The mountain highway from Valea Oltului, under construction for two years. How the great viaducts and tunnels were worked
The Valea Oltului highway has been under construction for two years, but no viaduct has been completed, work is underway on two of the seven tunnels, and construction permits are still awaited for a large part of the 31-kilometer route between Boita and Cornetu.
Boita Tunnel. Photo: Daniel Guță. TRUTH
Two years have passed since the start of work on the mountain highway that will cross the Olt Valley, connecting the historical regions of Transylvania and Muntenia. The construction site opened in 2024 in Boita, Sibiu county, has gradually expanded, but the works are far from finished.
Only a third of the more than 120 kilometers of the A1 Sibiu – Pitesti Highway have been completed so far, and its most difficult segments have been under construction for about two years, between the localities of Boita, in Sibiu County, and Curtea de Argeș.
The route of the highway that will cross the Carpathians through the Olt Valley was divided into five sections, for which the Romanian state and the builders signed design and execution contracts in the period 2019-2022.
In recent years, the sections Sibiu – Boita, 14 kilometers long, and Curtea de Argeș – Pitești, 30 kilometers long, have been opened to road traffic. Another 10 kilometers of the Sibiu – Pitesti Highway, between Tigveni and Curtea de Argeș, have a completion date of 2026, with the physical stage of the works exceeding 90 percent.
On the most difficult sections of the mountain highway, Boita – Cornetu, 31 kilometers long, and Cornetu – Tigveni, 38 kilometers long, the works are still at the beginning, and the completion dates are 2028 – 2029.
The new highway on Valea Oltului represents, along with the Holdea – Margina section, 13.5 kilometers long, in western Romania, one of the last unfinished segments of the A1 Nădlac – Bucharest Highway, the longest highway in Romania, with almost 600 kilometers.
Two years of work at Boita
The works on the most complex lot of the mountain highway started in the spring of 2024, in the Sibiu town of Boita, located at the entrance to the Olt Valley, through the Turnului Roșu gorge.
The contract for the construction of section 2 Boita – Cornetu, 31.33 kilometers long, was signed in February 2022 and assigned to the association Mapa Insaat Ve Ticaret AS – Cengiz Insaat Sanayi Ve Ticaret. The value of the works was estimated at 4.250 billion lei, without VAT, and the contractual term provided for 18 months for design and 50 months for execution, i.e. the completion of the lot by the end of 2027. Further estimates aim for its completion in 2029.
It was only in April 2024 that the Ministry of Transport issued the first construction permit for a sector of approximately one kilometer of the highway, in Boita, where, shortly after, work began on the first viaduct on the Oltului Valley.
“It is about the Boita area, where a viaduct similar to the one on Section 1 (the Tălmăcel Viaduct) will be built, approximately 600 meters long — a very spectacular work of art — and another portion of embankments”informed then Cristian Tudor, from the Regional Directorate of Roads and Bridges Craiova.
For over a year, the builders of the Boita – Cornetu section could only work on the segment at the entrance to the gorge. Only in the summer of 2025, after the issuance of a new construction permit, four other viaducts came into operation, in addition to the one in Boita, the construction site being extended by 4.5 kilometers.
It was also then that work began on the 900-meter Robești Tunnel, the construction site being thus extended by approximately one kilometer, through a new authorization. At the beginning of 2026, three more viaducts and the Boita Tunnel, approximately 270 meters long, entered the construction site, the route currently being worked on in the Olt Valley is approximately six kilometers long.
The huge construction site at Boita
The stage of works on the highway section on the Olt Valley has exceeded eight percent, according to the Center for Technical Road and Informatics Studies (CESTRIN), within the National Road Infrastructure Administration Company (CNAIR).
None of the viaducts under construction at Boita has been completed, although the stage of work on the first five viaducts has exceeded 50 percent, CNAIR officials recently informed.
However, the area at the entrance to the Turnu Roșu gorge has undergone extensive transformations in recent years. The pylons and superstructures of the viaducts have been erected, and Turkish builders are adding the final beams to some of them. At the entrance to Boita from Sibiu, work has begun on the Boita motorway junction, which will connect the A1 Sibiu – Pitesti motorway with the A13 Sibiu – Făgăraș motorway and DN 7 Sibiu – Râmnicu Vâlcea.
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The Boita interchange, which will be built on three levels, is part of the 14-kilometer section I Boita – Avrig of the A13, with a completion date of 2028. The entire Sibiu – Făgăraș highway, with a length of about 70 kilometers, is under construction, with its completion expected in 2028.
The Boita tunnel, the first tens of meters excavated
On the edge of Boita, towards the gorge, excavations have recently begun at the second gallery of Tunnel I Boita.
“Currently, the works are also progressing at a good pace on the Boita 1 tunnel, consisting of two galleries of 264 meters, on the Sibiu-Pitesti direction, and 247 meters, on the Pitesti-Sibiu direction. The first 22 meters of the left gallery, on the Pitesti-Sibiu direction, have already been excavated, and work is underway to consolidate the entrance and exit portals”. recently informed Cristian Pistol, director of CNAIR.
Seven tunnels will be built on the Boita – Cornetu segment, from Valea Oltului. Two of these, one of 270 meters and another of 360 meters, will be built in the area of Boita, at the entrance to the gorge, on the right side of the valley.
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Sibiu Pitesti highway, Boita construction site Photo Daniel Guță THE TRUTH (15) jpg
“On the route of Section 2 Boita-Cornetu of the Sibiu-Pitesti highway, seven road tunnels will be built, with a total length of approximately five kilometers, as well as 24 bridges and 24 viaducts, with a total length of approximately 11 kilometers”, added Cristian Pistol.
Two other tunnels, with a total length of approximately 1.39 kilometers, one of them exceeding 1,000 meters, will be built in the Lazaret area, on the left side of the valley. In the same area, an ecoduct will be built over DN 7, the Olt River and the Olt Valley railway.
Another tunnel, 1.6 kilometers long, will be built west of the town of Câinenii Mari, on the left side of the gorge. In the area of the hydropower development from Robești, the route will cross the slope through a tunnel of approximately 900 meters, located in the construction site, followed by another tunnel, of approximately 455 meters.
The most complex highway interchange is taking shape. “It will have numerous bridges, passages and even viaducts, on three levels”
The first gallery of the Robești Tunnel, pierced
In Robești, on the other segment under construction on the Valea Oltului highway, the construction progress of the Robești tunnel is approaching 32 percent, according to CNAIR. On May 5, the first gallery of the tunnel, with a length of over 900 meters, excavated with the help of explosives, was pierced.
“The teams of tunnel specialists of the Turkish builders' association Mapa-Cengiz managed today to break through the first gallery of the Robești tunnel, 900 meters long, on the Pitesti-Sibiu direction. From the second gallery, on the Sibiu-Pitesti direction, about 113 meters remain to be excavated, until the breakthrough is achieved”, informed, on May 5, Cristian Pistol, director of CNAIR.
According to the CNAIR official, after both galleries have been pierced, the builders will start assembling the formwork for the execution of the inner lining.
The two mountain sections of the Sibiu – Pitesti Highway, which cross part of the Olt Valley and the Băiaș Valley, present a high technical difficulty, which forces the builders to apply a series of complex engineering solutions, CNAIR says.
After completion, the mountain section will provide a high-speed road connection on the East-West axis, between Banat, Transylvania, Muntenia and Dobrogea, for approximately 850 kilometers.
