Transportation Engineering (Jun 2020)
HeliRail: A railway-tube transportation system concept
Abstract
Helirail is an energy efficient mass transit transportation system concept, which combines developments in low-pressure tube transport with existing high-speed railway infrastructure. It addresses the problem that, currently at low speeds, steel wheel railways are an energy efficient transport mode, however at high speeds, >80% of energy is used overcoming drag. This means minimising these resistances presents a high-impact opportunity for reducing railway energy consumption. To reduce resistance, HeliRail consists of an airtight tube-track structure that allows existing steel-wheel trains to travel on existing railway corridors where slab-track is suitable, with minimal drag. The running environment is low-density heliox gas, held inside lightweight tubes, slightly below atmospheric pressure to minimise species transport. HeliRail captures this energy saving as an operational reduction, thus improving the energy efficiency of high speed rail by 60%. On a high capacity route, annually this could save enough energy to power 140,000 homes. Deploying Helirail on an existing line does not increase train cruising speeds, however a secondary benefit is journey time reduction, achieved using a small part of the energy saving for improved train acceleration. Unlike previous evacuated tube transportation embodiments, the system is interoperable with traditional rail lines/trains meaning vehicles can pass through HeliRail sections and onto traditional steel-rail networks. This also reduces land-purchase requirements. Further benefits include improved safety compared to vacuum transportation and fewer service disruptions compared to rail. Capital cost is low compared to a new rail or pressurised transportation line, and is recovered after a period competitive with renewable energy technologies.
