page_title: Panama Canal locks
section_title: Safety features
hierarchical_section_title: Panama Canal locks / Safety features
caption_attribution_description: Deutsch: Schutzketten bei der Miraflores Schleuse, von der Durchfahrt des Linienschiffs Schlesien am 8. März 1938. Vgl. auch Spraul, G.: Vom Fähnlein zur Fahne in den Tod, ISBN 978-3-86634-502-7, Seite 637ff. English: Fender chains of the Miraflores locks, from the passage of the SMS Schlesien on 8 March 1938. Also published in Gunter Leopold Spraul (2008) Vom Fähnlein zur Fahne in den Tod: Tagebücher und Aufzeichnungen des Leopold Schuhmacher (†1943) Oberleutnant zur See [From the Pennant to the Flag and unto Death: The Diary and Records of Leopold Schuhmacher (died 1943), Senior Lieutenant at Sea], Halle (Saale): Projekte-Verlag Cornelius, p.&#160;370 ISBN 978-3-86634-502-7
context_page_description: The Panama Canal locks are a lock system that lifts ships up 85 feet to the main elevation of the Panama Canal and down again. The original canal had a total of six steps for a ship's passage. The total length of the lock structures, including the approach walls, is over 1.9 miles. The locks were one of the greatest engineering works ever to be undertaken when they opened in 1914. No other concrete construction of comparable size was undertaken until the Hoover Dam, in the 1930s.
  There are two independent transit lanes, since each lock is built double. The size of the original locks limits the maximum size of ships that can transit the canal; this size is known as Panamax. Construction on the Panama Canal expansion project, which included a third set of locks, began in September 2007, finished by May 2016 and began commercial operation on 26 June 2016. The new locks allow transit of larger, New Panamax ships, which have a greater cargo capacity than the previous locks were capable of handling.
context_section_description: 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 precaution against this is provided by doubling the gates at both ends of the upper chamber in each flight of locks; hence, there are always at least two gates in each flight of locks that would have to fail to allow the higher level of water to pass downstream. The additional gates are 70 ft (21 m) 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 of 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 weighing 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 that 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 retired in the late 1980s, and today, no emergency dams are in place.
caption: Fender chain (circa 1938)
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