the lock floor; steel shutters could then be run down these girders to block the flow of water. Monthly drills were held, by night and day, to make sure that these dams could be deployed in an emergency.
In the late 1930s, the original dams were replaced by new dams, which were raised out of slots in the bottom of the lock chambers, either hydraulically or by compressed air. The new dams were themselves retired in the late 1980s, and today, no emergency dams are in place.