An autonomous car, also known as a driverless car,driver-free car,self-driving car, or robot car is an autonomous vehicle capable of fulfilling the transportation capabilities of a traditional car. As an autonomous vehicle, it is capable of sensing its environment and navigating without human input. Robotic cars exist mainly as prototypes and demonstration systems. As of 2014[update], the only self-driving vehicles that are commercially available are open-air shuttles for pedestrian zones that operate at 12.5 miles per hour (20.1 km/h).
Autonomous vehicles sense their surroundings with such techniques as radar, lidar, GPS, and computer vision. Advanced control systems interpret sensory information to identify appropriate navigation paths, as well as obstacles and relevant signage. Some autonomous vehicles update their maps based on sensory input, allowing the vehicles to keep track of their position even when conditions change or when they enter uncharted environments.
The term "autonomous" is not a generally accepted term in science when used to describe technical artifacts. For example Wood et al. (2012), see reference below, writes "This Article generally uses the term “autonomous,” instead of the term “automated.” We have chosen to use the term “autonomous” because it is the term that is currently in more widespread use (and thus is more familiar to the general public). However, the latter term is arguably more accurate. “Automated” connotes control or operation by a machine, while “autonomous” connotes acting alone or independently. Most of the vehicle concepts (that we are currently aware of) have a person in the driver’s seat, utilize a communication connection to the Cloud or other vehicles, and do not independently select either destinations or routes for reaching them. Thus, the term “automated” would more accurately describe these vehicle concepts".
Level 3: The driver can fully cede control of all safety-critical functions in certain conditions. The car senses when conditions require the driver to retake control and provides a "sufficiently comfortable transition time" for the driver to do so.
Level 4: The vehicle performs all safety-critical functions for the entire trip, with the driver not expected to control the vehicle at any time. As this vehicle would control all functions from start to stop, including all parking functions, it could include unoccupied cars.
An increase in the use of autonomous cars would make possible such benefits as:
Fewer traffic collisions, due to an autonomous system's increased reliability and faster reaction time compared to human drivers.
Increased roadway capacity and reduced traffic congestion due to reduced need for safety gaps and the ability to better manage traffic flow.
Relief of vehicle occupants from driving and navigation chores.
Removal of constraints on occupants' state – in an autonomous car, it would not matter if the occupants were under age, over age, blind, distracted, intoxicated, or otherwise impaired.
Alleviation of parking scarcity, as cars could drop off passengers, park far away where space is not scarce, and return as needed to pick up passengers.
Elimination of redundant passengers – the robotic car could drive unoccupied to wherever it is required, such as to pick up passengers or to go in for maintenance. This would be especially relevant to trucks, taxis and car-sharing services.
Reduction of space required for vehicle parking.
Competition for the radio spectrum desired for the car's communication.
Self-driving cars could potentially be loaded with explosives and used as autonomous bombs.
Ethics: Ethical problems analogous to the trolley problem arise in situations where an autonomous car's software is forced during an unavoidable crash to choose between multiple harmful courses of action.
This M-1 vehicle detector was used at the first automatic driving demonstration in the United States, which took place in Lincoln in 1957.
Inspired by the efforts, the electric utility company, Central Power and Light Company, launched an advertorial that was posted on many leading newspapers throughout 1956 and 1957 and predicted autonomous cars: ELECTRICITY MAY BE THE DRIVER. One day your car may speed along an electric super-highway, its speed and steering automatically controlled by electronic devices embedded in the road. Highways will be made safe – by electricity! No traffic jams ... no collisions ... no driver fatigue
In 1925, Houdina Radio Control demonstrated the radio-controlled driverless car "linrrican Wonder" at New York City streets, traveling up Broadway and down Fifth Avenue through the thick of the traffic jam. The linrrican Wonder was a 1926 Chandler that was equipped with a transmitting antennae on the tonneau and was operated by a second car that followed it and sent out radio impulses which were caught by the transmitting antennae. The antennae introduced the signals to a circuit- breakers which operated small electric motors that directed every movement of the car. Achen Motor, a distributor of cars in Milwaukee and surrounding territory, used Francis' invention under the name "Phantom Auto" and demonstrated it in December 1926 at the streets of Milwaukee. It was demonstrated again in June 1932 at the streets of Fredericksburg as a feature attraction of Bigger Bargain Day in which most of the merchants of the city were participating.
In 1953, RCA Labs successfully built a miniature car that was guided and contolled by wires that were laid in a pattern on a laboratory floor. The system sparked the imagination of Leland M. Hancock, traffic engineer in the Nebraska Department of Roads, and of his director, L. N. Ress, state engineer. The decision was made to experiment with the system in actual highway installations. In 1958, a full size system was successfully demonstrated by RCA Labs and the State of Nebraska on a 400-foot strip of public highway just outside Lincoln, Neb. A series of experimental detector circuits buried in the pavement were a series of lights along the edge of the road. The detector circuits were able to send impulses to guide the car and determine the presence and velocity of any metallic vehicle on its surface. It was developed in collaboration with General Motors, who paired two standard models with equipment consisting of special radio receivers and audible and visual warning devices that were able to simulate automatic steering, accelerating and brake control. It was further demonstrated on 5 June 1960, at RCA Lab's headquarter in Princeton, New Jersey, where reporters were allowed to "drive" on the cars. Commercialization of the system was expected to happen by 1975. Also during the 1950s throughout the 1960s, General Motors showcased the Firebirds, a series of experimental cars that were described to have an "electronic guide system can rush it over an automatic highway while the driver relaxes".
