Theory and operation

Developments in high-speed rail have historically been impeded by the difficulties in managing friction and air resistance,citation needed both of which become substantial when vehicles approach high speeds. The vactrain concept theoretically eliminates these obstacles by employing magnetically levitating trains in evacuated (airless) or partly evacuated tubes, allowing for speeds of thousands of miles per hour. However, the high cost of maglev and the difficulty of maintaining a vacuum over large distances has prevented this type of system from ever being built. The Hyperloop resembles a vactrain system but operates at approximately one millibar (100 Pa) of pressure.

Initial design conceptedit

The Hyperloop concept operates by sending specially designed "capsules" or "pods" through a steel tube maintained at a partial vacuum. In Musk's original concept, each capsule floats on a 0.02–0.05 in (0.5–1.3 mm) layer of air provided under pressure to air-caster "skis", similar to how pucks are levitated above an air hockey table, while still allowing higher speeds than wheels can sustain. Hyperloop One's technology uses passive maglev for the same purpose. Linear induction motors located along the tube would accelerate and decelerate the capsule to the appropriate speed for each section of the tube route. With rolling resistance eliminated and air resistance greatly reduced, the capsules can glide for the bulk of the journey. In Musk's original Hyperloop concept, an electrically driven inlet fan and axial compressor would be placed at the nose of the capsule to "actively transfer high-pressure air from the front to the rear of the vessel", resolving the problem of air pressure building in front of the vehicle, slowing it down. A fraction of the air is shunted to the skis for additional pressure, augmenting that gain passively from lift due to their shape. Hyperloop One's system does away with the compressor.

In the alpha-level concept, passenger-only pods are to be 7 ft 4 in (2.23 m) in diameter and are projected to reach a top speed of 760 mph (1,220 km/h) to maintain aerodynamic efficiency. (Section 4.4) The design proposes passengers experience a maximum inertial acceleration of 0.5 g, about 2 or 3 times that of a commercial airliner on takeoff and landing.

Proposed routesedit

A number of routes have been proposed for Hyperloop systems that meet the approximate distance conditions for which a Hyperloop is hypothesized to provide improved transport times (distances of under approximately 1,500 kilometres (930 miles)). Route proposals range from speculation described in company releases to business cases to signed agreements.

United States

The route suggested in the 2013 alpha-level design document was from the Greater Los Angeles Area to the San Francisco Bay Area. That conceptual system would begin around Sylmar, just south of the Tejon Pass, follow Interstate 5 to the north, and arrive near Hayward on the east side of San Francisco Bay. Several proposed branches were also shown in the design document, including Sacramento, Anaheim, San Diego, and Las Vegas.

No work has been done on the route proposed in Musk's alpha-design; one cited reason is that it would terminate on the fringes of the two major metropolitan areas (Los Angeles and San Francisco), resulting in significant cost savings in construction, but requiring that passengers traveling to and from Downtown Los Angeles and San Francisco, and any other community beyond Sylmar and Hayward, to transfer to another transportation mode in order to reach their final destination. This would significantly lengthen the total travel time to those destinations.

A similar problem already affects present-day air travel, where on short routes (like LAX-SFO) the flight time is only a rather small part of door to door travel time. Critics have argued that this would significantly reduce the proposed cost and/or time savings of Hyperloop as compared to the California High-Speed Rail project that will serve downtown stations in both San Francisco and Los Angeles. Passengers travelling from financial center to financial center are estimated to save about two hours by taking the Hyperloop instead of driving the whole distance.

Others questioned the cost projections for the suggested California route. Some transportation engineers argued in 2013 that they found the alpha-level design cost estimates unrealistically low given the scale of construction and reliance on unproven technology. The technological and economic feasibility of the idea is unproven and a subject of significant debate.

In November 2017, Arrivo announced a plan for a maglev automobile transport system from Aurora, Colorado to Denver International Airport, the first leg of a system from downtown Denver. Its contract describes completion of the first leg in 2021. In February 2018, Hyperloop Transportation Technologies announced a similar plan for a loop connecting Chicago and Cleveland and a loop connecting Washington and New York City.

