Project Highlights

Construction Launching Phases

Project Duration: January – July 2012

Contractor: Collegno

Designer: Ing. Silvan Pier

Builder: Castaldo SpA

Static Scheme: Girder — Simply Supported Twin-Beam

Length: 80 m

Span: 1

Deck: Double composite steel-concrete section with twin welded plate girders and transverse beams — width 12.5 m (9.7 m carriageway), height 3.60 m

Steel: Weathering steel with improved corrosion resistance (UNI EN 10025-5): S355J0W+N open rolled profiles for thickness ≤20 mm; S355J2W+N for welded plates with thickness >20 mm

Total Steel Weight: 292.5 t per deck

Restraining Device: Elastomeric isolator pads

Photos: Castaldo SpA, Renzo Miglio, Gianni Grigoli (Aero Club Torino)

The Ponte Sulla Dora Riparia is an 80-meter twin-deck steel bridge located in Collegno, near Turin, Italy. Inaugurated on July 6, 2012, the bridge represents a strategic infrastructure investment of €12.5 million, serving as a critical connection between Corso Marche in Turin and the SS24 in Collegno, alleviating traffic congestion in the historic center and the densely populated Oltredora district . The project included two separate steel decks, a 120m approach tunnel, and 1,900m of embankment road, with each deck utilizing 292.5 tonnes of weather-resistant steel (S355J0W+N and S355J2W+N) to ensure long-term durability and reduced maintenance .

Construction employed the longitudinal incremental launching method for erecting the twin steel decks, enabled by BIM modeling with Tekla Structures for precise fabrication and installation sequencing . My role involved technical direction, construction oversight, and quality assurance, working alongside Castaldo SpA to ensure the bridge's successful completion and integration into the regional transport network .

The following activities were carried out on site to ensure the safe and efficient execution of the bridge launching operation:

1. Preparation of the Assembly Area and Launching Skids

The assembly area was prepared and leveled to accommodate the steel deck segments and launching equipment. Launching skids were assembled on the shoulders, providing a stable and aligned platform for the incremental launching process. The skids were precisely positioned to ensure accurate alignment with the bridge axis and to support the weight of the deck during the launching sequence. This preparatory phase was critical for establishing the correct geometry and alignment for the entire operation.

2. Assembly of the Bridge Deck and Launching Nose on Concrete Blocks

The steel bridge deck was assembled on temporary concrete blocks positioned along the assembly area. These blocks provided a stable and level working platform, allowing for precise alignment and welding of the steel segments. Simultaneously, the launching nose — a lighter steel structure designed to guide the deck onto the opposite abutment — was assembled and rigidly connected to the front end of the deck. The launching nose was essential for reducing the cantilever bending moments during the launching phase and for facilitating the smooth engagement of the deck with the receiving rollers on the far abutment. The assembly of both the deck and the nose was executed with rigorous quality control, including welding inspections and dimensional verifications, to ensure structural integrity and geometric precision.

3. Removal of the First Support and Positioning of Trolleys and Roller Conveyors

The first temporary support was carefully removed to allow for the insertion of the launching trolley and roller conveyors beneath the deck. The remaining intermediate supports were systematically eliminated, transferring the load progressively onto the launching system. At this stage, the bridge deck was supported on one side by the launching trolleys and on the other side by roller conveyors positioned on the upstream shoulder. This configuration allowed the deck to move freely along the longitudinal axis while maintaining lateral stability and alignment. The roller conveyors were calibrated to accommodate the weight of the deck and to minimize friction during the subsequent launching operations. The removal of the intermediate supports was executed in a controlled sequence to avoid sudden load transfer or misalignment, with continuous monitoring of support reactions and deck displacements.

4. Incremental Launching Advancement

The advancement of the deck was achieved through the incremental launching method, a sophisticated technique that progressively moves the bridge deck forward using hydraulic jacks and sliding systems. The procedure involved the following key steps: (a) hydraulic jacks were used to push the deck forward by a predetermined stroke length, typically 1 to 2 meters per cycle; (b) after each advancement, the jacks were retracted, and the system was reset for the next cycle; (c) during the advancement, continuous monitoring was performed to ensure alignment, level, and structural behavior remained within acceptable tolerances; (d) roller conveyors and sliding bearings facilitated the movement, reducing friction and preventing damage to the steel deck. The incremental launching process was executed in repetitive cycles until the deck reached its final position on the opposite abutment. Throughout the advancement, the deck's structural response — including stresses, deflections, and alignment — was monitored in real time to ensure safe and controlled progression. The procedure was particularly challenging due to the weight of the deck and the length of the span, requiring precise coordination between the launching team, site engineers, and construction management.

5. Lowering of the Deck to Final Height

Upon completion of the launching advancement and positioning of the deck over the final supports, the bridge was lowered to its permanent elevation. This was achieved by systematically removing the roller conveyors and launching styli from beneath the deck and progressively lowering the deck onto the permanent bearings. The lowering operation was performed using synchronized hydraulic jacks and temporary supports, ensuring the deck was transferred to the permanent bearings without inducing additional stresses or misalignment. Final alignment checks were conducted to verify that the deck elevations, horizontal positioning, and bearing contact met the design specifications. The lowering phase concluded with the installation of permanent bearings, elastomeric pads, and connection details, fully transferring the load from the temporary launching system to the permanent structural supports. This final step was critical for the long-term structural integrity, ensuring the deck's final geometry and bearing conditions were consistent with the structural design assumptions and operational requirements. The entire process was executed with rigorous safety protocols, quality control measures, and continuous monitoring by the technical team, ensuring the successful completion of the bridge deck installation.

Ponte Sulla Dora Riparia — Collegno, Italy (2012)

Composite Bridge

New Steel Viaducts — SS 117 "Centrale Sicula"

Location: Mistretta – Nicosia (ME), Italy
Date: 2017
Client: ANAS SpA
Contractor: Fegotto Costruzioni srl
Builder: LMV srl (Viadotti Rogillo I e II)
Other: Valori S.c.a.r.l.
Superstructure Design: Ing. Giovanni Costa (Steel Project)
Substructure Design: Ingecom Strutture S.r.l.
General Design: Alisea S.r.l.
Works Direction: Ing. Fabrizio Tragna
C.S.E.: Geom. Nunzio Battaglia

This project involved the design and construction of four steel composite viaducts along the SS 117 "Centrale Sicula" in Sicily, as part of a broader infrastructure upgrade totaling €58 million. The works also included two artificial tunnels — Galleria Salice 1 (165m) and Galleria Salice 2 (125m).

The viaducts feature a continuous girder configuration with double T profiles in welded composite sheets, utilizing corrosion-resistant steel (UNI EN 10025-5) with grades S355J0W, S355J2W, and S355K2W selected based on plate thickness. The composite steel-concrete deck has a width of 12.75m and variable height up to 3.47m.

Viaducts Overview:

ViaductSpansLengthSteel QuantityViaduct Montagna6 spans, 66m307.3m900t deck + 80t pulvini + 200t predallesViaduct Rogillo I3 spans, 60m140m360t deck + 30t pulvini + 80t predallesViaduct Rogillo II5 spans, 56m255m770t deck + 60t pulvini + 200t predallesViaduct Salice6 spans, 61m330m1020t deck + 80t pulvini + 220t predalles

Total Steel Quantity: Approximately 4,000 tonnes across all four viaducts.

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