The South African National Roads Agency Limited (Sanral) on Tuesday responded to comments by Engineering News Online readers (see ‘Toll fee collection still months away, bulk of construction to wrap up end-June’) that sections of the newly-upgraded N1 were “sub-standard” in its surfacing.

Sanral noted that these soon-to-be-tolled sections, such as near the Rivonia off-ramp, would be repaired as soon as a suitable solution had been found.

Sanral senior project engineer Hennie Kotzé noted in a written response that the roads agency set and applied “very high standards to all work being executed. Very stringent quality control measures are being applied by both Sanral and the contractors executing the construction work.

“Through these processes the deformed asphalt surfacing has already been recorded when it first appeared towards the end of 2010.

“Since then Sanral, as well as the contractor, consulting engineers and product suppliers have been investigating the matter to determine the cause of the problem, as well as appropriate repair measures.

“Early indications are that the deformation is caused by moisture contained in the underlying pavement layers. The moisture migrate, probably due to high summer temperatures, to the interface between the underlying concrete pavement and the newly placed asphalt surfacing.

“Through traffic impact the water causes the asphalt to delaminate from the concrete, and deform.

“Sanral can assure motorists that we will maintain the high standards that we set and that these areas will be repaired as soon as the investigations have been completed and a suitable solution determined.”