Construction-led agglomeration: an SCGE-project scheduling framework for evaluating highway development timing, regional construction capacity, and lifecycle performance

This study develops an integrated framework that couples a spatial computable general equilibrium (SCGE) model with agglomeration economies to an explicit representation of the construction sector and highway project pipeline. A 20-year, 12-region highway corridor program is analyzed under three strategies: front-loaded phasing, with 60% of lane-kilometers built in the first decade; balanced phasing, with work evenly distributed over four five-year periods; back-loaded “big-bang” delivery, with 70% of work in the final decade. Relative to back-loaded delivery, front-loaded phasing increases construction value added by 9.3%, reduces user travel time by 14.8%, and raises long-run GDP by 4.1%, but induces peak labor shortages that push construction wages up by 7.6% and bid prices by 5.2%. Balanced phasing produces a smoother workload, cutting the standard deviation of construction employment by 38% relative to front-loaded delivery while yielding 11.2% lower discounted travel-time costs than back-loaded delivery. Incorporating embodied emissions and induced traffic shows balanced phasing reduces lifecycle CO2 by 6.5% through earlier adoption of low-carbon technologies and more even utilization of equipment. The framework offers an industry-oriented decision tool for co-designing, timing, sequencing, and capacity-building to optimize construction markets, network performance, and long-run spatial development.