A report by the Victorian Audit Office on the operation of market proposals, presented in November 2019, criticized the West Gate Tunnel project and concluded that the government had approved the new tunnel without sufficient evidence that Transurban`s market proposal showed value for money and “unique qualities”. The report stated that Officials from the Department of Finance had not warned the government that the extension of the CityLink toll “could create an involuntary monopoly advantage for Transurban.” She said finance officials had not really considered a range of project options or other options – in addition to extending the Transurban toll to CityLink – to pay for the new route. “The business was not comprehensive enough, undermining one of its main objectives – to give decision makers the confidence that they choose the right investment option,” the audit said. Transportation planner William McDougall announced in 2017, before a Senate committee hearing on toll road operations, that he had been tasked in 2015 by the Victorian government with supporting an outside peer reviewer to model the tunnel project and conducting a peer review of its cost-benefit analysis. He was convinced that both traffic modeling and cost-benefit analysis were flawed and would not stand up to scrutiny. After expressing his concerns with Treasurer Tim Pallas, he was removed from the project`s work. His submission to the Senate committee stated that transportation modelling had been “hidden” and that the cost-benefit analysis overstated the benefits of the project. He wrote that the work for the project was “focused on developing bulls and optimistic and financial forecasts … my direct experience as auditor confirmed my long-standing suspicions about a significant “optimism bias” in the evaluation process.   Contractors CPB Contractors and John Holland created about 450 jobs ahead of the legal challenge, with more than 300 job cuts following threats from contractors. Tunnel ventilation structures have generally been considered environmentally friendly. Air quality was expected to improve near roads that would be subject to permanent HGV curfews, but increased traffic on some roads, including Millers Road and Geelong Road, would have a negative impact on air quality.  [Note 1] The SEA`s social impact assessment found that significant increases in traffic for both millers and Williamstown roads were problematic for residents.
Residents of Millers Road would experience reduced safety and amenities and greater difficulties in accessing services and facilities south of the West Gate Freeway, while on Williamstown Road they would adversely affect connectivity and travel times and affect the likelihood of cyclists and pedestrians using and crossing the road.