Climate-Informed Schedule Risk Surfaces for Construction Planning in Türkiye: Linking Threshold Operability and Start-Date Optimization

Abstract

Climate change challenges the stationarity assumptions embedded in construction baseline schedules by shifting temperature and precipitation regimes and, consequently, weather-driven work interruptions. This study presents a gridded, data-driven workflow that links climate forcing to construction schedule outcomes by translating daily temperature/precipitation thresholds into Activity Performance Indices (APIs) for climate-sensitive activities and propagating them into project duration through start-date scanning. Historical baselines are represented using ERA5-Land reanalysis at 0.1° (~9 km) resolution, while future conditions are derived from a bias-corrected and downscaled CMIP6 multi-model ensemble under Shared Socioeconomic Pathways (with emphasis on SSP5-8.5 for end-of-century risk). Single- and multi-hazard operability surfaces are mapped across Türkiye and demonstrated using a 46-activity reinforced-concrete building schedule with a 207-day deterministic baseline. Results show strong seasonal redistribution of workability: warming tends to improve winter operability while degrading summer productivity, producing location- and start-date-dependent optimal windows. Nationally, climate effects increase the schedule mean/median to 255/238 days under historical conditions (+23% mean vs. baseline). Under far-future SSP5-8.5 (2071–2100), optimized outcomes converge to 239 days (+16% vs. baseline). If historical planning start dates are carried forward without climate adaptation, mean/median durations rise to 258/244 days, implying ~19 days (~10% of the baseline) of avoidable delay on average, with substantially larger penalties in some regions. The outputs support climate-aligned planning and provide an auditable basis for contract-ready baselines (e.g., via a Climate–Weather Baseline Report approach).