Johannesburg - Toll tariffs will not increase to make up for the cost of repairs to a section of the N1 highway, the transport department said on Thursday."Any defects on the Gauteng Freeway Improvement Project toll network will not result in an increase in toll tariffs... An investigation is underway in this case and the responsible party will be made to pay for the repairs," Transport Minister Sibusiso Ndebele said."We want to assure South Africans that government will not accept any sub-standard construction on any of our roads."This followed reports of warping of the surface of the highway between the Beyers Naude and Malibongwe off-ramps.Transport spokesperson Logan Maistry said the SA National Roads Agency Limited identified the warping in October last year."A task team of pavement and material experts have been attending to the matter. The contractual arrangements make provision for a defects liability period, and any defects of whatever nature that manifest are repaired by the contractor."