In 1960, Ohio State University's Communication and Control Systems Laboratory launched a project to develop driverless cars which were activated by electronic devices imbedded in the roadway. Head of the project, Dr. Robert L. Cosgriff, claimed in 1966 that the system could be ready for installation on a public road in 15 years.
In the early 1960s, the Bureau of Public Roads considered the construction of an experimental electronically controlled highway. Four states - Ohio, Massachusetts, New York and California - were bidding for the construction.
During the 1960s, the United Kingdom's Transport and Road Research Laboratory tested a driverless Citroen DS that interacted with magnetic cables that were embedded in the road. It went through a test track at 80 miles per hour (130 km/h) without deviation of speed or direction in any weather conditions, and in a far more effective way than by human control. Research continued in the '70s with cruise control devices activated by signals in the cabling beneath the tracks. According to cost benefit analyses that were made, adoption of system on the British motorways would been repaid by end of the century, increase the road capacity by at least 50% and prevent around 40% of the accidents. Funding for these experiments was withdrawn by the mid-1970s.
Also during the 1960s and the 1970s, Bendix Corporation developed and tested autonomous cars that were powered and controlled by buried cables, with wayside communicators relaying computer messages.
In the same decade, the DARPA-funded Autonomous Land Vehicle (ALV) project in the United States made use of new technologies developed by the University of Maryland, Carnegie Mellon University, the Environmental Research Institute of Michigan, Martin Marietta and SRI International. The ALV project achieved the first road-following demonstration that used lidar, computer vision and autonomous robotic control to direct a robotic vehicle at speeds of up to 19 miles per hour (31 km/h). In 1987, HRL Laboratories (formerly Hughes Research Labs) demonstrated the first off-road map and sensor-based autonomous navigation on the ALV. The vehicle traveled over 2,000 feet (610 m) at 1.9 miles per hour (3.1 km/h) on complex terrain with steep slopes, ravines, large rocks, and vegetation.
In 1991, the United States Congress passed the ISTEA Transportation Authorization bill, which instructed USDOT to "demonstrate an automated vehicle and highway system by 1997." The Federal Highway Administration took on this task, first with a series of Precursor Systems Analsyes and then by establishing the National Automated Highway System Consortium (NAHSC). This cost-shared project was led by FHWA and General Motors, with Caltrans, Delco, Parsons Brinkerhoff, Bechtel, UC-Berkeley, Carnegie Mellon University, and Lockheed Martin as additional partners. Extensive systems engineering work and research culminated in Demo '97 on I-15 in San Diego, California, in which about 20 automated vehicles, including cars, buses, and trucks, were demonstrated to thousands of onlookers, attracting extensive media coverage. The demonstrations involved close-headway platooning intended to operate in segregated traffic, as well as "free agent" vehicles intended to operate in mixed traffic. Other carmakers were invited to demonstrate their systems, such that Toyota and Honda also participated. While the subsequent aim was to produce a system design to aid commercialization, the program was cancelled in the late 1990s due to tightening research budgets at USDOT. Overall funding for the program was in the range of $90 million.
In 1994, the twin robot vehicles VaMP and Vita-2 of Daimler-Benz and Ernst Dickmanns of UniBwM drove more than 620 miles (1,000 km) on a Paris three-lane highway in standard heavy traffic at speeds up to 81 miles per hour (130 km/h), albeit semi-autonomously with human interventions. They demonstrated autonomous driving in free lanes, convoy driving, and lane changes with autonomous passing of other cars. That same year, Lucas Industries developed parts for a semi-autonomous car in a project that was funded by Jaguar Cars, Lucas, and the UK Department of Trade and Industry.
In 1995, Dickmanns' re-engineered autonomous S-Class Mercedes-Benz undertook a 990 miles (1,590 km) journey from Munich in Bavaria, Germany to Copenhagen, Denmark and back, using saccadic computer vision and transputers to react in real time. The robot achieved speeds exceeding 109 miles per hour (175 km/h) on the German Autobahn, with a mean time between human interventions of 5.6 miles (9.0 km), or 95% autonomous driving. It drove in traffic, executing manoeuvres to pass other cars. Despite being a research system without emphasis on long distance reliability, it drove up to 98 miles (158 km) without human intervention.
In 1995, the Carnegie Mellon UniversityNavlab project achieved 98.2% autonomous driving on a 3,100 miles (5,000 km) cross-country journey which was dubbed "No Hands Across America". This car, however, was semi-autonomous by nature: it used neural networks to control the steering wheel, but throttle and brakes were human-controlled.
