North jetty at Barra do Douro
Fernando Silveira Ramos
Secil – Companhia Geral de Cal e Cimento, SA and the Order of Engineers made the Secil Civil Engineering Award 2009 to the North jetty at Barra do Douro, a work designed by the engineer Fernando Silveira Ramos. This award, recognized as the most prestigious Portuguese engineering prize, every two years recognizes the most significant solution in concrete-based engineering for the two-year period in question.
The prize-winning work is a structure on the north bank of the mouth of the Douro river built so as to resist the direct action of storm waves and the currents of major floods. The work involves 65,000 m3 of concrete and 2,500 tons of steel.
For the engineer Fernando Silveira Ramos, winning the Secil Award, which for him is the “Nobel prize for engineering in Portugal”, , was a source of great pride, as the prize-winning work required “more than 10 years’ work and struggles, but mainly struggles”and he emphasized also “the specific difficulties of an ambitious programme that combined hydraulic, sedimentary, structural, landscaping, navigation and urban development requirements”.
The prize-winning architect is keen to emphasize that this was “collective work” implemented by “a cohesive and interdisciplinary technical design team” and noting that the flagships of this project were “victory of imagination and innovation in engineering work over the usual grey, repetitive pragmatism”, and the “transformation of the ‘strong, ugly’ coastal jetty into a high-quality urban facility for public use”.
Fernando Coutinho da Silveira Ramos was born in Lisbon in May, 1941 and graduated in Civil Engineering at the IST in 1966. He started to work, when still a student, at the Civil Engineering Laboratory’s Hydraulics Service, where he worked as a senior technician from 1967 to 1972.
From 1972 he began work in the Consulmar studies and design company, in the areas of coastal and port engineering, with management responsibilities in 1981.
He has been involved in and managed the development of many important and creative port and coastal studies and designs, such as the reconfiguration of the ports of Viana do Castelo, Figueira da Foz, Aveiro and the Sines liquid and dry bulk terminals. He was coordinator of the Strategic Development Plan of the Port of Lisbon which recommended the reconfiguration of the Alcântara Terminal and the use of river container traffic.
Other works that are noteworthy for their specificity are the studies that led to the registration in 2002 of a National Patent in the field of structures for the construction of non-reflective marine works, to be built inside harbours (structures already implemented in the fishing port of Afurada and the multi-functional terminal of the Port of Leixões).
His continued professional activity in the fields of maritime hydraulics, coastal engineering and port facilities earned him the 2009 award of the “Fernando Abecasis” Prize by the Portuguese Delegation of Pianc (Permanent International Navigation Congress) for career excellence.
He has always been highly active in business organizations including as a member of various bodies of the APPC (Portuguese Association of Designers and Consultants), having been elected its President in 1998 and re-elected successively in 2001 and 2004.
Fernando Silveira Ramos has combined and harmonized his professional, business and associative activities with his social and political activity from his student days to the present.
In recognition of this professional, business, associative, social and political activity, he was honoured in 2005 with the rank of Grand Officer of the Order of Agricultural Commercial and industrial Merit, conferred on him by His Excellency the President of the Republic, Dr. Jorge Sampaio.
A remarkable work
The Barra do Douro North Jetty is part of a series of works at the mouth of the estuary whose hydraulic and sedimentary coherence and behaviour are crucial to its success. Some concepts of environmental sustainability and urban and recreational use of this maritime facility have also assumed special importance in some of the chosen options.
The studies, designs and works were performed following an international design / construction competition, supervised by an independent technical committee with the selected solution validated by small-scale mathematical tests at the National Civil Engineering Laboratory.
With the IPTM Institute for Ports and Maritime Transport, I.P. as the Main Contractor, the general design of the work on the Barra do Douro was managed by a design consortium led by the Engineer Fernando Silveira Ramos, while the development of the North Jetty project was managed by Consulmar – Projetistas e Consultores, Lda. The construction work was carried out by Construtores dos Molhes do Douro-ACE (Somague Engenharia/Irmãos Cavaco) and supervised by DHV-Tecnopor / DHV-Fbo.
The main objectives of the work on the Barra do Douro were to improve the safety of vessels in the Barra channel, by protecting the shore areas of Cantareira and the Passeio Alegre from the destructive action of waves and currents and to facilitate the self-cleaning of the channel, by reducing the effort of maintenance dredging.
These objectives were to be achieved by focusing on minimizing the environmental impact on the Cabedelo and S. Paio Basin and the visual impact of the work on the adjacent urban areas and contributing to the stability of the Barra do Douro downstream beaches.
The work was implemented using several prefabricated reinforced concrete parts, cofferdams and pre-cast frames, notably with execution by sliding, on a floating dock inside the Port of Leixões, 16 large cofferdams, some about 26 x 15 x 15 m.
These cofferdams were transported one by one by flotation on the open sea for about 5 kilometres. They were then sunk on the site, on a base put in place by divers, with strict arrangement by juxtaposition and sealed against the rocky bottom to form the infrastructure of the North Jetty. Together with the section constructed of pre-cast frames, its final length is half a kilometre.
This infrastructure was further reinforced and completed, on the site, with a concrete superstructure, whose interior has a molded technical gallery, located immediately below the crown of the Jetty, which ensures access to the Lighthouse in bad weather conditions.
