Alcantara Bridge

The Romans made large strides for engineering during their time.  It is impressive how many of their developments we use today.  This week, we will be looking at their Alcantara Bridge, which crosses the Tagus River in Spain.  Its name means “The Bridge” in Arabic, and has also been called Puente Trajan at Alcantara in Spanish.  Caius Iulius Lacer originally built it in 105 CE.  It has been subjected to many wars, and therefore has been reconstructed numerous times throughout the years.  It has lived up to its inscription, which translates to “ who will live (the bridge) so much as the world would live”.


The bridge was commissioned from Roman Emperor Trajan in 98 CE.  Construction didn’t start until 104 CE.  His honor was shown through a triumphal arch in the center and a temple at one of the ends.  No mortar was used in the original construction.  It was fit together with the rope technique.  There are also metallic staples used in the lower part of the pillars for additional stability.


The bridge is 616 feet long and 26 feet wide.  There are 6 arches supported by five pillars and two supports at the ends.  The two middle arches have a span of 150 feet.  On top of the bridge the triumphal arch is about 46 feet high.


The Alcantara Bridge has been damaged a few times in order to protect the city of Alcantara from possible attacks during wars.  One arch was destroyed in 1214 by the Moors and was rebuilt in 1543.  Another was destroyed by the Spanish and repaired in 1762.  Then the Spanish destroyed it again to protect against the French in 1809.  It was repaired in 1819, and reinforced in 1860.  In 1969 the pillars were repaired in order to withstand the new pressures caused by the Dam of Alcantara.

In the 18th century, the Torre del Oro (Golden Tower) was built for defense.  It over looks the bridge.


Visiting the Alcantara Bridge is one of the many things you can see on a trip through Spain.  The city of Alcantara is on the Spanish- Portuguese border, commonly referred to as the Raya.   You can get a taste of the ancient with the bridge as well as enjoy the beautiful scenery of forest that surrounds the reservoir.  In town you must view the paintings of Luis Morales on many of the religious temples.  Spain came into wealth with the discovery of the Americas and therefore they were able to adorn their buildings very beautifully.  When you are finished sight seeing, you can hike, horseback ride, fish, or partake in water sports.

While I have been to Spain before, learning about this bridge and the rest of Alcantara has proven to me I must go back.  There is a lot to see and do in Spain, and I would definitely recommend planning a trip trying to experience as much of the country as possible.


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4 Responses to Alcantara Bridge

  1. stephanieflee says:

    It is amazing how mankind is able to build such large structures that last so long. I always find it interesting how past civilizations were able to build bridges without the tools we have today. I cannot imagine calculating the forces in the bridge and the total cost of materials without a computer.

    Also, could you explain in more detail what rope technique is?

  2. joekuhn93 says:

    I just love the way that bridges and many other forms of structures were created back in the day when technology and measurement devices were not as precise and efficient as they are today. The amount of Civil Engineering that goes into making a bridge is beyond my imagination. What I really liked about your blog this week was the fact that you included the history of the bridge and how it has survived (for the most part) over time. Millions of cars will travel over this bridge. How does a bridge like this one remain static and withstand the thousands of pounds of force each day? Are there any statistics to back up the maximum load that this bridge can take before it could have structural failures? How long is this bridge estimated to last until it needs reinforcement and rebuilding?


  3. jaclynckrogh says:

    The arch is a remarkable element that makes this bridge possible. I don’t know the exact numbers, but the bridge can handle twice its own weight. There is no current prediction for future reinforcement. I believe it is holding up well today.

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