Indian contractor sets new slipform paving records

• Accredited training was required for all levels of work. Once this ministerial determination was in place, it was possible to modify the NPWP to morph into the present-day EPWP.

In 2004, the following was recommended for the training of ‘hands-on’ site supervisors.

As part of the full NQF 4 Construction Supervisor qualification, trainees in South Africa must complete the 120 notional hours required for Unit 15168 (Implement labour-intensive construction systems and techniques) and the 80 notional hours required for one of the remaining three unitstandards, namely: • 15165: Use LIC methods to construct and maintain roads and stormwater drainage • 15159: Use LIC methods to construct and maintain water and sanitation systems • 15166: Use LIC methods to construct and maintain structures. A crucial principle of LIC is the task-based payment stipulation – i.e. payment is made on completion of a set ‘task’. From April 2020, the government minimum in the civil construction sector is about R37/hour. At these rates, however, even on a task-based payment, no one can compete cost-competitively with fuelbased equipment.

Conclusions

The execution of LIC cannot create jobs in the absence of engineering. It is innovative engineering that creates the perfect match between community-based labour and construction technology.

LIC programmes only work if they are led by ‘hands-on’ and formally trained site supervisors who can effectively work within a task-based system. If we can effectively mentor and grow these infrastructure leaders, then the prospects are very promising for community-based employment.

A positive step in this direction is now emerging with the proposed establishment of a labour-intensive training college housed within the Department of Public Works and Infrastructure’s EPWP. A major focus of this current endeavour is to get formal approval for the three NQF 4 Construction Processes Site Supervisor courses. *Robert McCutcheon is a professor emeritus of the School of Civil and Environmental Engineering at the University of the Witwatersrand.

Due to its size, this megaproject has been divided into more than 50 individual subprojects awarded by the National Highways Authority of India. Initially, the roadway will be widened to eight lanes, with four lanes in each direction. Looking ahead to the future, however, sufficient space has been set aside in the middle of the road to allow for four additional lanes.

At temperatures around 28°C, it being winter in this region, the record attempt started on 1 February 2021 at 08:00. Using a modified Wirtgen SP 1600, Patel Infrastructure succeeded in completing a four-lane motorway, including a hard shoulder, over a distance of 2.56 km (1.28 km in both directions) within 24 hours.

Four world records

A total of four world records were entered into the India Book of Records and the Golden Book of World Records in connection with Patel Infrastructure’s project for: • Largest quantity of pavement quality concrete (PQC) paved in 24 hours – 14 613.30 m³ • Largest volume of PQC produced in 24 hours – 14 370 m³ • Longest continuous section with a width of 18.75 m paved with PQC in 24 hours – 1 280 m • Largest area of a motorway paved with PQC in 24 hours – 48 711 m². The standard paving width configuration for the SP 1600 is up to 16 m, so, in order to meet Patel Infrastructure’s requirements, Wirtgen’s R&D Department developed a customised solution. This involved additional extension elements for each component, including the extremely complex dowel bar inserter. The machine also had to be able to compensate for the enormous amount of additional weight and still be capable of high-precision levelling.

Patel Infrastructure’s Wirtgen TCM 180 texture curing machine was also adapted to match the 18.75 m working width to apply a dispersion to the concrete surface behind the slipform paver as protection against evaporation.

To ensure that the customised machine always ran smoothly, the construction project was supported by four Wirtgen technicians. Every hour, a total of 45 transport vehicles delivered concrete to the construction site to provide the slipform paver with sufficient material.

To be able to process this enormous quantity of concrete in such a short time, the paving process had to be carried out at an average speed of 1.8 m/min. Approximately 30 000 dowel bars and tie bars were inserted using the built-in automatic dowel bar inserter and the central tie bar inserters. This provides the structure with the necessary stability, ensuring that the slabs are bonded together properly to withstand traffic loads for many years to come.

Setting a new benchmark in its class, a modified Wirtgen SP 1600 slipform paver helped Indian contractor Patel Infrastructure set new records for performance on a section of the 1 350 km Delhi-VadodaraMumbai Expressway. The route is currently undergoing a major upgrade, scheduled for completion in January 2023.