Low-Risk High-Reward Transition to Low Pressure Tunnel Transit

Typical low-pressure tunnel transit concepts rely on fully separated tube networks, causing added time and cost for passengers to transfer between existing surface transit and tunnel systems. This paper evaluates a multimodal ground-effect flight technology (GEFT) that enables seamless open-entry operation between highways, railways, and low-pressure tunnels, eliminating the need for isolated tube corridors. Using computational fluid dynamics, the study shows that as vehicle velocity increases in tunnels, the tunnel pressure can be engineered to decrease at a rate comparable to the increase in dynamic pressure, allowing the creation of beneficial tailwinds that improve speed and energy efficiency. Results indicate that open-entry, lower-pressure tunnel transit using GEFT can be competitive with conventional and closed-tube systems over distances up to at least 1000 miles. Closed, fully evacuated tunnel systems may offer advantages over about 2000 miles, but the paper argues that continuous incremental improvement of open-entry systems may delay or prevent closed systems from having clear advantages at any distance.