The concept of a’20-minute neighbourhood’ (20MN) is gaining momentum to promote sustainable, liveable communities. 20MNs can lead to increased physical activity and improved health outcomes, reduced dependence on cars, stronger social connections, increased economic vitality, and better access to services and amenities. This paper examines the benefits of the optimal placement of social infrastructure facilities such as schools within a 20MN from home which is defined as an area where residents have access to most of their daily needs within a 20-minute walk or bike ride. Our research shows that optimally placing such facilities can improve road network performance, save travel time, and reduce emissions. The authors tested the hypothesis in a simulated testbed of 37 traffic analysis zones in Greater Melbourne, using Aimsun microsimulation software. In the best-case scenario, savings were approximately A$12.3 million for the testbed. Moreover, the study found that maximum benefits occurred when 70% of the fleet was motorised and 30% was active transport. This indicates that simply shifting all modes to active transport would not bring maximum benefits. Therefore, policymakers and urban planners should consider a balanced approach to transportation in designing sustainable communities. Overall, the study suggests that the placement of social infrastructure facilities within a 20-minute walk is a valuable strategy for creating sustainable, liveable communities. The authors aspire that this study will add to the expanding knowledge base on this subject and assist in advancing the creation of sustainable and liveable communities.