The endless traffic jams and the increasing number of vehicles in cities have compelled humankind to look for alternatives other than roads. Apart from air travel, a growing number of engineers and enthusiasts have discovered a huge potential in underground transportation and find it to be a lucrative and swift option.
One such initiative is being taken by Elon Musk’s The Boring Company (TBC), which is developing a series of loops across the US. The company is already working on a loop system for the Las Vegas Convention Center. At the same time, its initial test tunnel located in California is being used for the research and development of its loop and hyperloop systems.
A loop is an all-electric, high-speed underground public transportation system to transport passengers via compatible Autonomous Electric Vehicles (AEVs). The zero-emissions system can operate at a speed of up to 241 km/h.
A hyperloop can be defined as an ultra-high-speed underground public transportation system that can operate at a speed of 965+ km/h within a vacuum-sealed tunnel. The major difference between a loop and a hyperloop is that the loop is used for shorter intra-city routes, whereas hyperloops are meant for longer inter-city routes.
General Details of TBC Loops
The concept of the loop is quite simple—take a normal car and turn it into a passively stable vehicle by adding deployable tracking wheels, stabilizing wheels, allowing it to travel at high speed through a small tunnel.
TBC will employ the Tesla Model S, 3, and X vehicles to operate autonomously within the loop system.
The passenger capacity of the loop depends on the number, size, and spacing of stations, but a high-volume loop system can transport a whopping number of 10,000 people in an hour. Additional tunnels can be constructed for greater ridership, however, for lower ridership, the tunnel system will remain the same, but smaller and less expensive stations can be built.
The system has three types of stations, i.e., surface stations, subsurface stations, and subsurface open-air stations. There would also be no limit to the number of stations along the tunnel route; a station can be as small as two parking spaces or larger based on the ridership capacity.
Due to their small footprint, the stations can be easily integrated in busy city centers, parking garages, and residential communities. This will help increase the density of the stations, thereby distributing the AEVs and foot traffic across several access points, resulting in a greater number of entry and exit points to reduce congestion in populated areas.
The loop transports the passengers directly to their final destination without stopping in between; it travels through a main artery tunnel and uses the side tunnels for entry/exit of the AEVs. However, the TBC’s tunnels are designed and built with the intention to eventually transition to hyperloops.
Another remarkable feature of the system is that the loop vehicles can carry small numbers of passengers (as low as one), unlike standard public transportation systems. This allows passengers to travel with their acquaintances while also reducing the risk of exposure to airborne diseases.
This is especially very useful in today’s pandemic-stricken world. The rider high-touch surfaces can easily be detected within the AEVs and can then be cleaned and disinfected between rides.
The loop tunnels have an inner diameter of 12 feet, with a length ranging from 0.25 mile (0.4 km) to infinite but with a requirement of at least two stations.
The loop tunnels have a typical minimum depth of 30 feet, i.e., well beneath most utilities on the surface. If in case, a utility is located deeper, the tunnel depth is increased accordingly.
For digging the loop tunnels, TBC has been using three generations of tunnel boring machines (TBMs), namely, Godot (off-the-shelf TBM), Godot+ (50% faster than Godot), and Prufrock, which can achieve speeds of more than 10x faster than Godot.
Each of these TBMs was developed with the intention to increase the tunneling speed while reducing the cost. TBC’s loop tunnels are currently priced at approximately $10 million per mile, which is significantly lower than other such projects.
Standard TBMs take 8-12 weeks for digging one mile, whereas Prufrock has been designed to dig more than one mile per week, with a longer-term goal of 7 miles per day.
Another useful feature is that Prufrock can be launched directly from the surface, phasing out the need for a TBM launch pit, which is both expensive and slow. Prufrock can be transported on a truck to start tunneling within 48 hours. Porpoising allows Prufrock to emerge at-grade without the need for excavating an expensive TBM retrieval pit.
With Prufrock, the tunnel’s precast segments can be installed simultaneously with digging, eliminating the need to stop the TBM every 5 feet that is a standard on soft-soil TBMs.
The chosen AEVs for the project have achieved the National Highway Traffic Safety Administration’s (NHTSA) 5 star-rating with the lowest probability of injury among all the tested vehicles.
The loop tunnels will have emergency exits along the tunnel route. The system has no internal hazards, and the entire paved surface serves as an emergency walkway.
The tunnel lining is made up of concrete, which is non-flammable; therefore, the risk of a fire is significantly low. It has no live electric third rail, thus reducing potential fire sources and eliminating the potentially dangerous effects of water intrusion. The AEVs are also designed to handle some amount of rain safely.
The tunnel’s ventilation system is designed as per National Fire Protection Association (NFPA) standards and can remove smoke to allow safe evacuation in case of an unlikely fire.
Other safety features include a wide walkway for emergency egress, real-time gas and smoke detection, direct communications within the tunnel to the control center via tunnel intercoms, cell service, and WiFi.
A loop is an all-electric, high-speed underground public transportation system to transport passengers via compatible autonomous electric vehicles (AEVs).
A hyperloop is an ultra-high speed underground public transportation system that can operate at a speed of 965+ km/h within a vacuum-sealed tunnel.
The maximum speed at which one can travel in a loop is 241 km/h.
Loops are being constructed by Elon Musk's The Boring Company.