Underground engineering

State Road 284 "Occidentale Etnea"

Modernization design and arrangement of the section between km 26 and km 30
Owner/client ANAS S.p.A.
Type of service Detailed Design, Final design assistance
Location Province of Catania
Period 2017 - 2019
Cost -

PRO ITER Progetto Infrastrutture Territorio (mandatary), Delta Ingegneria (principal)

The intervention will allow a route greater linearity (currently tortuous and with numerous points of conflict determined by the entrances to various properties) and will allow to move away the road link from the urban settlements that in recent years have grown on the territory.

The Stale Road No.284 connects the Randazzo Municipality (one of the major centers of the Nebrodi Park) with the Paternò Municipality, located near Mount Etna at 256 meters above sea level. The design concerns the upgrading between km 26+000 (at the junction of a section already upgraded) and km 30+000 in correspondence of Adrano Municipality: there will be mainly off-road works and some stretches in the roadway with the carriageway upgrading to category C1 (secondary suburban) according to the Ministerial Decree of 05/11/2001.

The design layout has a plano-altimetric trend that is substantially bound to the morphology, to the needs of street functionality and to the necessary limitation of the areas to be expropriation subjected: these constraints have led to the viaduct and tunnel design, as well as large embankment sections with important works of roadway support and containment. In addition to the main axis, the design provided for the adaptation of numerous secondary roads and the construction of 3 new junctions: the most important is the 'Adrano Nord' junction whit an intersection at staggered levels construction (with 'diamond' configuration) and the insertion of two traffic circles for the traffic flows optimal management in the junction.

'Giordano' viaduct

3 spans of 60 m; mixed steel/cls structure.

'Granatallo' viaduct

4 spans of 40 m; mixed steel/cls structure.

'Cannatella' tunnel

Artificial tunnel; Length 95 m (polycentric section in reinforced concrete).

'Naviccia' tunnel

Artificial tunnel; Length 42 m (large diameter piles with cover slab).

The most significant structural works include two viaducts and two artificial tunnels. The viaducts (Giordano and Granatallo) are characterized respectively by 3 spans of 60 m and 4 spans of 40 m: both decks have a mixed steel-concrete structure composed of two main double-T metal beams of variable height, a central beam only to support the slab and a concrete slab 31 cm thick made with pre-stressed concrete. The Cannatella artificial tunnel, with a polycentric section in cast-in-place reinforced concrete, has an overall length of 95 m and is divided into four sections: the two central sections (L=32.50 m), with a constant section and divided by a water-stop joint, are characterized by a canopy thickness of 90 cm and a bottom slab height of 200 cm, while the two terminal sections (15 m each), have a flute-bill shape with a variable section. The Naviccia artificial tunnel is 42 m long and consists of large-diameter reinforced concrete piles (D=1500 mm, i=1.65 m approx.) with internal reinforced concrete structures; at the top there is a 1.60 m thick cast slab and a connecting beam. The tunnel internal height is 7.88 m.

Another characterizing aspect of the design concerns the landscape and environmental interventions planned to mitigate the structures inclusion: they have been designed and implemented with the objectives of visual levels containment, works integration with the territory, implementation of the naturalness degree (with green systems), mitigation of the works impact and compensation for the undeveloped land loss. Important naturalistic engineering works have been foreseen such as: containment works with reinforced soil, walls covering with local split stone, arrangement with a shrub belt of road relevance, tree rows arrangement, explantation and replanting of valuable trees, environmental restoration of abandoned areas, morphological remodelling (slopes affected by the tunnels construction), acoustic protection interventions (both with barriers and with sound-absorbing paving), insertion of wildlife underpasses and treatment plants of first rainwater.

The design characterizing aspects concern the landscape and environmental interventions (to mitigate the infrastructure insertion) and the important naturalistic engineering works