Montrose Interchange

    Pretoria, South Africa

Project Summary

    • Warren McLachlan

This project in the North of South Africa goes through Pretoria, through Mpumalanga province and mountainous terrain linking to the port city of Maputo, the capital of Mozambique. It is the only-east-west road between South Africa and Mozambique, eventually linking to Botswana to the west. The roadway is very important to the economies of these three countries as millions of people travel this route. The roadway was constructed in the 1970s and was not designed for the type of traffic volume the area is now experiencing. The project concerns a grade-separated interchange at the junction of the N4 and R538 roadway. The junction sits in a confined space between the Crocodile River Valley and the Yilantz River Valley, adjacent to the Montrose Waterfall to the south. Since the area was so constrained, it was difficult for SMEC to design an innovative solution that was different from its competitors.

Because the rough terrain prevented the team from exploring the site on foot, the team decided to take an aerial view of the site by capturing images using an unmanned aerial vehicle (UAV) and building a reality mesh of the site using ContextCapture. The 3D reality mesh gave the team greater context to site logistics and the alternatives that were available. OpenRoads Designer allowed the team to examine several alternatives and identify which one would be the most effective. Descartes was used to create scalable terrain models and LumenRT was used to visualize the project and present it to the stakeholders.

Using Bentley’s innovative design capabilities, SMEC was able to design a distinctive alternative for the grade-separated interchange that was so different from the designs of the competing firms. For example, the 3D model was able to identify the waterfall to the south, which the stakeholders did not realize would cause design constraints. The result of this finding was a huge savings in costs and design time.

ContextCapture provided an inexpensive high-level survey that cost about 5 percent of what traditional topographical surveys cost. The reality mesh identified issues that weren’t visible form the road including a waterfall, and what the underside of the bridge looked like. LumenRT created a visualization of the project that allowed the owner to see the exact configuration of the road including bends and curves. OpenRoads Designer helped solved the challenges with the difficult terrain that leads into a mountainous pass.

Project Playbook: ContextCapture, Descartes, LumenRT, OpenRoads™ Designer

  • South Africa’s highly competitive market means SMEC has to work more effectively using innovative solutions.
  • The road is bounded by Kruger National Park, which is home to the largest nature reserve in the Southern Hemisphere.
  • SMEC is headquartered in Australia and its South African arm began in 1947.
  • “Many of our clients do not have a background in civil engineering, therefore all road projects have to come out of very limited budgets. We have to work more smartly now than ever before, and Bentley helps us to do that.”

    Warren McLachlan Engineer, Roads and Highways, SMEC