Fatala and Tibola bridges

Technical-economic feasibility, final design and DAO preparation (phase 1) and works control Mission (phase 2) for the construction of the bridges over the Fatala and Tibola rivers and access roads (19 km)

Country

Guinea Conakry

Name of Client

Ministère des Travaux Publics et Transports-Direction Nationale des Investissements Routiers

Financing sources

EDF

Association

Louis Berger – France (Leader) – Bonifica – Italy (member)

Duration

12/1998 - 06/2004

Project Description

Technical studies for the construction of 2 bridges over the Fatala and Tibola rivers and 19 km of roads. The design includes bathimetric study, hydraulic study, geological study. It presents some execution difficulties for high tide variations (2,5-3 m), water covering (about 40 m), strong currents (3/4 m/sec) and for the strong seismicity of the zone.
AIC Progetti carried out the tides and currents study through the use of particular survey equipment. AIC has also carried out the geotechnical study of foundation soils through deep bore holes carried out in water and seismic surveys. The underlying rock has been consolidated by a seam realized by vertical or inclined micro-piers, reinforced and injected with cement mortar. The deck of the Fatala bridge has been carried out through the technique of cantilevered advancement with successive poured-on-site segments starting from piers. The cross section is made of 12-m wide precast concrete segmental box girder.
- Bridge over the Tibola L = 106 m – prestressed concrete beam span 35 m– foundations on micropiles (water speed 2 m/sec – tide height 2.50 m)
- Bridge over the Fatala : continuous beam prestressed concrete bridge total length L = 325 m (central span of 160 m and two side spans of 82.50 m – foundations on micropiles ).
The design has been divided into 2 phases: the first one concerns the design whereas the second concerns the Works supervision and control.

Services Description

Preliminary and final design, preparation of tender documents; works supervision and control. AIC Progetti carried out the final design.
Bathymetric and currents study, geotechnical study, hydraulic study, topographic study, bridge and foundation computation, carriageway dimensioning.