́ report Bridges of iron Joaquín Cárcamo Martínez Surveyor TICCIH Spain and the Basque Industrial Heritage & Public Works Association The Isabel II bridge in Bilbao in 1876. Photo: Museo Vasco de Bilbao spanning 45 metres, the Seville bridge was part of a project presented in 1844 by French engineers Ferdinand Bernadet and Gustave Steinacher, who started construction work in December 1845 after winning the contract from the City Council. Building work ran into major difficulties in the following years, until the Ministry of Public Works took over, appointing Spanish engineer Canuto Corroza to the job in 1851. Corroza finished the bridge in early 1852. In 1918, the Seville bridge’s original deck was replaced after being damaged by the increased loads it had to bear. The bridge held up until 1958, when it was closed to lorry and bus traffic. A few years later, a lively debate broke out in the city when the possibility of demolishing the bridge was mooted. However, in 1977 local engineer Juan Batanero superposed a self-supporting deck on the cast iron arches. Although destroying the structural essence of the bridge, the measure guaranteed it would remain in use, preserved the look of the bridge and maintained the original features. In Europe (and in fact the world), cast-iron bridges were a British monopoly from the construction of the original ‘Iron Bridge’ in Coalbrookdale until approximately 1850. After The re-used spans of the Bilbao bridge over the river Udondo at Lejona The Isabel II bridge in Seville today with similar bridges, it is probably deeply fissured, in which case it will need some intensive rehabilitation work. The Basque Industrial Heritage & Public Works Association has asked the Basque regional government to declare the bridge a monument, given its historical importance, particularly as Bilbao lost virtually all its city bridges when they were dynamited in 1937, during the Spanish Civil War. Until now, the only remaining bridge in Spain with a cast-iron structure was assumed to the Isabella II bridge (also known as the Triana bridge) in Seville. Indeed, the Seville bridge is the best surviving example of a type begun by French engineer Polonceau in 1834 when he built the sadly long-since disappeared Carrousel bridge in Paris. With three arches all this date they were also widely developed in France, up until the end of the 19th century. One final point. Although both bridges were cast in Spain, one by the Santa Ana de Bolueta foundry in Bilbao and the other by the Narciso Bonaplata foundry in Seville, the technology did not catch on. The use of iron, which gradually imposed itself from 1850 on, was popularized by foreign firms until towards the end of the century, largely because of the weakness of the national iron and steel industry and despite the high technical level of Spanish civil engineers. Contact: jcarcamo@telefonica.net Translation: Mark Gardner 2009 A tail of two Spanish cast-iron bridges 3 number 44 As Bilbao in the Basque Country, Spain, began to grow, its two bridges become inadequate: the old bridge of San Antón and the San Francisco chain suspension bridge by architect Antonio de Goicoechea (1827, the second built in Spain). The process of building a new bridge began with the presentation of a plan by the same architect at a city council meeting on 20 May, 1844. Spain’s Ministry of the Interior later imposed a series of technical conditions concerning abutments and piers. Above all, the Ministry insisted that the central arch be raised. Construction work on what was originally known as the Isabella II bridge began in mid-1845. It was under the provisional direction of Goicoechea until Pedro Celestino Espinosa, appointed by the Corps of Civil Engineers, arrived to take over. The bridge was not opened until January, 1848. The four cast-iron arches, each spanning 11 m over the river, and the mobile central section rested on stone piers and abutments. Each arch comprised six heavily-braced ribs consisting of a lower arch (the arch is best suited for cast iron, which basically resists compression) formed by five I-beam section segments assembled and jointed with transversal braces, an upper beam to support the deck and a succession of three circular rings of varying diameters in each spandrel, tangential to both parts and mutually braced by tie rods. In subsequent years the condition of the bridge deteriorated, particularly in 1874 when Bilbao came under siege during the third Carlist civil war. Bombs and the work of the river left the bridge unusable and it was rapidly replaced. Construction work on the new stone bridge lasted from 1875 to 1878 and was the work of the liberal engineer Adolfo de Ibarreta. Until recently, all traces of the bridge were believed to have disappeared completely. However, not long ago I had the opportunity of examining a small road bridge with a single, 11-metre arch spanning the mouth of the Udondo, a tributary of the Bilbao river estuary. The Udondo flows into the estuary at Lejona, not far from the port of Bilbao and the famous Transporter Bridge at Portugalete. My examination led me to the conclusion that the arch was in fact one of the original arches of the bridge in Bilbao. In 1876, an engineer called Pascual Landa, Head of Public Works, asked the Bilbao City Council for permission to use one of the arches to reconstruct the small bridge dynamited by the Carlist troops. For the last 133 years, the arch has remained in use, “hidden” from public view. Some decades ago, the road was widened and another, modern bridge of pre-stressed concrete beams was attached upstream to the old one. The cast-iron bridge lacks the original deck, the present one being a reinforced concrete slab. Despite remaining in service on a road currently owned by the Port of Bilbao and with heavy daily traffic, the metal structure appears to be in good condition. However, as