Roads Minister Duncan Gay said on Friday that the government was reviewing the toll on the tunnel, but he did not disclose at the time that Transurban had lodged an unsolicited proposal. The fact that Australia's largest toll road company has gone to considerable lengths to lodge a formal offer raises the likelihood of a change to the tunnel's tolling regime, or the way it operates as part of Transurban's extensive Sydney motorway network. "For them to voluntarily reduce the toll, [it] must include something else," Martin Currie analyst Andrew Chambers said. "Reducing the toll would tend to result in lower revenue." Apart from offering motorists who drive between the eastern suburbs and the inner west a means of avoiding congestion in the CBD, the tunnel links to the Eastern Distributor, which is at growing risk of traffic jams due to congestion in the central city from the construction of the $2.1 billion light rail project. Transurban's latest unsolicited offer – the details of which remain bound by commercial-in-confidence rules – is under consideration by various government departments, including Transport for NSW.

The Baird government is expected to reveal details of the proposal, and its response, before Christmas. The proposal was received several months before the closure on Friday of the first section of George Street in the CBD to allow for construction of light rail lines connecting Circular Quay to Randwick and Kensington in the city's east. Transport chiefs and government ministers have been warning for months that the construction of the tram lines over the next three years will strain the city's transport network. It has led the NRMA to call for a lowering of the Cross City Tunnel's tolls during the construction period. But relatively benign traffic conditions in the central city following the closure of George Street to traffic on Friday may make any changes to the Cross City Tunnel less compelling for the government, which has already committed $2.1 billion to the light rail project. Analysts have also questioned whether increased congestion in the CBD from the light rail project will funnel large numbers of motorists into the Cross City Tunnel. However, a lowering of the toll is likely to be a significant incentive for motorists.

The proposal from Transurban comes just months after the state government decided to raise tolls on new Sydney motorways faster than the rate of inflation once sections of the Westconnex motorway are completed over the next decade. Built for about $1 billion, the Cross City Tunnel has attracted only a fraction of the predicted traffic since it was opened 10 years ago. While average daily trips through the tunnel rose almost 4 per cent in the three months to September, it still had the weakest growth of all of Transurban's Sydney toll roads. Greens transport spokeswoman Mehreen Faruqi said taxpayers should not be asked to compensate Transurban for lowering the tunnel's toll. "If the Government should be subsidising anything, it's public transport," she said. Transurban owns or holds stakes in most of Sydney's toll roads, including the Westlink M7, the Hills M2, the M5 South West and the Lane Cove Tunnel. The company has made an habit of lodging unsolicited proposals with state governments as a way to push through projects and increase its stranglehold on tollroad networks in Sydney, Brisbane and Melbourne.