V‑ROD GFRP Bars: Advancing Tunnel Breakthrough and Long-Term Durability.
The Hampton Roads Bridge-Tunnel Expansion Project, one of the largest infrastructure undertakings in Virginia, involves constructing new twin tunnels to alleviate traffic congestion between Hampton and Norfolk. A key innovation in this project is the use of Glass Fiber Reinforced Polymer (GFRP) bars in the “soft-eye” zones—strategically reinforced sections of diaphragm walls or secant piles that allow Tunnel Boring Machines (TBMs) to break through efficiently.
Unlike traditional steel rebar, GFRP bars are corrosion-resistant, lightweight, and cuttable, enabling TBMs to penetrate without damaging equipment or requiring manual removal of reinforcement. This significantly accelerates construction schedules and enhances safety. GFRP’s anisotropic properties—strong along the axis but easily abraded—make it ideal for temporary structures like soft-eyes, which may remain underground for decades without deterioration. The adoption of GFRP in Hampton Roads reflects a growing trend in tunnel engineering toward durable, low-maintenance materials that streamline operations.