Mbabane Bypass
Opened 8 May 2009
The Mbabane Bypass project was an exceptional project not only in size, but also for the intricacies involved in its design. One could hardly ask for a better advertisement for the technologies and applications of Reinforced Earth.
The Mbabane Bypass was finally opened for traffic on 8 May 2009. This section was considered the ‘missing link’ in the MR3 highway connecting the Ngwenya/Oshoek border post to Manzini.
The 11km section of highway through Mbabane is mountainous and lies in the middle of the rain-and-mist belt of Esetibeni, with a height differential of some 1 000m between the start and end with unstable founding conditions. The project presented many design challenges for RESA.
The project entailed the design and supply of materials for the construction of 5 600m² of bridge abutments, 6 700m² of retaining walls and 29 000m² of tiered fills all with HA and HAR steel reinforcing strips. Africon (now SMEC) undertook the detailed design of all bridges on the project.
The most notable of the designs, and most spectacular, are the 4 tiered fill structures which were designed as an alternative to incrementally launched bridges.The Esitibeni, Qabalambadada and Mangwaneni tiered fills with heights ranging up to 33m on centre-line, were originally designed as incrementally launched bridge structures. The massive tiered fills were all designed with 3m high and 2m wide tiers with associated geometric and setting out challenges. A full stability analysis was carried out in cooperation with the Consulting Engineers.
Project details:
Contractor: Wilson Bayly Holmes-Ovcon (WBHO)
Consulting Engineers: BCEOM Swaziland
Bridge / Structural Engineers: RESA /Africon