Auditor general Terence Nombembe gave Sanral's books the thumbs-up recently.
Moody's downgraded the South African National Roads Agency Limited's (Sanral's) global long-term issuer rating from Baa2 to Baa3, and its national scale rating from A2.za to A3.za, it announced on Friday. It also placed the agency on review for a further possible downgrade.
The failure to implement e-tolling, has led to a "significant deterioration" of the company's cash flows needed to pay off the extensive debt it incurred to complete the Gauteng Freeway Improvement Project (GFIP), Moody's said.
Sanral took on R20-billion in debt to finance the improvement project, half of which is guaranteed by government.
It had however increased this debt stock to R36.2-billion as of March 2013, according to Moody's.
The ratings agency expected that debt levels could increase even further to around R39-billion by the end of the 2014 financial year.
Financial strain on Sanral
"E-tolling was initially expected to begin in June 2011 and its revenue was expected to absorb the company's mounting debt-service costs," Moody's said.
The resultant financial strain on Sanral, casts doubt "on the company's financial health in the medium term", the ratings agency said.
The launch of e-tolling faces further possible delays however.
Last week, the Mail & Guardian reported that the Transport Laws and Related Matters Amendment Bill – which must be passed into law before tolling can go ahead, has been delayed.