Urban underground works in dense cities face severe constraints: limited surface space, congested subsurface due to legacy utilities, heritage interfaces, and demanding stakeholder environments. Digital methods, particularly Building Information Modelling (BIM) and Geographic Information Systems (GIS), are crucial to manage this complexity, improve coordination, and support evidence-based decisions across planning, design, and construction. Lisbon Drainage Master Plan (PGDL) addresses recurrent flood risk intensified by climate change through a major set of underground infrastructures, including two 5.5 m internal diameter TBM tunnels in an urban environment (~6 km total), complementary shafts and surface structures in the historic centre, and interfaces with archaeological and existing assets. Digital construction was considered essential to face these challenges. From tender stage, PGDL defined BIM Exchange Information Requirements (EIR) and a post-contract BIM Execution Plan (BEP) was set to align roles, responsibilities, and Levels of Information Need. A Common Data Environment (CDE) underpinned collaboration, version control, and auditability, while automated checks and structured classification supported model quality and information compliance. For monitoring and control, business intelligence dashboards interrogate model data for QA/QC, while 360° photo records, captured via handheld and fixed site cameras, are used to assess models, verify progress and support work safety. Physical planning integrates 4D methods via a web interface linked to project schedules, enabling scenario analysis and transparent communication with stakeholders. Crucially, BIM/GIS integration with the municipal platform delivers a 3D web scene that fuses engineering and geospatial data for plan/profile analysis, in order to prevent conflicts with existing underground utilities and support location-aware decision, advancing Lisbon towards an operational digital twin. Results indicate fewer clashes and iterations, faster decisions, improved traceability, and clearer public communication. PGDL demonstrates how underground infrastructure, and digital governance can “connect communities” by making complex geotechnical works safer, more economical, more resilient, and more sustainable.

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