Civil Engineering Reference
In-Depth Information
single gantry would still be quite comfortable in placing the two decks per day. These
moulds and their attendant production lines would be more expensive than the simpler
moulds, and an economic comparison would need to compare the manpower and
capital requirements (
15.9.3
).
It would be possible to design a single wide deck to be built in this way. The deck
would weigh some 1,200 tons, a signifi cant step up from the 850 tons of the Poggio
Iberna Viaduct. However, from the studies carried out by Benaim on the prefabrication
and launching of decks weighing up to 1,500 tons, Figure 15.51, the weight is not a
barrier to feasibility. However, prefabrication of the deck will be slower; although the
author has not carried out any detailed assessment, a rate of six decks a month would
appear reasonable. The mould and its production line, the transporter and the placing
gantry will all be approximately twice the cost of the smaller units. Two moulds would
complete the deck in 16 months, marginally quicker than the three moulds for the
smaller deck. Intuitively, it does not appear likely that the wider deck will offer any
savings in construction technology, although as it could be carried by a single central
column, there may be savings in the cost of substructure, and project advantages in
adopting such a compact footprint.
