"Tolling can't be undone," said lawyer David Unterhalter, for the SA National Roads Agency Limited (Sanral).

"People drive on the upgraded roads everyday. We are going to fund it through tolls - it has been decided."

He said it was impossible to "go back to the drawing board" as Mike Maritz, for the Opposition to Urban Tolling Alliance (Outa), suggested on Monday while making his submissions.

Unterhalter said Gauteng motorists benefited from Sanral's Gauteng Freeway Improvement Project (GFIP) and therefore should pay for the upgrades.

He said that all the relevant civil society organisations representing Gauteng motorists knew about e-tolling and the user-pay principle since it started in 2008, but did nothing until the tariffs were announced in 2011.

"Civil society knew what was happening and informed their members. It is perfectly clear they knew what was at stake," said Unterhalter.

"[They] stood by for years as construction took place... No one was lulled into some sense of security. They could see the upgrades."

The Constitutional Court has overturned an interim order that e-tolling of Gauteng freeways be put on hold.

However, the High Court is still hearing a full review of e-tolling. It ordered on April 28 this had to be done before e-tolling could be introduced.

Unterhalter said Sanral undertook a huge risk to upgrade the highways.

"It causes the financial standing of my client to be scrutinised by potential investors," Unterhalter said.

"This is not just prejudice to Sanral but to South Africans as a whole, because they are beneficiaries of the upgrade."

Unterhalter said that the proposed difficulties with collecting the money was not a matter of concern, and said there were ways to collect the money, because the owner of the vehicle would be held liable.

The collection costs were not low but were manageable, he said.