Part of the first phase in the expansion of the A-4 Motorway in Portugal includes both the construction of a new tube 367m in length and the renovation of existing tubes. The new tube, located just north of the original tunnel, will have four separate lanes for traffic travelling from Amarante to Porto; the original tubes will provide passage for traffic in the opposite direction. The project is designed to drastically improve travel conditions for traffic going in and out of the city of Porto.
One of the complexities posed by the project was its location in an urban centre with significant geotechnical risk, characterised by thin soil cover and areas of extremely weathered granite.
ULMA’s technical team developed three separate structures in partnership with the client, in order to make work as efficient as possible. First, a BRIO-MK scaffolding carriage was used to waterproof the entire tunnel. A similar carriage was then used to install the rebar. In both cases, ULMA’s most versatile systems were combined to create carriages adjusted and optimised to meet the demands of the project without any need for oversizing. Afterward, the MK formwork carriage was used to pour the tunnel structure itself.
Using a single MK formwork carriage 12.1m long, 10m tall, and 19.2m wide, the tunnel was entirely completed in three months, including assembly and disassembly.