The selected solution enabled the creation of pedestrian walkways connecting the head of the new Jetty to the Passeio Alegre. One, on the upper level of the structure, can only be used in good weather, while the other, lower down, along a technical gallery equipped with beams over the inlet channel, can be used when the sea is choppy. These circuits are connected to one another at one end by the interior of the lighthouse and at the other end, by the base of the jetty.
The solutions from the beginning were very creative and innovative on all project development fronts and were translated in the concepts and details, in the technology, urban integration and environmental sustainability.
These features were especially evident at two stages. First in the collective and creative general design work (preparation of the design / construction competition) and then in the rigorous, innovative and multidisciplinary work of development of structural and construction solutions, with special reference to underwater work.
General Characterization of the Work
The main objectives of the work on the Barra do Douro were:
- To facilitate self cleaning in the channel, reducing the effort of maintenance dredging;
- To improve safety conditions on the vessel mooring jetty;
- To protect the shore areas of Cantareira and the Passeio Alegre from the destructive action of waves and currents.
These objectives were to be achieved with the following concerns in mind:
- To minimize the environmental impact on Cabedelo and the S. Paio Basin;
- To minimize the visual impact of the work on the adjacent urban areas.
Technical concepts and characteristics of the works:
The North Jetty is part of a body of work whose coherence and hydraulic and sedimentary behaviour are crucial to its success and whose technical characteristics were initially established as follows:
- The North Jetty is built straight to minimize its visual impact which, in conjunction with the South breakwater, will ensure greater navigational safety and reduce wave impact on shore areas;
- The South Breakwater, which is separated from the shore, conveys the Cabedelo forward and resumes locations closer to its historical configurations, retaining it with a naturalized image and reducing the height of the dunes on its inside face;
- The Cabedelo reinforcement work, which is partially submerged, at the junction with the detached breakwater, is used to support the dunes and to prevent sand invading the channel;
- The reconfiguration of the Access Channel against a North Jetty, founded on rock, provides a guarantee against undermining by powerful ebb currents and minimizes the effort required in regular maintenance dredging.
These initial design concepts later proved to be crucial for the technical structural options, as was clearly the case of the North Jetty.
Construction Materials and Processes in the North Jetty
A structure was therefore proposed, designed and built on the north bank of the mouth of the Douro river in such a way as to resist the direct action of storm waves and the currents of major floods. The work involves 65,000 m3 of concrete and 2,500 tons of steel.
The work was implemented using several prefabricated parts, cofferdams and pre-cast frames and, notably with execution by sliding, on a floating dock inside the Port of Leixões, 16 large cofferdams, some about 26 x 15 x 15 m.
These cofferdams were transported one by one by floating them on the open sea for about 5 kilometres. They were then sunk on a base put in place by divers, with strict arrangement by juxtaposition and sealed against the rocky bottom to form the infrastructure of North Jetty. On completion, together with the section of pre-cast frames, it is half a kilometre long.
This infrastructure was further reinforced and completed, on the site, with a superstructure whose interior has a shaped technical gallery, located immediately below the crown, which ensures access to the Lighthouse in any weather conditions.
The selected solution enabled the creation of pedestrian walkways connecting the Jetty to the Passeio Alegre. One, on the upper level of the structure, can only be used in good weather, while the other, lower down, along the technical gallery, which can be used when the sea is choppy. These circuits are connected to one another at one end by the interior of the lighthouse and at the other end, by the base of the jetty.
The solutions from the beginning were very creative and innovative on all project development fronts and translated in the concepts and in the details, in the technology, urban integration and environmental sustainability. These features were especially evident at two stages. First in the collective and creative general design work (preparation of the design / construction competition) and then in the rigorous, innovative and multidisciplinary work of development of structural solutions.
IPTM – Institute for Ports and Maritime Transport, I.P.
Eduardo Martins – Economist (Director – General Coordination)
Francisco Lopes – Civil Engineer (Director)
Amaral Coutinho – Civil Engineer (Local Representative)
Ludgero Gonçalves (Local Representative)
ACE – MOLHES DO DOURO consortium
Rui Vieira de Sá – Civil Engineer (Somague Engenharia – General Coordination)
Eduardo Gomes – Civil Engineer (Irmãos Cavaco – General Coordination)
Paulo Cruz Ferreira – Civil Engineer (Somague Engenharia – Work Coordination)
José Mota Fraga – Civil Engineer (Somague Engenharia – Work Coordination)
CONSULMAR – Projectistas e Consultores, Lda.
Fernando Silveira Ramos – Civil Engineer (Steering and Coordination)
Carlos Abecasis – Civil Engineer (Project Coordinator)
Alexandre Ferreira da Costa – Civil Engineer (Project Director and Works TA)
Pedro Martins – Civil Engineer (Structures)
Lucília Luís – Civil Engineer (Coastal Engineering)
Miguel Robert – Civil Engineer (Maritime Hydraulics)
José Manuel Morim de Oliveira – Civil Engineer (Project Coordinator)
Carlos Prata – Architect
HIDROMOD – Modelação em Engenharia, Lda.
Adélio Silva – Civil Engineer (Mathematical Modelling)
PROCESL – Engenharia Hidráulica e Ambiental, Lda.
Nuno Matos – Biologist (EIA)
Maria João Sousa – Environmental Engineer (Works TA)
NEMUS – Gestão e Requalificação Ambiental, Lda.
Pedro Bettencourt – Geologist (EIA)
DHVTECNOPOR / DHVFBO
António Alves Dinis – Civil Engineer (Coordinator)
José Joaquim Ranção Ferreira – Civil Engineer (Resident Engineer)