Civil Engineering November 2022 | Vol 30 No 10

N aidu Consulting was appointed by the South African National Roads Agency (SANRAL) to investigate the cause and location of accidents on National Route 2 Section 27 (N2/27). The section of N2/27 under investigation starts from the Umhlali River Bridge at km 15.37 and ends after the Umvoti River Bridge at km 27.14. Further to the investigation, an assess- ment of the road geometry in accordance with SANRAL’s Geometric Design Guidelines was required on the horizontal curves north of the Umhlali and the Umvoti River Bridges, which were identified by SANRAL as being hazardous locations. A Detailed Assessment and Stage 1 Road Safety Audit were carried out as part of the investigation to determine the underlying causes behind the high accident rate along the N2/27. The following tasks were under- taken as part of the investigations: Q Q Analysis of existing accident records Q Q Analysis of current speed profiles Q Q Assessment of the horizontal curves north of the Umhlali and Umvoti River Bridges. OUTCOMES AND RECOMMENDATIONS The outcome of the investigation concluded that the horizontal curves north of the Umhlali and Umvoti River Bridges contributed to the high accident rates at these locations as they did not meet the minimum requirements to satisfy the 100 km/h (sign posted speed) and 120 km/h (85 th percentile) operating speed. The high accident rates were also attributed to the sudden reduction of the speed limit from 120 km/h to 100 km/h. Based on the findings, and in consulta- tion with SANRAL, it was agreed that the way forward would be to realign the horizontal curves north of the Umhlali and Umvoti River Bridges to meet the minimum requirements to accommodate the 85 th percentile operating speed of 120 km/h. This would serve to significantly reduce the likelihood of accidents as the 85 th percentile operating speed would be satisfied. PROJECT OVERVIEW The main scope of work for the construc- tion of the project was as follows: Q Q Realignment of the existing curves north of the Umhlali and Umvoti River Bridges Q Q Breaking up, removal and disposal of the redundant pavement layers, including the concrete layer and old asphalt pavement layers Q Q Removal of existing surfacing on bridge decks and replacement with a suitable asphalt surfacing Q Q Reconstruction of the pavement structure to match the existing jointed concrete pavement structure and lane configuration. While the scope of works for the con- struction of the road did not deviate from the conventional construction methods, the project was viewed as a great opportu- nity to showcase the innovations present in the industry by delivering the project construction and close-out phase through digitisation. The project is arguably the first road infrastructure project in South Africa to be implemented on the BIM 360 platform in 4D illustration. The software that was utilised to achieve the 4D model includes Civil 3D, Navisworks, Microsoft Projects and BIM 360. The implementation of this pilot BIM on the project was a first step towards understanding the benefits and efficiencies that can be expected from such a digitisation process and involved close collaboration between the client, consul- tant and contractor. The intention was for this to be a case study on the process of BIM implementa- tion and the applicability of its use during the project lifecycle, including mainte- nance and rehabilitation.  SANRAL SA I CE 2022 Nat i onal Awards Category: Techn i cal Excellence HIGHLY COMMENDED Technical Excellence category (Sponsored by SKI Civil and Structural Engineers) KEY PLAYERS Client: SANRAL Consultant: Naidu Consulting Contractor: Raubex KZN The Realignment of National Route 2 Section 27 from Umhlali River Bridge (km 15.37 to km 15.98) and from Umvoti River Bridge (km 26.4 to km 27.14) Civil Engineering November 2022 29 The Umvoti River Bridge before realignment The Umvoti River Bridge after realignment