Design Finalized for National Freeway 7 Kaohsiung Section: Incorporating New RC and UHPC for Lightweight Structures

According to a technical paper published in the August 2026 issue of the Journal of Civil and Hydraulic Engineering by officials from Taiwan's Freeway Bureau and CECI Engineering Consultants, the design for the National Freeway 7 Kaohsiung Section has been completed after a 4-year design phase. Spanning approximately 23 km—including 21 km of elevated viaducts and 2 km of at-grade roadway—the expressway starts at Nanxing Road, runs north along the east of Linhai Industrial Park, and links to National Freeway 10 in Renwu District. Featuring seven interchanges, it aims to segregate heavy freight traffic from urban corridors and alleviate congestion on Freeway 1 and Provincial Highway 88. To address construction labor shortages and lifecycle carbon reduction, the project integrates New RC and Ultra-High Performance Concrete (UHPC). The structural design pairs concrete strength fc' = 350 kgf/cm² with main reinforcement fy = 5,600 kgf/cm², achieving an estimated 12% reduction in rebar usage and 4% in project costs. Furthermore, Contract C705S marks Taiwan's first scaled implementation of UHPC in primary bridge structures. UHPC is deployed in 30–39m precast segmental U-girders at Siaogang Interchange, continuous link slabs that replace traditional expansion joints to prevent leakage and noise, and resilient expansion joint anchorage zones. Ecological conservation designs, such as painted-snipe wetland preservation and animal crossings, were also integrated.

Key takeaways

• The 23 km alignment (21 km viaduct, 2 km at-grade) features 7 interchanges, connecting Nanxing Road to Freeway 10 to segregate port freight from local traffic.
• New RC specifications (fc'=350 kgf/cm², fy=5,600 kgf/cm²) reduce rebar consumption by approximately 12% and construction cost by 4%.
• Contract C705S scales UHPC utilization across segmental precast U-girders, continuous link slabs, and durable expansion joint anchorage.
• The elevated route incorporates ecological measures, including greater painted-snipe habitat restoration at Daliao and five animal crossings in Siaogang.