Construction World January 2018

THIS PROJECT WAS ENTERED IN BEST PROJECTS 2017

ROADS & BRIDGES

PROVINCIAL MAIN ROAD 577

I t is to their credit that the KwaZulu-Natal Department of Transport and the eThekwini Transport Authority as well as the designers and contractors not only met the challenge head on, but came through the experience proud of their achievement, truly ‘Enhancing Society Together’. Construction innovation technology The intricacy of the design indicates the level of detailed engineering judgement, innovation required and time spent integrating the geometric requirements of an arterial road into the most complex and challenging terrain. After having completed the design of a 4-lane split-level road, the decision by the KwaZulu-Natal Department of Transport and eThekwini Transport Authority to convert this to a 6-lane option (4-lane:2-lane configuration) with the different geometric requirements and pavement design inherent in a Bus Rapid Transit (BRT) project placed immense pressure on the design team. Unusual construction methods The steep terrain required well planned methods of excavating the cut. The stipulated method of operation permitted the contractor to work in 7 m depths in the cut face. A drilling depth of 7 m was permitted for blasting; 3,5 m of the blasted material was removed by conventional earthmoving methods, the exposed 3,5 m of exposed cut face was inspected and the position of the rock bolts planned and installed before the remaining 3,5 m of blasted material was removed and the exposed face inspected and the position of the rock bolts planned and installed. The next 7 m depth would then Main Road 577 was developed to provide critical access for local residents to jobs and economic activity in the New Germany and Pinetown areas of Durban. The final result displays the socio-economic impact of how the project team worked with the community to achieve the goal of providing them access to socio- economic opportunities.

commence – this method was followed for the entire 7 m of cut slope that was removed. Corporate Social Investment In consultation with the employer and the project liaison committee (made up of representation from the employer, local ward councillors, engineer and contractors), it was determined that the labour force would be drawn predominantly from the local community within the four surrounding municipal wards. Recruitment of labour was carried out through the local ward councillors and their CLOs. A training centre was established which provided construction related skills training to the local labour and community who were then in a position to be employed by the contractors engaged in the construction of this and other phases of P577. The CPG target was specified at 10% of the contract value. CPG value of 42% of the contract value was achieved. A total of 637 local community persons were employed and a total of 10 local sub- contractors were appointed during the duration of the project. Design innovation The KwaDabeka Valley was the most challenging portion of the project as the road had to climb at average grade of 6,2% and as steep as 9,7% in places. The geotechnical challenges faced by the design and construction teams tested their ingenuity to the limit as solutions had to be found to ensure the stability of the rock face. Conditions varied continuously and it was not possible to apply a single solution to rock retention. The surface of the steep natural slope is underlain by soils and rocks of the Marianhill Formation of the Natal Group Sandstones. Outcrops of sandstone occur as sub horizontal ridges across hillsides. Cutting Design In order to accommodate the alignment of the carriageways within the steep sided valley, a rock slope cut at 63 degrees to the horizontal was selected to optimise the geometry of the road and to minimise risk. Rockfall interception measures were installed on insitu ground at the crests of the main cuttings utilising a gabion basket structure

A Northern view from the start of the project.

Gabion work getting the stone up the slope.

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CONSTRUCTION WORLD JANUARY 2018