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FAST-TRACK ROADS RELOCATION FOR LEEUWPAN COAL MINE

Bypass closure lighting to make it more visable and safe for road usersJG Afrika was appointed by Exxaro Resources to provide engineering design and construction supervision services for the relocation of two roads to enable it to access new coal reserves at Leeuwpan Mine in Mpumalanga.

The 6 km section of the provincial road R50 and 6 km private road that services the nearby silica and quartzite mine, Thaba Chueu Mine, were redirected in only eight-and-a-half months.

This was at least two months ahead of the fast-track construction schedule, despite rainy weather and other circumstances that led to unforeseen delays.

A decision was taken to incorporate precast-concrete base slabs for the 11 000 m of prefabricated culverts that were installed along the routes. To further accelerate the works programme, the contractor sourced quality crushed aggregate and rock-fill directly from Thaba Chueu Mine.

A novel solution was devised to stabilise the bases for the 14 large 2,4 m x three metre storm water structures that were installed in the marshy terrain with rock grid, bidim, rock fill, 19mm and 6.4mm aggregate.

Impact compaction rollers were used on as much as 80% of the road distances to accelerate the treatment of large areas located in commercial maize farmlandsImpact compaction rollers were used on as much as 80% of the road distances to accelerate the treatment of large areas located in commercial maize farmlands. Impact rolling has the added benefit of obtaining much better levels of compaction at depth.

The private road features a 16 mm micro surfacing, Ralumac. Ralumac is a rapid-setting cationic modified rubber bitumen slurry AC-E1 and known industry-wide surfacing alternative that facilitates fast construction. Resulting surfacing is highly durable and resistant to permanent deformation, like rutting and shoving.

The haul road comprises a 150 mm thick base course, 200 mm sub-base layer and two selected layers, and the contractor deployed a state-of-the-art road recycler for stabilisation to provide a consistently homogenous mix. Cement bags were unpacked and squeegeed by hand to assist in creating jobs via labour-intensive construction practices.

The bypasses along the provincial corridor were built to high pavement standards and illuminated with solar studs and mobile high mast lights, while extensive signage was installed on both sides of the road to alert traffic.