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Valdastico A31 North Motorway
In the nineteen sixties the A31 motorway was conceived to be a necessary link between the Padano – Veneto system and the areas of northern Europe, designed to connect with the A22 “Brenner Motorway” and central Italy through the Italian motorway system.
Project: A31 Trent-Rovigo motorway – Section Trent-Valdastico-Piovene Rocchette.
Location: Province of Vicenza/Independent Province of Trent, Italy.
Client: Autostrada Brescia-Verona-Vicenza-Padova S.p.A..
Cost of total Works: 1,722,247,000 €
Services: Preliminary design and environmental impact study.
This concept was to take the form of a new motorway axis joining the provinces of Rovigo, Vicenza and Trent, crossing the Padano-Veneto plains in its southern section from Rovigo to Vicenza, and the Pre-Alps in the northern section going up to the A22 motorway in Trent.
Political and economic ups and downs during the last 30 years of the 20th century only permitted implementation of the first northern section of the A31 Motorway, leaving both the connection to the south towards Rovigo and that to the North towards Trent uncompleted. The start of the new millennium also witnessed the start of works for completing the southern section which is now almost terminated. The project in question, on the other hand, specifically concerns the completion to the north.
This latter section is the most difficult to build because it almost entirely crosses a mountainous area of high naturalistic value.
Development of the A 31 Valdastico motorway to the north, therefore, represents completion of a new motorway axis that would connect with existing infrastructure axes (the A4 Turin-Trieste Motorway, the A22 Modena-Brenner Motorway and, indirectly, the A13 Bologna-Padua Motorway) and with infrastructure axes now in design phases (the Pedemontana Veneta Highway and the Nogara-Adriatic Sea Regional Motorway). It constitutes addition of an important new element in the infrastructures offered by the North-East, especially for long distance light and heavy traffic. The design difficulties regarding this northern completion of the A31 motorway become evident in this context: designing a motorway axis that must combine national and international utility while travelling in an area with strong local characteristics and an almost uncontaminated environment. The particularity of this intervention resides both in technical and technological aspects tied to construction of the works and to architectural aspects of the design solutions and the mitigation and environmental insertion works.
Alignment selection, river crossings and architectural solutions.
At the very start of design it was necessary, for the purpose of identifying the optimum alignment, to perform a comparative analysis of various alignment solutions which, starting from a common point at Piovene Rocchette (the current northern terminal of the Motorway in the province of Vicenza) connect to the A22 Brenner Motorway in 6 different points to the north and to the south of the city of Trent. Alignments were assessed comparatively, identifying confrontation parameters such as the geological, hydro-geological and hydraulic contexts, urban, archeological and environmental aspects, transportation aspects and construction site organization problems as well as financial assessments. These elements led to composition of a multi-criteria assessment matrix used to identify the best alignment.
Subsequent in-depth studies conducted on the chosen alignment led to definition of a preliminary work for this alignment as well as the Environmental Impact Study necessary to start regional and national approval procedures. The most outstanding features of the work, from the wide range of themes and problems that were faced up, are clearly that of substantial use of alignments in natural tunnels, identification and assessment of architectural solutions that maximize insertion of the work in the area context and themes regarding crossings over the river systems encountered and in particular the Adige River. The alignment, which basically connects the Valdadige with the Astico Stream Valley (Valdastico) and subsequently with the upper Padano-Veneto plains, calls for construction of a 15 kilometer summit tunnel which would become the longest road tunnel in all of Italy and which required, at the start of design, a preliminary study that aimed at identifying the best excavation method related to technical feasibility and cost. The excavation technology that was identified is mechanical excavation using Total Boring Machines (TBM), selected considering the need for rapid execution of works considering the length of the tunnel and the need to limit construction costs.
All open-air one-off structures, such as bridges, tunnel entries and toll and service areas, have architectural-structural design solutions that maximize insertion of the works into the surrounding area context and that include a single leitmotif in their architectural design concept. The Viaduct over the Adige River, located at the northern terminal end of the new Valdastico motorway where it intersects with the A22 motorway, is characterized by the span crossing the river with an arch structure carrying a 140 meter span lower deck section. This structure on the one hand gives adequate form to the point of junction of the two motorways and on the other hand softens the landscape impact by recalling architectural themes of many other works already built in the Valdadige along the A22 motorway. The architecture proposed for all the structures present at toll booths, maintenance centers, service areas and tunnel entries recalls a feature that is a natural aspect of the valley: the Astico stream with its riverbed formed of flat and rounded rocks and stones, symbolic of the natural feature of the context. These elements consequently lead to architecture that proposes, in an analogy of stones, apparent casual distribution of roof elements that remind us of their forms and colors.
The main characteristics of the work
In 2011 the Company Autostrada Brescia-Verona-Vicenza-Padova entrusted the RAETIA Consortium composed of Technital, 3TI Progetti Italia, SIS, Rocksoil, Prometeo Engineering, GIRPA, Sintel, Italtec and Hydrostudio, with preliminary design, environmental impact study and final design of the A31 Trent-Rovigo Motorway – Section from Trent-Valdastico-Piovene Rocchette. At the present time both preliminary design and the environmental impact study have been drawn up. Technital carried out general coordination of design activities, acting to integrate the different specialized services with each other and, in detail, carrying out geological and geotechnical studies, archeological studies for the purpose of prior assessment of archeological sites, transport and urban studies, design of the main road axis and the interchanges, structural design of all the open-air and underground engineering structures, design of construction sites, architectural design of buildings and design for green areas and environmental and landscape insertion works, plant engineering, identification and solution of interferences with technological lines and expropriations.
The preliminary design and environmental impact study were approved by the Board of Directors of the concessionary Autostrada Brescia-Verona-Vicenza-Padova S.p.A. on September 23rd, 2011 and by the grantor A.N.A.S. S.p.A. on February 2nd, 2012. Approval procedures by the Veneto Region, the Independent Province of Trent and the Interministerial Committee for Economic Programming (C.I.P.E.) are currently under way.
Length of the motorway route: approximately 39 kilometers from the A31 motorway existing at Piovene Rocchette up to the A22 Motorway at Besenello;
Standard section: Category A – Suburban motorway with two lanes in each direction (L=3.75 meters) and hard shoulder (L=3.00 meters).
No. 1 motorway junction with the A22 Motorway;
No. 2 motorway interchanges.