The Richmond Bridge Project, designed to ease congestion and improve travel times across the Hawkesbury River, is facing scrutiny after it was revealed that Transport for NSW (TfNSW) based its traffic forecasts on conservative housing development projections - about half the actual number expected in the next decade.

Underestimating the true scale of development could undermine the project’s claimed benefits, particularly travel time savings, external engineering experts told the Hawkesbury Post.

TfNSW relied on figures provided by Hawkesbury City Council, which included only three developments - Redbank, Vineyard, and Glossodia. However, Council is aware of significantly more housing proposals in the pipeline. In June last year, Council presented a document showing approximately 7,000 new homes were planned or undergoing approval. The recent rezoning of land for an extension of the Redbank development for 300 - 350 homes is not included in the analysis. Council did not respond to the Hawkesbury Post’s inquiries on the matter.

Traffic experts told the Hawkesbury Post that underestimating demand leads to underestimating travel time delays, while overestimating demand leads to inflated congestion projections.

“ The question of what future developments to include in an analysis is subjective. Usually, existing and approved developments are considered in short-run forecasts. The agency could also do scenarios of other possible developments,” one engineering expert said.

In this case, TfNSW did not model alternative development scenarios. It is unknown whether Hawkesbury Council provided any updated information to TfNSW when they became aware of future projections and new rezonings. As a result, the travel time projections in the report may not align with what residents are being led to expect. If the expected congestion relief is overstated, the bridge’s core purpose—reducing traffic delays—comes into question.

TfNSW’s model assumes that by 2029, Redbank will have 1,400 dwellings. Vineyard, currently with 50 homes, is expected to expand by 2,500 dwellings by 2035. Glossodia’s development, slated to start in 2024, was forecast to deliver 580 dwellings by 2032.

However, Council documents seen by the Hawkesbury Post show that the number of proposed and approved developments far exceeds the additional 4,480 homes accounted for in TfNSW’s projections. A surge in development west of the Hawkesbury River could bring more than 7,000 new dwellings in the coming years, excluding the 2,500 in Vineyard.

According to the document, developers have plans to construct housing estates spanning more than 1,500 acres in North Richmond, Glossodia, Freemans Reach, and Grose Wold - all of which would impact traffic on the new bridge.

Based on the limited developments supplied by Council, TfNSW’s modelling predicts reduced travel time. For example it forecasts reduced congestion in Richmond and North Richmond. The model claims that by 2029, westbound travel times during peak periods will drop by over one and a half minutes due to the new bypass. However, if the actual number of new developments proceeds as expected, these travel time savings are unlikely to materialise.

TfNSW told the Hawkesbury Post that it will assess the traffic impacts of additional developments through its normal planning process when referrals are received from Council.

“The traffic modelling includes the developments approved by Hawkesbury City Council at the time the modelling was undertaken. However, it assumes additional traffic growth in the wider network due to further housing development in the area. The proposed new Richmond Bridge would support future traffic growth beyond existing projections,” a TfNSW spokesperson said.

Critics argue that outdated modelling has created an overly optimistic picture of the project’s benefits. “The problem isn’t just the incorrect data,” the engineering expert said. “It’s that this data is shaping decisions about infrastructure spending and future planning that will affect the region for decades.”

Residents and councillors have raised concerns about the growing disconnect between promised infrastructure improvements and the realities on the ground. Hawkesbury Greens Councillor Danielle Wheeler has long criticised this approach. “There’s this really invidious idea that if you take that development, then you get the infrastructure to cope with the development,” Wheeler said. “When we know that that never happens, or if it does happen, it happens ten years later. And that’s too late for the people who are already living here. And it’s too late for people who are buying there as well. They have been sold a dummy.”