• Location: North-western main roads (Spain) SEE MAP
• Scope of works: Detailed inspections using special equipment of medium-long span bridges.
• Client: Ministerio de Fomento (Spain)
• Date: 2009 – 2010
• Number of structures: 65
• Main feature: detailed inspections of bridges with medium-long spans and up to 150 m high

In 1999 the” Ministerio de Fomento” in Spain initiated the implementation of an inspection program of the bridges of the main road network (the R.I.G.E). Some problems were detected concerning the reliability of the results of the inspections of some bridges, mainly those bridges where the piers were very high or bridges crossing important rivers. Some elements of these bridges could not be inspected, so the inspection was not completed.

In order to solve this problem Torroja Ingeneiría S.L. was selected by the “Ministerio de Fomento” in 2009 to carry out the detailed inspection using special equipment of 65 bridges in the north-western region of Spain.

The 65 bridges selected are located on the main roads of North–western Spain. Some examples that stand out are: the bridges of “Paso de Piedrafita on the A6 motorway, the most emblematic being the Samprón Viaduct (main span length = 140 m and highest pier = 150 m), the viaducts on the A-52 near Puebla de Sanabria, “Paso del Padornelo” and “Paso de la Canda” having more than 12 long spans as well as the famous Arch over the Ricobayo Reservoir (N-122 road). The structural schemes of the inspected bridges were varied: precast prestressed concrete beams, steel arches, composite concrete – steel continuous girders, prestressed concrete box section continuous girders, balanced cantilever bridges, and “special bridges” as is the Río Mente Viaduct on the A-52, with inclined struts installed at the piers, where precast girders are positioned.

Using special equipment all elements of these bridges could be inspected, despite their accessibility, location or height. A special mobile platform was used for exterior inspection, so some temporary traffic deviation was necessary to install the platform on the correct side of the road to be inspected. This platform was used in some situations for accessing inside some box section girders and to do an interior inspection. The technical staff were equipped with a tablet-pc, so all the data about observed damage was directly added to the bridge management system. Special lightning equipment was used for the interior inspections.

Finally, underwater inspections were carried out, in order to observe the foundations of some bridges. These inspections were done by specialized divers.

The technical staff responsible for these inspections were composed of 4 Civil Engineers and 4 Technical Engineers. Every bridge was inspected by a two-person team. If the interior of the bridge was visible then two teams inspected the bridge simultaneously, one the interior and the other the exterior surface.

Below you can find a brief summary of some noteworthy facts concerning the inspections.

65 bridges inspected.

According to their structural scheme: 31 continuous concrete box section girders, 24 precast prestressed concrete girders, 2 composite concrete – steel box section decks, 4 continuous concrete slabs, 3 special continuous concrete slab decks, 1 steel arch bridge with composite deck.

According to their location: 29 on the A-52 (Zamora – Ourense), 19 on the A-6 (León and Lugo), 6 on the A-11 (Zamora), 5 on the N-630 (Zamora), 4 on the N-VI (Lugo), and 2 on the N-122 (Zamora).

472 spans, with varying span length from 20 to 175 m; average: 7,3 spans / bridge.

Inspected bridges total length = 20500 m; average: 315 m / bridge

Inspected bridges total area = 312000 m2.

Efficiency of the inspection platform: 5-7 spans / day

12000 observed damages introduced into the bridge management system; average 180 damages / bridge

9 underwater inspections