In 2018 the Missouri Hyperloop Coalition was formed between Virgin Hyperloop One, the University of Missouri, and engineering firm Black & Veatch to study a proposed route connecting St. Louis, Columbia, and Kansas City.

On 19 December 2018, Elon Musk unveiled a 2-mile (3 km) tunnel below Los Angeles. In the presentation, a Tesla Model X drove in a tunnel on the predefined track (rather than in a low-pressure tube). According to Musk the costs for the system are US$10 million. Musk said: "The Loop is a stepping stone toward Hyperloop. The Loop is for transport within a city. Hyperloop is for transport between cities, and that would go much faster than 150 mph."

The Northeast Ohio Areawide Coordinating Agency, or NOACA, has partnered with Hyperloop Transportation Technologies to conduct a $1.3 million feasibility study for developing a Hyperloop corridor route from Chicago to Cleveland and Pittsburgh for America’s first multistate hyperloop system in the Great Lakes Megaregion. Hundreds of thousands of dollars already have been committed to the project. NOACA’s Board of Directors has awarded a $550,029 contract to Transportation Economics & Management Systems, Inc. (TEMS) for the Great Lakes Hyperloop Feasibility Study to evaluate the feasibility of an ultra-high-speed Hyperloop passenger and freight transport system initially linking Cleveland and Chicago.

India

Hyperloop Transportation Technologies are in process to sign a Letter of Intent with the Indian Government for a proposed route between Chennai and Bengaluru. If things go as planned, the distance of 345 km could be covered in 30 minutes. HTT also signed an agreement with Andhra Pradesh government to build India's first Hyperloop project connecting Amaravathi to Vijayawada in a 6-minute ride.

On 22 February 2018, Hyperloop One has entered into a MOU (Memorandum of Understanding) with the Government of Maharashtra to build a hyperloop transportation system between Mumbai and Pune that would cut the travel time from the current 180 minutes to just 20 minutes.

Indore-based Dinclix GroundWorks' DGWHyperloop advocates a Hyperloop corridor between Mumbai and Delhi, via Indore, Kota, and Jaipur.

Elsewhere

Many of the active Hyperloop routes being planned currently are outside of the U.S. Hyperloop One published the world's first detailed business case for a 300-mile (500 km) route between Helsinki and Stockholm, which would tunnel under the Baltic Sea to connect the two capitals in under 30 minutes. Hyperloop One is also well underway on a feasibility study with DP World to move containers from its Port of Jebel Ali in Dubai. Hyperloop One on 8 November 2016, announced a new feasibility study with Dubai's Roads and Transport Authority for passenger and freight routes connecting Dubai with the greater United Arab Emirates. Hyperloop One is also working on passenger routes in Moscow and a cargo Hyperloop to connect Hunchun in north-eastern China to the Port of Zarubino, near Vladivostok and the North Korean border on Russia's Far East. In May 2016, Hyperloop One kicked off their Global Challenge with a call for comprehensive proposals of hyperloop networks around the world. In September 2017, Hyperloop One selected 10 routes from 35 of the strongest proposals: Toronto–Montreal, Cheyenne–Denver–Pueblo, Miami–Orlando, Dallas–Laredo–Houston, Chicago–Columbus–Pittsburgh, Mexico City–Guadalajara, Edinburgh–London, Glasgow–Liverpool, Bengaluru–Chennai, and Mumbai–Chennai.

Others have put forward European routes, including a route beginning at Amsterdam or Schiphol to Frankfurt proposed by Hardt Hyperloop. A Warsaw University of Technology team is evaluating potential routes from Cracow to Gdańsk across Poland proposed by Hyper Poland.

