Objective As Shenzhen transitions from an incremental, expansion-driven phase of urban development into a high-density, stock-oriented stage, the contradiction between the engineering nature of urban infrastructure and its public value has become increasingly acute. Facilities such as substations, water-pumping stations and other small-scale technical installations are typically operated as “functional black boxes”—single-purpose, physically enclosed, cognitively opaque and administratively monopolized—and therefore tend to generate pronounced Not-In-My-Back-Yard (NIMBY) effects in dense urban settings. This study addresses a central problem: under the dual constraints of strict operational safety and complex site conditions, how can institutionalized mechanisms guide such infrastructure away from being closed, single-function engineering objects and toward becoming open, shared and perceptible urban public domains rather than treating this as a purely technical or design question, the study reframes infrastructure renewal as a problem of urban governance and institutional design, aiming to identify the mechanisms through which engineering rationality and public spatial demands can be reconciled in a controllable, low-risk manner.

Methods The study adopts a combined historical review and case study approach. It first traces the spatio-temporal evolution of Shenzhen’s infrastructure, from the forward-looking, supply-oriented planning of the incremental era to the explicit emergence of NIMBY conflicts under high-density conditions, in order to situate the research problem within a concrete developmental trajectory. It then takes the institutional innovation of the “Small and Smart Design” (hereafter SSD) as the principal analytical entry point. Drawing on a body of first-hand process materials—including competition task briefs, organizational procedures, evaluation criteria, and records of expert interviews and post-competition “Cool Tea” review sessions—the study conducts a structural analysis of the institutional operating mechanisms rather than an evaluation of the aesthetic or technical merits of individual schemes. Competing design proposals are treated as "outcome-based manifestations" of institutional effects: the differences among multiple schemes serve as evidence for analyzing how institutional arrangements shape design decisions. Theoretically, the analysis is informed by Charles Lindblom’s incrementalism, which holds that under complex interest structures institutional change proceeds through small, risk-reducing adjustments, and by Patsy Healey’s collaborative planning theory, which locates the legitimacy of spatial governance in consensus built among multiple actors through cross-sectoral platforms.

Results The mechanism innovation of the two most recent infrastructure-themed editions of the SSD is concentrated in three interlinked stages: organization, translation, and implementation. At the organizational stage, a matrix-type cross-departmental structure was established with the “Center for Design” serving as the coordination interface, shifting the process of problem definition from the compartmentalised positions held by individual agencies toward a jointly constructed formulation among multiple parties. By adopting design quality rather than institutional seniority as the primary selection criterion, the competition actively expanded the range of participating design actors; across the two editions reviewed, emerging and cross-disciplinary teams accounted for 60% to 70% of all entrants, generating a markedly more diverse design ecology than would typically be found in conventional infrastructure procurement. At the translation stage, the mentor team and the organising body intervened in the drafting of the design brief at an early stage, making rigid engineering constraints—such as safe distances and structural load limits—explicitly legible to design participants. Through this process, the notion of a “creative safe zone” was advanced: engineering logic that would otherwise remain enclosed within the professional system was converted into information that designers could recognise, interpret, and act upon, substantially lowering the communication costs of cross-disciplinary collaboration. At the implementation stage, a phased procedure—spanning concept collection, scheme development, technical review, and evaluation refinement—allowed proposals to be revised continuously through successive rounds of technical feedback, distributing innovation risk across the process as a whole rather than concentrating it at a single decision point. This arrangement reduced the likelihood that design intent would be eroded or overridden during the engineering refinement phase. Guided by these mechanisms, the awarded proposals departed from the closed and inward-looking spatial conventions of conventional infrastructure and, without breaching engineering safety boundaries, explored the possibility of opening facility perimeters toward the surrounding urban fabric—replacing hard-edged, inaccessible enclosures with pocket parks, pedestrian linkages, and publicly usable edge conditions.

Conclusion The mechanism innovation of the competition runs through the wholeorganization−translation−implementation process, within which the "creative safe zone" constitutes the key link connecting the engineering-technical system and the spatial-design system. While holding firmly to the baseline of engineering safety, this mechanism effectively balances technical rigidity against the demand for spatial innovation, offering a workable path for public engagement in infrastructure renewal. The transition of infrastructure toward openness and sharing cannot be achieved by design means alone; it is the product of the coordinated interplay of organizational arrangements, technical translation, and design intervention. This study thus offers a reference in both mechanism and practice for high-density cities under stock-based development seeking to resolve the NIMBY (Not In My Backyard) dilemmaof infrastructure and to advance its transformation toward openness and sharing.