More Projects

Mt Edgecombe Interchange Upgrade

Our Role

SMEC provided Consulting Engineering services throughout the decade-long Mount Edgecombe Interchange Upgrade project, which was launched in 2009 and completed in 2019. Major design constraints were overcome using a four-level, free-flow interchange configuration.

Project Overview

Currently considered to be the largest interchange project in South Africa, the Mount Edgecombe Interchange Upgrade involved shifting an existing diamond interchange layout to a free flow, four level interchange configuration.

The upgrade includes nine new bridge structures, of which the main feature is two free flow ramp viaducts that are 443 m and 947 m long and 18m and 26m high, respectively. The viaduct span lengths vary with the longest spanning up to 65m.

The viaducts were constructed using the Incremental Launch Method to accommodate traffic and elevation constraints.


The Mount Edgecombe Interchange boasts one of the longest incrementally launched bridges in the southern hemisphere at 947 m long. Some of the major design considerations included physical space constraints due to current and future developments, road reserve boundaries, traffic congestion, future traffic demands, proximity of the Gateway Theatre of Shopping off-ramp from the M41, existing storm water attenuation areas, and accommodation of future development access and future capacity.

The resulting four-level, free-flow interchange configuration provides for full-width free-flow directional ramps in all directions whilst keeping the geographical footprint of the interchange as small as possible and largely within the constraints of the road reserve.

SMEC South Africa won the Technical Excellence category in the 2018 South Africa Institute of Civil Engineering (SAICE) Durban Branch Awards for the Mt Edgecombe Interchange Upgrade as well as the 2019 Consulting Engineers South Africa (CESA) Roads and Bridges category.

South Africa
Technical Area:
South African National Roads Agency SOC Ltd.

Learn More

To learn more about our Transport capabilities please fill out the form below and one of our team will be in touch.