Abandoned railways allow an interpretation of urban borders by considering different scales of connection and separation. The former railway line in Aberdeen is used as a case study to explore how urban linear connections represent a defining linear space and may postulate a socio-spatial statement. The linearity of abandoned railways as an urban design issue is recognised as a characteristic of urban isolation and connection. The contemporary city is no longer a compact and homogeneous entity; its fragmentation and diversity make it prone to rapid transformation. The fragmentation represented by urban voids results from rapid urbanisation and new modes of transportation. Urban infrastructures, particularly railways, often necessitate redesign and are subject to relocation due to urban conditions. This relocation results in abandoned lines and, later, linear voids representing new micro-borders within a city. Focusing on an urban void and a residual form of a spatial condition that resulted from an abandoned railway line in Aberdeen, its potential role in connecting historically isolated and fragmented neighbourhoods are considered through three case studies of the successful transformation of abandoned railways. These are analysed to highlight the potential to develop a methodological approach to conscious urban reuse by addressing the challenges of planning and structuring specific design methods to create a network of connections and reinforce the importance of reactivating surrounding areas and places.