Toowoomba is the major centre within the economically important Darling Downs and South West Regions. It is a key transport hub, and is formed at the confluence of three National Highways—the Warrego, the Gore and the New England. But it is also an important and growing city in its own right; after Canberra, it is the largest inland city in Australia.
It fills an important role as the connection between the urban areas of South East Queensland, and areas to the west, north and south, including Melbourne and Darwin. The region has a strong and diverse economy, sustained population growth and is well serviced with major road and rail links. The transport links include the Warrego, Gore and New England Highways, the existing South West and West Moreton rail lines and the proposed Inland Rail corridor. The transport network will play a critical role in ensuring that the region continues to grow.
The recently added Toowoomba Second Range Crossing (TSRC) provides additional capacity and redundancy (along with an improvement in grade and speed) for movements on the Warrego Highway, and for connections between the Warrego and the Gore Hwy. However north-south movements on the New England Highway are not well connected to the TSRC, limiting the potential use of the new road.
All of these factors indicate the need in the longer term for additional north-south capacity, more direct north-south routes, and improved connections between the New England Hwy and the Gore and Warrego Highways. The Toowoomba Western Arterial Corridor (TWAC) project has sought to explore the alternatives for these connections, with a view to protecting the corridor for the future needs of the Toowoomba network. The Charlton Bypass further extends the benefits of the TSRC, and better connects the TWAC with the Warrego Highway.
Stage 1 of the Charlton Bypass (CB) and the Toowoomba Western Arterials Corridor (TWAC) Option Analysis studies commenced in 2016 and was completed in 2018. TransPosition undertook the modelling for this work, and tested a wide range of network alternatives and staging options. In this stage of the project we worked closely with SMEC, who provided the transport and civil engineering advice for the feasibility of each corridor alternative. By combining our transport modelling with SMEC’s engineering design we were able to perform a full multi-criteria analysis, including an economic assessment of benefits to current and future users of the network.
From this work the preferred transport corridors were identified for both roads. For the TWAC, this involves a nominal 200m corridor and for the CB, a nominal 100m corridor.
Stage 2 modelling focused on corridor refinement and protection - it commenced in February and finished in June 2019. As part of the revised analysis the underlying model for Toowoomba was updated and refined.
Both stages of modelling involved innovative techniques for undertaking long-term planning for a future corridor. A full multi-modal corridor was considered, and transport modelling of active and public transport aspects of the corridor was included. This included the development of a 100-year development plan for Toowoomba, to allow the future corridor to be considered in the light of a much larger city. Potential technology changes were also considered, including the electrification of the vehicle fleet, and the introduction of connected and autonomous vehicles. Finally, the economic assessment was informed by innovative accessibility analysis, that allowed the multi-modal benefits and costs to be considered. This included an assessment of changes to people’s travel choices, not just savings in travel time.