TransPod is exploring the possibility of Hyperloop routes which would connect Toronto and Montreal, Toronto to Windsor, and Calgary to Edmonton. Toronto and Montreal, the largest cities in Canada, are currently connected by Ontario Highway 401, the busiest highway in North America. In March 2019, Transport Canada commissioned the study of the Hyperloop, so it can be “better informed on the technical, operational, economic, safety, and regulatory aspects of the Hyperloop and understand its construction requirements and commercial feasibility.”

Hyperloop Transportation Technologies (HTT) reportedly signed an agreement with the government of Slovakia in March 2016 to perform impact studies, with potential links between Bratislava, Vienna, and Budapest, but there have been no developments on that since. In January 2017, HTT signed an agreement to explore the route Bratislava—Brno—Prague in Central Europe.

In 2017, SINTEF, the largest independent research organization in Scandinavia, announced they are considering building a test lab for Hyperloop in Norway.

An agreement was signed in June 2017 to co-develop a hyperloop line between Seoul and Busan in South Korea.

Open-source design evolutionedit

In September 2013, Ansys Corporation ran computational fluid dynamics simulations to model the aerodynamics of the capsule and shear stress forces that the capsule would be subjected to. The simulation showed that the capsule design would need to be significantly reshaped to avoid creating supersonic airflow, and that the gap between the tube wall and capsule would need to be larger. Ansys employee Sandeep Sovani said the simulation showed that Hyperloop has challenges but that he is convinced it is feasible.

In October 2013, the development team of the OpenMDAO software framework released an unfinished, conceptual open-source model of parts of the Hyperloop's propulsion system. The team asserted that the model demonstrated the concept's feasibility, although the tube would need to be 13 feet (4 m) in diameter, significantly larger than originally projected. However, the team's model is not a true working model of the propulsion system, as it did not account for a wide range of technological factors required to physically construct a Hyperloop based on Musk's concept, and in particular had no significant estimations of component weight.

In November 2013, MathWorks analyzed the proposal's suggested route and concluded that the route was mainly feasible. The analysis focused on the acceleration experienced by passengers and the necessary deviations from public roads in order to keep the accelerations reasonable; it did highlight that maintaining a trajectory along I-580 east of San Francisco at the planned speeds was not possible without significant deviation into heavily populated areas.

In January 2015, a paper based on the NASA OpenMDAO open-source model reiterated the need for a larger diameter tube and a reduced cruise speed closer to Mach 0.85. It recommended removing on-board heat exchangers based on thermal models of the interactions between the compressor cycle, tube, and ambient environment. The compression cycle would only contribute 5% of the heat added to the tube, with 95% of the heat attributed to radiation and convection into the tube. The weight and volume penalty of on-board heat exchangers would not be worth the minor benefit, and regardless the steady-state temperature in the tube would only reach 30–40 °F (17–22 °C) above ambient temperature.

According to Musk, various aspects of the Hyperloop have technology applications to other Musk interests, including surface transportation on Mars and electric jet propulsion.

Researchers associated with MIT's department of Aeronautics and Astronautics published research in June 2017 that verified the challenge of aerodynamic design near the Kantrowitz limit that had been theorized in the original SpaceX Alpha-design concept released in 2013.

In 2017, Dr. Richard Geddes and others formed the Hyperloop Advanced Research Partnership to act as a clearinghouse of Hyperloop public domain reports and data.

In February 2020, Hardt Hyperloop, Hyper Poland, TransPod and Zeleros formed a consortium to drive standardisation efforts, as part of a joint technical committee (JTC20) set up by European standards bodies CEN and CENELEC to develop common standards aimed at ensuring the safety and interoperability of infrastructure, rolling stock, signalling and other systems.

Marsedit

According to Musk, Hyperloop would be useful on Mars as no tubes would be needed because Mars' atmosphere is about 1% the density of the Earth's at sea level. For the Hyperloop concept to work on Earth, low-pressure tubes are required to reduce air resistance. However, if they were to be built on Mars, the lower air resistance would allow a Hyperloop to be created with no tube, only a track.