Montrose Interchange

Gaining

an

edge

through

embedded

VR

technology

Virtual reality (VR) technology allows engineers and clients to view and manipulate their projects in a 3D environment, where any flaws or potential risks can be highlighted and mitigated before implementation, potentially saving a great deal of time and money.

The Challenge

The Montrose Interchange sits on the only east-west route between South Africa and Mozambique, eventually linking Botswana to the west. This transport system is critical to the economies of all three countries.

The interchange occupies a narrow space between the Crocodile and Elands Rivers, with constrained topography and rough terrain presenting challenges to design standards. The original road design, initially constructed in the 1970s had become inadequate for modern traffic volumes.

To achieve our client’s vision of a new grade-separated interchange that would facilitate free-flow for all traffic movements, the design had to be cost effective yet of the highest standards achievable. Bringing the entire project into the 3D space, and especially into VR, enabled everyone involved to experience the completed project before construction even commenced.

Location

South Africa

Client

Trans African Concessions (Pty) Ltd. (TRAC)

Year

January 2019 – 2023

Expertise

Digital Engineering Civil and Structural Engineering Project Management Survey

Most projects of this nature are undertaken with constrained budgets that do not make provision for detailed modelling. Leveraging our in-house technological capacity we were able to bring the entire project into the 3D space which enabled stakeholders to experience the completed project before construction even commenced."

— Warren McLachlan, Roads and Highways Engineer and Technical Specialist

Solution

SMEC was appointed as lead consulting engineer, responsible for delivering a comprehensive solution that included the realignment and upgrade of 600 meters of the existing road, construction of four new interchange ramps, and the widening of the Crocodile River Bridge from two lanes to five.

A significant aspect of the project was the innovative use of digital tools and methodologies. SMEC created a 3D digital twin of the site using drone-acquired photos, significantly reducing the project timeline and initial survey costs. This digital approach also facilitated the development of a Building Information Modelling (BIM) environment, ensuring meticulous detail in every aspect of the interchange design and laying the groundwork for future BIM compliance.

“Most projects of this nature are undertaken with constrained budgets that do not make provision for visualisations or detailed modelling. This meant we had to work smarter than ever, leveraging our in-house technological capacity and specialist expertise to provide innovative solutions in a highly competitive market.” Warren McLachlan, Technical Specialist

The Montrose Interchange, uniquely situated at the confluence of two steep valleys, presented substantial topographical and infrastructural challenges. The existing Crocodile River Bridge, with its complex geometry, posed a significant design challenge. SMEC addressed these by incorporating two new deck-stiffened arch bridges, realigning the N4-6Y to eliminate a hazardous blind curve, and widening the existing Crocodile River Bridge. The innovative design minimised environmental impact, preserved natural features, and enhanced road safety through improved visibility and traffic flow. The arch bridges were designed to leverage the natural strength of the hard rock cuttings, eliminating the need for conventional support structures and integrating seamlessly with the surrounding landscape.

The aesthetic considerations were paramount, with the design team intentionally seeking structural options that complemented the natural environment. The arch bridges feature visually slender elements that enhance their transparency, maintaining the natural beauty of the site. The arches have a very flat span-to-rise ratio, creating a shallow, elegant form that blends seamlessly with the landscape. Aesthetic lighting was incorporated into the bridge structure to highlight the architectural elements and improve night-time visibility and safety.

Impact

The Montrose Interchange Upgrade had a positive social impact, creating over 350 jobs for local laborers and engaging more than 20 local subcontractors. The project supported the development of small and medium enterprises (SMMEs) and provided extensive training opportunities, contributing to the economic upliftment of the Mbombela communities.

“SANRAL’s partnership with TRAC, and provincial and local government, delivered a new, state-of-the-art road infrastructure which meets the best engineering and construction standards in the world. This project shows us that South Africa has the capability to build freeway interchanges that can compare to any similar projects in countries with advanced and highly developed economies.» Minister Sindisiwe Chikunga at the Opening of Montrose Interchange

Throughout the project, SMEC maintained rigorous project management, ensuring adherence to budget and timelines despite the complex and challenging nature of the work. Their efforts culminated in the successful completion of the interchange in September 2023, which has since facilitated seamless traffic flow, enhanced safety, and boosted economic activity in the region.

Project stats

Realignment and upgrade of 600m of the existing N4-6y to facilitate the new ramp positions.
1800m of new directional ramps to facilitate free-flow movements in all directions.
Widening of the existing 160m-long Crocodile River bridge from two lanes to five.
Two new deck-stiffened arch bridges, anchored into the natural rock, spanning across the N4.
11 new energy-efficient high-mast lights to illuminate the interchange at night.
100% reduction in stopped delay for vehicles.