As of the closing of this issue, we are immersed in the greatest health crisis in recent history. An unprecedented event that is forcing us to adapt, change how we work and bring out the best in ourselves. I want to express my solidarity and appreciation to everyone with the firm conviction that together, we will overcome it.

Nevertheless, our dedication and commitment to the improvement of mobility and safety of infrastructure, spurs us on to continue carrying out our activity. One example of this is the comprehensive renovation of the Recoletos tunnel, which traverses Madrid from north to south and is a key element in improving the comfort and safety of this infrastructure, which carries the most rail traffic of the entire Spanish network. Designed and managed by Ineco on behalf of Adif, our technicians have played a crucial role in tackling one of the most important railway mobility projects in little more than five months, given that several commuter lines run through this tunnel, serving more than 250 million passengers a year.

Knowledge and input for improving urban mobility and promoting its sustainable development were combined at the recent World Urban Forum in Abu Dhabi. With the objective of facing the future with more sustainable and inclusive transportation, the companies of the Group of the Ministry of Transport, Mobility and Urban Agenda presented their innovative projects at this international meeting convened by UN-Habitat.

Our dedication to improving the safety of transport and mobility has led us to participate in important studies and projects with major social benefits

Experience in the modernisation of railway lines, and in particular in the development and deployment of the ERTMS system, together with more than 14 years of collaboration in European innovation projects, led to Ineco’s participation in ERSAT GGC, an ambitious project financed by the European Satellite Navigation Agency which will make it possible to implement satellite technology in the European rail traffic management system ERTMS by means of virtual balises.

This same dedication to innovation to improve air and land safety is also behind the efforts by our experts to develop the ‘Factor Humano’ methodology, which has received several different awards, including the Canso ‘Global Safety Achievement Award 2019’.

Ineco’s international activity also prompted its involvement in the supervision of new trains for Quito’s first metro, and in the aeronautical field, to the design of the Master Plans for 12 airports of the Pacific Airport Group, a client to whom we are grateful for the comments made by its Network and Regulated Business Director, Jose Ángel Martínez.

As for Spain, in this issue we cover two road projects recently opened by the Ministry of Transport, which will reduce travel times and increase safety levels: the complex stretch of the A-23 highway as it passes through the Monrepós mountain pass, and the new Gaznata bridge over the Burguillo reservoir in Ávila.

Lastly, we highlight the launch of Ineco’s new Equality Plan, which includes important initiatives aimed at achieving real and effective equality, and which will have a Monitoring Committee to measure its degree of implementation and impact.

Floating on the waters of the Burguillo reservoir, and later hoisted into position to connect the two cantilevered end sections: this was how, last July, the central steel box girder section of the new La Gaznata bridge in Ávila province was installed. The bridge, now completed and opened on 28 November, 2019, represents a notable improvement in mobility and safety for the 5,000 road users whose daily travel takes them past kilometre 100 of the N-403 road, which spans the provinces of Toledo, Madrid, Ávila and Valladolid. Access to the bridge has also been improved by a new roundabout to smooth the horizontal alignment. In total, the works covered almost a kilometre.

Ineco provided technical assistance services for the supervision and monitoring of the works for the General Directorate of Roads and the Ministry for Transport, Mobility and Urban Agenda. At 11 metres wide and with one lane for each direction of travel, the new bridge replaces the narrow crossing offered by the old arched bridge, whose single carriageway measuring just 4.5 metres wide meant that users had to take turns crossing from each direction.

The structure, however, which was designed and constructed in the 1920s by engineer Eugenio Ribera, is of both historical and technical significance as one of the first bridges to be built in Spain using reinforced concrete, which was just coming into use in the country at that time. The bridge was later used as a construction model for other viaducts and is an excellent example of the construction techniques at that time. Its closure to traffic will therefore ensure its preservation. Alongside it, the new, partially prefabricated straight bridge made from prestressed concrete and steel epitomises the construction techniques of today, and the combination of the two structures, separated by a distance just a few metres but 100 years in time, perfectly illustrates the evolution of Spanish bridge design and construction over the course of the last century.

The new bridge

The deck of the bridge consists of a box girder measuring 11.3 metres wide to support the carriageway, hard shoulders and parapet walls. Both prestressed concrete and Corten steel were used with the incremental launching method from both piers towards the centre, building successive prestressed concrete segments.

The new bridge has three spans. The two ends, with spans of 40 and 50 metres (distance between the support points), support prestressed concrete box girder sections, built using falsework, with a thickness that varies between 2.4 metres at the ends and 5.5 metres above the 10-metre reinforced concrete piers. Each pier comprises two shielded shafts forming a ‘V’. The shafts rest on footings which are in turn ‘stitched’ to the supporting rock with micropiles.

The central span measures 120-metres long and is divided into three sections of two types: two outer sections made from prestressed concrete with variable thickness beginning at each pier, built using the incremental launching method, and a 42-metre long middle stretch made from concrete and steel.

One of the highlights of the project was the floating transfer and subsequent lifting of the central metal stretch of this section, which took place in July 2019. The 115-tonne segment, which had to be entirely watertight for it to float, was manufactured in the workshop and then transported to the site in two pieces measuring 27 and 15 metres.

The old bridge

La Gaznata was an old stream that has today become one of the four tributaries of the El Burguillo reservoir. It was opened in 1913 to channel water from the Alberche river. The first bridge, designed by civil engineer, entrepreneur and professor José Eugenio Ribera, who pioneered the use of reinforced concrete in Spain, was opened in 1918.

It comprises four cambered arches spanning 25 metres each, followed by five 11.5 metre straight sections (four on one side and one on the other). It was built using a rigid truss for each span, which was raised by complete spans from the ground.

The bridge is one of the concrete road bridge models designed by Ribera for the Ministry of Public Works. The designer, who died in 1936, dedicated his career to promoting the novel idea of using reinforced concrete or cement in construction and, particularly, for building bridges and viaducts. The appearance of reinforced concrete in the last quarter of the nineteenth century revolutionised construction methods. It displaced both traditional materials like the stone and wood which had been used for centuries and also, thanks to the cost-effectiveness of concrete, the metal bridges that had become popular after the Industrial Revolution.

Construction using arched structures, a practise employed since ancient times, presents the the disadvantage that structures only become self-supporting once completed. This necessitated the construction of large temporary structures, the falsework, which were almost as expensive and complex as the bridge itself.

Eugenio Ribera’s decision to build with spans measuring no more than 25 metres meant that he was able to forgo the falsework, significantly reducing costs: “… If the spans of the arches do not exceed 25 metres, as was the case with the Gaznata viaduct, we assemble each of the trusses in a single piece and raise them using rigs fitted to a mast until they are in position. (…) The elimination of falsework almost always results in significant savings in the cost of the bridge.” José Eugenio Ribera, “Masonry Bridges and Reinforced Concrete – Volume IV (Puentes de fábrica y hormigón armado – Tomo IV)”, 1932.

After 1928, the appearance of prestressed concrete made it possible to construct non-arched straight structures for large bridges, as well as for the smaller spans built from concrete before then. It also facilitated the incremental launching construction method, which eliminated the need for falsework and made concrete bridge building even more economical.

After World War Two, the new technique spread rapidly, spurred by the need to reconstruct bridges after the conflict. Since then, straight bridges have practically made arched bridges redundant. Today, we use two systems: in situ concrete bridges (which allows for different forms, curved or forked decks, etc.) and bridges made from prefabricated beams for smaller spans.