THE South African National Roads Agency Limited (Sanral) paid over R10bn more than it should have for the Gauteng Freeway Improvement Project (GFIP), with a price tag of R17.9bn.

This is according to the Organisation Undoing Tax Abuse (Outa), formally know as the Opposition to Urban Tolling Alliance.

The organisation on Sunday released a report comparing the cost of the GFIP project to the cost of 11 case studies on the continent and abroad in developing and developed nations.

The investigation showed that compared to all cases, on average Sanral overpaid by 321% per kilometre of 185km of road constructed and upgraded under the GFIP project, than was paid for roads in the eleven case studies.

Outa said that if the fair price of R7bn had been paid for the GFIP project instead of the R17.9bn that was paid, repayment costs for loans taken to fund the project would have been less than R1bn at an "achievable" interest rate of 10%.

With loan repayments of less than R1bn, this would mean that servicing the total debt of the road upgrade would have cost less than the e-toll collection costs, rendering the scheme "highly irrational and unacceptable".