Structures, water, computers, languages and people (not necessarily in this order)

A bridge for our high speed train

General view of the construction (upper image).
Reinforcement of the hinges of the arch (lower image).

The most beautiful bridge for the Galician high speed train was finished successfully and I was there, having a look and talking to our on-site partners that usually give advice to the contractor. It was concluded by laying down the two halves of the central arch last December. The bridge is placed in a rural valley close to Santiago de Compostela.

As one of my on-site colleagues explained us, the arch serves to create a fixed point to resist the horizontal braking forces from the deck. Without the arch, an enormous abutment would be necessary. Undoubtedly the arch also helps to improve the visual impact on the landscape.

Video of the lowering stage. Heigth of the arch = 80 m, Span of the arch= 120 m, Time = 2 days.

View of the deck from the ground (left). My colleagues and I having a look (right).

Building an arch bridge is always tricky since the structure is completely unstable until the two parts meet in the middle. In this particular case, the arch was cast and laid using a German cable stayed system over the head of the closest pier and tensioned from the base of the next pier. Once the two semi-arches were connected by a hinge joint at the key to form a three-hinged arch, the key and arch springs were concreted to reduce this to a two-hinged structure. Displacements of the arch and the head of the pier have been computed in a quite sophisticated way for each time step. Unfortunately, real behaviour can be more complicated than the most complicated theory and the sophisticated calculations of the deformations barely coincided with the real ones.

Usually arch bridges employ vertical supports (a.k.a. spandrels) to distribute the vertical loads of the deck to the arch below, but the Natchez Trace Bridge was designed without spandrels to create a more open and aesthetically pleasing appearance and, indeed, that bridge has strongly influenced the contemporary bridge design.

Picture from the edge of the deck.

I am confident that these infra-structures will provide positive possibilities for the residents of Galiza. New business opportunities will inevitably be created as investors from Madrid and the North West can open up new commercial ties. It is true that we Galicians/Spaniards are not a train culture but perhaps things may change if we can enjoy the fast and affordable transportation of our French and German neighbours.

Note: I did not publish this post in December due to the odd requirement of confidenciality although the process was seen from all the places of the valley and, in fact, lots of videos were recorded and uploaded by the villagers. Copying pictures without a polite acknowledgement is not allowed .


  1. Unfortunatly, I can´t agree with you this time. :( From a technical point of view, this bridge can be very beautiful indeed, but not from an aesthtetic one. As seen on the first picture, the finished bridge will appear as a huge concrete cage, a grille or a fence in the territory.
    That´s one of the reasons why I feel so uncomfortable with infraestructure development: to join to points, they divide most of the territory they cross.

  2. Of course, no bridge is perfect and this is not an exception. It could have been improved using longer spans, white concrete and more variable sections. The gap between piers was 60 m, which is not too short. A longer span would have meant a more expensive structure and public investments are always under limitations. I tried to underline that aesthetics were improved thanks to the central arch without increasing the budget (the cost of the arch saves money in the abutments) and the result is quite good as a whole.

    Not in vane, all the Galician political forces (PSOE, BNG, PP) have agreed that the impact due to the occupation of land was compensated by the positive effect on accidents and pollution reduction on the roads and the economic and social develompment of the country.

  3. "A bridge for our high speed train" or "a high bridge for our train"?

  4. Now seriously, I am surprised by your remark "It is true that we Galicians/Spaniards are not a train culture". I have family and friends in places like Pontedeume or Uxes and they used to use the train. The train is always my first choice, but in Galicia it is rarely a choice.

    I would say that for the frequencies, kilometres of tracks and quality of the service the number of passengers is outstanding.

  5. I have family and friends in (...) Pontedeume (...) and they used to use the train

    Brave are they!!!. I must admit that the service between A Coruña and Vigo can be considered among the best (65 km and 45-50 minutes of trip from Compostela to A Coruña for just 3.90 euros and departures each hour) but if you try to go from Ferrol to A Coruña by train it will be a nightmare (3.90 euros and 1 hour and 20 minutes spent for less than 60 km and only two services a day).

  6. Where it is no so funny is in samll villages like mine, Redondela, near to Vigo. In such places trains aren´t that frecuent, and it´s possible that you have three trains in an hour, and then wait two hours for the next.
    Lack of organization is the real problem with transport in Galicia. And is there where engineers are needed :), to put a little order.

  7. from Ferrol to A Coruña by train it will be a nightmare

    Hence the past tense.

  8. hay veces en que tu país subdesarrollado hace enormes esfuerzos para darte una buena educación y que seas un profesional exitoso (en lo económico y en lo personal), pero ese país confía en que los conocimientos que te entregó los usarás para el beneficio de todas las personas que los necesiten en tu país, ya que ese país está falto de ello y necesita urgente profesionales para su desarrollo...tu hablas de las condiciones para desarrollarse de una manera muy simplista que se traduce solamente en lo económico ya que una persona para desarrollarse profesionalmente no es necesario que ganes millones y millones de pesos..."un país que toma prestados unos recursos" qué estamos hablando!!! los países desarrollados se llevan los profesionales de los países subdesarrollados pq son productivos y baratos, pero es muy dificil que estos vuelvan ya que las condiciones de vida son obviamente legítimo emigrar, pero queda al descubierto la ética de la persona ya que siendo profesional en un país subdesarrollado no es sinónimo de pobreza y falta de oportunidades no? quizás no se gane tanto como en Estados Unidos o España, pero se va a tener nivel de vida mejor que el promedio y a la vez se le va a esta devolviendo la mano a tu país y a tu gente.

  9. These pictures are breathtaking! Thanks for posting them!

  10. Valeu pelas dicas!!
    Estou com essa dúvida na cabeça hoje novamente.. Está chegando a hora de fazer o TG (trabalho de graduação) e depois o mestrado e eu ainda não decidi que área seguir..