SLIZZA III VIADUCT – ITALY
LOCATION: A/23 Udine-Tarvisio, Tarvisio UD, Italy
CONTRACTOR: Client: Autostrade per l’Italia SpA, Italy; Contractor: Divisione Cantieri Stradali Srl, Italy
PURPOSE OF THE WORK: Maintenance of steel box girder, side beams, abutments and pile
PRODUCTS: FlyDeck system with 25 cm aluminium beams, façade scaffolding, transport platform
HIGHLIGHTS: 7.776 sqm of working platform, load capacity of 150 kN/m2
Maintenance work in two separate and consecutive phases. The reinforced concrete deck and the supporting steel box girders are being refurbished while the bridge remains open to traffic heading to/from the border with Austria less than a 1km away.
FlyDeck structure on two levels on which four scaffolds were set up to work on 4 different heights.
The working platform at the lowest elevation has a width of 10 m, allows working on the lower part of the box girder and supports two scaffolds to work on the sloping sides of the box girder.
Additional frame scaffolding and trapdoors were also required on the two levels to secure access to the upper sections of the girder and the parapets. Structure-specific considerations included a 470m-radius of the deck alignment and a 5.6˚ cross-section incline that was compensated for by acting on the suspension chains. In fact, in some sections the platform is 1.7m away from the bottom of the girder and in others, in the middle, it is 1.9m, so the difference in elevation was addressed through the use of different chain lengths and adjustable chain elements.
Beams spacing: 1.80 m; chains every 3 m.
Steel anchor points consisting of rectangular sections of steel plate 10mm-thick and measuring 70mm by 70mm had to be welded onto the girder from an underbridge inspection unit at predetermined locations ahead of the decking install, and expansion plugs were used to anchor the platforms to the concrete parapets.
The steel anchor plates will remain on the bridge and serve as anchor points for future maintenance interventions.
