Since 1959, the Berger Group has maintained the largest transportation consultancy in Africa working in 52 nations throughout the continent.

Reconnecting MOZAMBIQUE

Near the town Xai-Xai, in fertile Gaza province, the 190-meter, cable-supported Xai Xai Bridge opened to traffic in 1964, serving the Maputo-Beira corridor, the main north-south artery in Mozambique. The structure, crossing the Limpopo River 200 kilometers north of Maputo on National Road 1, was built with prestressed concrete and composite steel girders, a reinforced concrete deck, hinged pylons and reinforced concrete abutments. In 1989, however, a cable anchorage on the Xai-Xai side failed sending two deck spans, 72 meters in length, into the river along with the pylon on the Xai-Xai side. The Berger Group was selected by the Ministry of Public Works to provide construction supervision services, including preparation of tendered documents, assistance in bid evaluations and negotiations for the $5 million, OPEC-funded rehabilitation project, which included replacement of the pylon on the Xai-Xai side and three central spans totaling 110 meters. Additionally, new suspension cables were installed and new anchorage blocks fabricated. The effort was completed in 24 months, on budget, despite major logistical and security problems.

Adapting Designs in GUINEA

Nearly 25 years after the Berger Group first assisted in planning Guinea's highway modernization, we continue to help the government implement its ambitious program. In early 1999, the Berger Group was commissioned by the National Directorate of Rural Engineering, under a French Development Aid program, to prepare designs and provide construction supervision for the construction of eight bridges in Guinea's rugged western region. Given the region's isolation, low traffic volumes, annual rainfall of 3,000 millimeters and limited availability of local materials and skilled labor, the Team faced a challenging task in designing innovative, low-cost structures.

Of the eight bridges, two are reinforced concrete and six are steel, which were chosen when foundation soils were not sufficient to support heavier structures. The selected designs vary in length from 30 to 135 meters with reinforced concrete abutments founded on shallow footings or drilled piers. To reduce costs, two existing steel structures were cleaned and rehabilitated for reuse and low-cost steel elements were shipped from France for on-site assembly.

For the Ministry of Transport and Public Works, Berger/Brokonsult designed two reinforced, two-lane concrete bridges over the Bafing River between Mamou and Dabola. Because soils at the site of Bafing I were unsuitable for heavy structures and low-cost solutions were mandated, the Team selected a 30-meter, single-span, steel Mabey Johnson-type structure. The soil conditions were better suited for heavy structures at the Bafing II site, and a 105-meter, nine-span reinforced concrete structure was constructed. Both structures rest on reinforced concrete abutments. The Japanese aid agency, OECF, funded the two bridges under the $105 million upgrading of the 390-kilometer Mamou-Kankan road, for which the Berger Group also provided construction supervision services. Under the same program, the Berger Group was selected to supervise construction for the $8 million, 385-meter Niger and 25-meter Manie river bridges and their access ramps along the 83-kilometer Kouroussa-Kankan link. In order to determine the necessary construction parameters, the Berger Team carefully analyzed riverbank stability, river bottom slope, fill materials and river currents. The studies revealed that huge pools of water would form along the access ramps after rain. To reduce the potential for flooding, the Team altered the original design raising the access ramps and bridges by 30 centimeters. The two prestressed concrete structures will rest on reinforced concrete abutments and drilled piers. Both the Niger, with 11 prestressed, dual-beam, concrete spans, and the Manie, a dual-beam, single-span structure, will replace current ferry operations.

The Berger Group, in late 1998, was selected to supervise construction of the 270-meter, six-span Fatala River Bridge. The site, at the narrowest point in the river, was selected by Berger engineers in 1976 under our master plan developed at the onset of Guinea's highway modernization program.