Tolls on one of Macquarie Infrastructure Group's key motorways will rise almost 8 per cent next month - a move that is expected to add momentum to plans to shift the company's best assets into a separate listed fund, where they will be shielded from debt and recession.

Peak-hour tolls on the 407 Express Toll Route in Toronto, in which MIG has a 30 per cent stake, will rise to C21.35¢ a kilometre from C19.85¢. About 320,000 vehicles use the highway a day, making it the company's most heavily used road.