According to its advertising materials, the Suburban Rail Loop (SRL) will transform Melbourne. Announced in the lead-up to the 2018 Victorian state election, SRL was received with excitement by the electorate. However, recent media coverage of the SRL has confirmed that the project’s genesis lay far outside ‘textbook’ planning processes. Further, there has been limited examination of the improvements to public transport accessibility achieved by the SRL in comparison to other potential network investment options available within its substantial budget.

In providing a frequent and rapid circumferential addition to the radial rail network, the SRL, in part, conforms to best practice network planning principles. However, as a single line with broad station spacings, the SRL’s accessibility improvements may be limited to the immediate vicinity of the project. Further, as an entirely tunnelled alignment, civil construction costs are vastly inflated over alternative, albeit slower, surface transit investments. Simply, much more service, and thus accessibility, could be provided for a given budget through surface upgrade options. 

To test this assumption, we developed an ‘Alternative Network’ structure using a conservative but still significant $25 billion budget. Costs were benchmarked against recent Australian heavy and light rail investments, along with slightly lower per-kilometre rates for traffic signal and road space priority treatments required for priority bus operations. Using these figures, we developed a conceptual, 600+ kilometre Alternative Network to test for accessibility against SRL East. This network comprises a combination of partially-to-completely segregated rapid transit lines and bus lines with priority initiatives. We also include select extensions to tram and rail lines. To ensure ‘network effect’ principles were maximised, service frequencies were set at a 10-minute headway. We developed our model for the SRL East network using parameters available to the public in the project business case, including service span, frequency, and station locations. In each model, existing service provision for remaining transit services was otherwise left as is. 

Our findings indicate that the Alternative Network offers substantially improved metropolitan wide accessibility outcomes compared to the SRL East. With a lower capital budget, accessibility improvements accrue across the entire metropolitan area, rather than to a narrow corridor in the eastern suburbs.