page_title: Panama Canal locks
section_title: Construction
hierarchical_section_title: Panama Canal locks / Construction
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: The construction of the locks began with the first concrete laid at Gatun, on August 24, 1909, by the Philadelphia-based company Day & Zimmermann (formerly known as Dodge & Day).
  The Gatun locks are built into a cut made in a hill bordering the lake, which required the excavation of 5,000,000 cubic yards (3,800,000 cubic metres) of material, mostly rock. The locks themselves were made of 2,046,100 cu yd (1,564,000 m³) of concrete.
  The quantity of material needed to construct the locks required extensive measures to be put in place to handle the stone and cement. Stone was brought from Portobelo to the Gatun locks, while the work on the Pacific side used stone quarried from Ancon Hill.
  Huge overhead cableways were constructed to transport concrete into the construction at Gatun. 85 ft (26 m) high towers were built on the banks of the canal, and cables of 2.5 in (6 cm) steel wire were strung between them to span the locks.  Buckets running on these cables carried up to six tons of concrete at a time into the locks. Electric railways were constructed to take stone, sand, and cement from the docks to the concrete mixing machines, from where another electric railway carried two 6-ton buckets at a time to the cableways. The smaller constructions at Pedro Miguel and Miraflores used cranes and steam locomotives in a similar manner.
  Concrete is normally moulded in formwork, temporary structures that give shape to the concrete as it sets. For a simple construction, these would normally be made of wood, but the scale of the locks demanded extraordinary forms.
  The forms for the walls consisted of towers, fronted with braced vertical sheets, 7.5 in (19 cm) thick, mounted on rails to allow the locks to be constructed in sections. A section of lock would be poured behind the form, and when it was set, the form would be moved to do the next section. Each of the twelve towers was 78 ft (24 m) high by 36 ft (11 m) wide. The forms for the culverts were made of steel and were collapsible so they could be removed and moved along after each section of culvert had set. In all, there were 33 forms for the centre and side-wall culverts, each 12 ft (3.7 m) long, and 100 smaller forms for the lateral culverts.
  The Pacific-side locks were finished first—the single flight at Pedro Miguel in 1911 and Miraflores in May 1913.
  The seagoing tug Gatun, an Atlantic entrance working tug used for hauling barges, made the first trial lockage of Gatun Locks on September 26, 1913. The lockage went perfectly, although all valves were controlled manually since the central control board was not yet ready.
caption: The main culvert forms are seen in the foreground here during construction; behind can be seen the towering wall forms.
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