|Fig. 1: Concept model of Hyperloop. (Source: Wikimedia Commons)|
Elon Musk, the CEO of Tesla, Neuralink and Space X, is one of the greatest visionaries of this century, let alone history. One of his newest, most ambitious projects called the Hyperloop aims to create a transportation route between San Francisco and Los Angeles. This new effective transportation method would cost passengers $20 and take only a whopping 35 minutes rather than a 360 minute drive or 95 minute flight. To complete the desired trip, the Hyperloop would have to travel at a speed of 700 mph.  This is just under the speed of sound.
Musk expressed the desire to build a new mode of transportation after being disappointed by the states approval to build the California high speed rail bullet train from San Francisco to Los Angeles. The rail was budget at 70 billion dollars, yet be one of the slowest traveling bullet trains in the world. In addition, it would cost users more to ride, estimated at $105, than if they were to drive the expected route.  Musk believed it would be better to make a massive investment in the future of transportation in a fifth system of traveling other than car, planes, trains, and boats that met the following requirements.
|• Safer||• Immune to weather|
|• Faster||• Sustainably self powering|
|• Lower Cost||• Resistant to earthquakes|
|• More convenient||• Not disruptive to those along the route|
To meet these requirements, he proposed the Hyperloop. Musk came forward in August 2013 with an open source transportation concept to be vetted and further refined through public contribution.  The system consisted of two steel tubes welded side by side and suspended on pylons that would travel capsules (See Fig. 1). Similar to how old pneumatic tubes use to send mail and packages within and between buildings, the transportation system would work off of linear accelerators constructed along the length of the tube and strators on the capsule to transfer momentum.
Given the route would follow similar to the I-5, Musk believes the system would depart every two minutes (with potential to depart every 30 seconds at rush hour) carrying 38 passengers.  At the hourly rate of transporting 840 individuals per hour, it would meet the demand of the 6 million individuals who travel between SF and LA annually. The Hyperloop would travel two kinds of capsules: passenger and passenger + vehicles.  (See Table. 1)
|Table 1:Comparison of specification of the Passenger and Passenger + Vehicle Capsule|
When traveling at high speeds, the greatest power requirement comes from overcoming air resistance. Based on aerodynamic drag increasing with the square of speed, the power must increase by the cube of the speed. This means to make something travel twice as fast, it would require eight times the amount of power. To keep drag at a minimum, the capsule would have the least air resistance if it sit in a reduced pressure tube. This means the Hyperloop would operate at a pressure of 100 Pascals. This reduces the drag force of the air by 1,000 relative to sea level conditions and is equivalent to flying above 150,000 feet altitude.
The Hyperloop as a whole is projected to consume 28,000 hp or 37.5 MW.  Given one of the essential design components of the structure is having a solar array aligning the top of the entire system, it would self generate an annual average of 76,000 hp. The capsules travel speed is broken into 4 key categories. Take off (accelerating from 0 to 300 mph, coasting at 300 mph (through mountain ranges), high speed (300 mph - 760 mph along coasting section of I-5), and deceleration (300 mph - 0 mph). The Hyperloop would only pull energy from the solar arrays during the acceleration, coasting, and deceleration phases. During the high speed travel, it would pull energy from a set of large linear accelerators in combination with an inverter and inexpensive semiconductor switch.
The Hyperloop uses 1/16th and the amount of energy per passenger in commuting between the two cities in a car (~800 MJ) and 1/20th by plane (~1000 MJ).  The current most efficient way to travel between the two cities is by driving a Tesla Model S, however this method is still roughly five times less efficient. In addition to reducing total energy per traveler, the Hyperloop would also reduce CO2 emissions, air pollution, noise pollution, and number of accidents during travel between two locations. 
The most impressive thing about the vision of the Hyperloop is its chance of success in a timely matter. It is believed the project could be completed in 3 to 4 years and, in total, only cost 7 billion dollars, a tenth of the price of the California railway.  The Hyperloop is the next logical step for our future in preserving our natural resources, saving travelers time and money, and pushing the edge of technology. All technology faces resistance, the time is now to lean in to the Hyperloop.
© Valarie Allman. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 N. Davis, "Tesla Hyperloop," Physics 240, Stanford University, Fall 2014.
 J. Vranich and W. Cox, "California High Speed Rail: An Updated Due Diligence Report," Reason Foundation, April 2013.
 J. C. Chin et al., "Open-Source Conceptual Sizing Models for the Hyperloop Passenger Pod," American Institute of Aeronautics and Astronautics, AIEE-2015-1587, 5 Jan 15.
 M. Werner, K. Eissing, and S. Langton, "Shared Value Potential of Transporting Cargo via Hyperloop," Front. Built Environ. 2, 17 (2016).