On June 25, 1906 the Congress of the United States adopted the construction of a Lock canal, having a fresh water lake with a summit at 25.9 meters, as recommended by the minority report of the Board of Consulting Engineers convened by the US president one year before, the majority of the Board recommended a sea-level canal. The Panama Canal is the only infrastructure in the world that raises 27m oceangoing ships from one ocean, allows them to navigate in a freshwater lake and then lower the vessel at the other end again to sea level, using an average of 220,000m3 of freshwater for each of the about 14,000 ships that use the canal every year.
At the time of preliminary plans, excavation works within land had a leading concern than the dredging works at the sea entrances and lock structures. However, given the construction technology and machinery available most of the locks construction were performed between February, 1910 and June, 1913.
In a paper released on October 1, 1915 written by Richard H. Whitehead is very well described the process of designing the “Hydraulics of the locks of the Panama Canal”; furthermore, there are many details of after built tests that the author compares with the design data, he also sheared the alternatives considered during the design process. The performance of the US built locks in Panama is a success case study that is beyond the purpose of this paper, about 1,050,000 seagoing vessels have transited the Panama Canal in the last 103 years.
In this paper we are going to focus on the process for formulating the conceptual hydraulic designs for the new locks of the Panama Canal that started operations in June 26, 2016. These conceptual design works were performed by Consorcio Post Panamax (CPP) in cooperation with personnel from the Autoridad del Canal de Panamá (ACP) between 2002 and 2008. CPP had the experience of designing and constructing large locks in Europe whereas ACP had the experience of operating and maintaining for almost a century the US built locks.
Amongst the main criteria that ACP asked to consider were the Gatun Lake water quality, number (lifts) and size of lock chambers, type and size of lock gates, water saving, Filling and Emptying system, electromechanical systems, vessel positioning systems, earthquake loads, constructability, operations, costs and chronological estimates, etc. CPP organized visits to some large locks in Europe for gathering performance and lessons learned from these locks that had several similarities with the locks that ACP was forecasting to design as per the market studies and build given the country financial opportunities.
The conceptual hydraulic designs for the new locks Filling and Emptying (F/E) System of the US built locks designed by Whitehead was very innovative last century and also considered features from other locks built in the US and Europe, the system worked very well and it was a challenge to come up with a better one. Within the companies of CPP, Compagnie National du Rhone (CNR) was in charge of the hydraulic design. All of the parameters mentioned above, with the most important: water conveyance from Gatun Lake and/or from Water Saving Basins (WSBs) as well as wind, Lake seasonal elevations and hourly tides, F/E times, vessels throughput and operating possibilities were taken into account.
A very important apprehension that ACP had was to break the paradigm of using locomotives atop the lock walls for vessel positioning aids; hence, it was a challenge to come up with an F/E system that would have the symmetry, evenness and swiftness to achieve a safe raising or lowering of a ship in a lock chamber.
CNR started to study the hydraulics of the US built locks and several other locks worldwide in order to gather important aspects for the final design and issued relevant design criteria for the Panama Canal New Locks since they would be the first on-sea going vessels locks equipped with WSBs in the world. A first issue raised by ACP was the possibility of having an F/E system with water entries and exits from the sides of the lock chamber, for the system with lateral culvers and F/E from the bottom of the chamber represented a maintenance concern for ACP, another issue was the fact that placing the WSBs to one side of the lock chambers (for saving space at the other side for the 4th lane of locks) created an inherent asymmetry to the system.
During a conceptual design phase, several configurations were investigated including 1 lock equipped with 6 WSBs, 2 locks equipped with 2 & 3 WSBs and 3 locks equipped with 2 & 3 WSBs.
A preliminary design of the – 3 steps locks & 3 WSBs – retained solution was then carried out including implementation of 2D/3D numerical models and the construction of a Physical Model at scale 1/30 for validating the F/E system hydraulic performances and giving ACP results with enough confidence to release Employer Requirements with respect to hydraulic issues.
After a Design & Build tender process, awarded to the consortium GUPC, CNR did carry on participating in the final hydraulic design. A hybrid modelling methodology was implemented since both 1D/2D/3D numerical models and a second physical model at scale 1/30 were run jointly during one year. These models incorporated the fews changes proposed by the contractor to the initial conceptual design. The hybrid model permitted to correct unexpected problems, to optimize the design of few components of the F/E system and to issue accurate data with respect to hydraulic performances of the system.
On-site tests were carried out in the beginning of 2016 in order to check that the expected performances were achieved. To a certain extent, these tests were the final end of a 16-years study that allows to successfully inaugurate the New Locks in June 26, 2016.