Rehabilitation of Road N280/N281

The project involved the rehabilitation of Road N280/N281, between Tica, Buzi, and Nova Sofala in Sofala Province, Mozambique. Its aim was to ensure year-round connectivity between various cities in Mozambique. The entire area is prone to flooding, which heavily impacts the traffic flow. Aarvee Associates was appointed as the Detailed Design Consultant by the Authority, with Afcons serving as the Main Contractor. After the first phase of construction, it was discovered that the proposed structures were not adequate for the volume of water passing through during floods. As a result, we were scoped with the design of additional structures. These included 21 multicell box culvert bridges (with spans ranging from 1m to 3m), one minor bridge (with multiple 16m spans), and a retaining wall.

Designing culverts or minor bridges might appear straightforward. However, due to poor soil conditions consisting of 5 to 6m of soil fills, it wasn't possible to construct a box culvert on an open raft foundation. Hence, we designed special box culverts supported by piles. Normally, wing walls are separate when their length exceeds a certain cantilever limit. In this instance, however, a separate wing wall would have necessitated additional piles for stability. As a result, we designed an integral structure consisting of the main culvert and wing walls, which reduced the overall number of piles because the wing walls were stabilized by the main structure. Both the authorities and the contractor welcomed this approach, as it maintained the structure's robustness and durability while saving costs and time.