In 1996, (now Professor) Alberto Broggi of the University of Parma launched the ARGO Project, which worked on enabling a modified Lancia Thema to follow the normal (painted) lane marks in an unmodified highway. The culmination of the project was a journey of 1,200 miles (1,900 km) over six days on the motorways of northern Italy dubbed Mille Miglia in Automatico ("One thousand automatic miles"), with an average speed of 56 miles per hour (90 km/h). The car operated in fully automatic mode for 94% of its journey, with the longest automatic stretch being 34 miles (55 km). The vehicle had only two black-and-white low-cost video cameras on board and used stereoscopic vision algorithms to understand its environment.
Autonomous vehicles have also been used in mining. Since December 2008, Rio Tinto Alcan has been testing the Komatsu Autonomous Haulage System – the world's first commercial autonomous mining haulage system – in the Pilbara iron ore mine in Western Australia. Rio Tinto has reported benefits in health, safety, and productivity. In November 2011, Rio Tinto signed a deal to greatly expand its fleet of driverless trucks. Other autonomous mining systems include Sandvik Automine's underground loaders and Caterpillar Inc.'s autonomous hauling.
Many major automotive manufacturers, including General Motors, Ford, Mercedes Benz, Volkswagen, Audi, Nissan, Toyota, BMW, and Volvo, are testing driverless car systems as of 2013. BMW has been testing driverless systems since around 2005, while in 2010, Audi sent a driverless Audi TTS to the top of Pike’s Peak at close to race speeds. In 2011, GM created the EN-V (short for Electric Networked Vehicle), an autonomous electric urban vehicle. In 2012, Volkswagen began testing a "Temporary Auto Pilot" (TAP) system that will allow a car to drive itself at speeds of up to 80 miles per hour (130 km/h) on the highway. Ford has conducted extensive research into driverless systems and vehicular communication systems. In January 2013, Toyota demonstrated a partially self-driving car with numerous sensors and communication systems. Other programs in the field include the 2GetThere passenger vehicles from the Netherlands and the DARPA Grand Challenge in the USA; some plans for bimodal public transport systems include autonomous cars as a component.
In 2013, on July 12, VisLab conducted another pioneering test of autonomous vehicles, during which a robotic vehicle drove in downtown Parma with no human control, successfully navigating roundabouts, traffic lights, pedestrian crossings and other common hazards.
In 2011, the Freie Universität Berlin developed two autonomous cars to drive in the innercity traffic of Berlin in Germany. Led by the AutoNOMOS group, the two vehicles Spirit of Berlin and MadeInGermany handled intercity traffic, traffic lights and roundabouts between International Congress Centrum and Brandenburg Gate. It was the first car licensed for autonomous driving on the streets and highways in Germany and financed by the German Federal Ministry of Education and Research.
In August 2013 Nissan announced its plans to launch several driverless cars by 2020. The company is building in Japan a dedicated autonomous driving proving ground, to be completed in 2014. Nissan installed its autonomous car technology in a Nissan Leafall-electric car for demonstration purposes. The car was demonstrated at Nissan 360 test drive event held in California in August 2013. In September 2013, the Leaf fitted the prototype Advanced Driver Assistance System was granted a license plate that allows to drive it on Japanese public roads. The testing car will be used by Nissan engineers to evaluate how its in-house autonomous driving software performs in the real world. Time spent on public roads will help refine the car’s software for fully automated driving. The autonomous Leaf was demonstrated on public roads for the first time at a media event held in Japan in November 2013. The Leaf drove on the Sagami Expressway in Kanagawa prefecture, near Tokyo. Nissan vice chairman Toshiyuki Shiga and the prefecture’s Governor, Yuji Kuroiwa, rode in the car during the test.
Released in 2013, the 2014 Infiniti Q50 uses cameras, radar and other technology to deliver various lane-keeping, collision avoidance and cruise control features. One reviewer remarked, "With the Q50 managing its own speed and adjusting course, I could sit back and simply watch, even on mildly curving highways, for three or more miles at a stretch," adding that he wasn't touching the steering wheel or pedals.
Although as of 2013, fully autonomous vehicles are not yet available to the public, many contemporary car models have features offering limited autonomous functionality. These include adaptive cruise control, a system that monitors distances to adjacent vehicles in the same lane, adjusting the speed with the flow of traffic; lane assist, which monitors the vehicle's position in the lane, and either warns the driver when the vehicle is leaving its lane, or, less commonly, takes corrective actions; and parking assist, which assists the driver in the task of parallel parking.
In January 2014, Induct Technology's Navia shuttle became the first self-driving vehicle to be available for commercial sale. Limited to 12.5 miles per hour (20.1 km/h), the open-air electric vehicle resembles a golf cart and seats up to eight people. It is intended to shuttle people around "pedestrianized city centers, large industrial sites, airports, theme parks, university campuses or hospital complexes."
On May 27, 2014, Google announced plans to unveil 100 autonomous car prototypes built from scratch inside Google's secret X lab, as manifestations of years of work that began by modifying existing vehicles, along with, "in the next couple of years" according to Google in the above blog post, a pilot program similar to that which was used for the Cr-48 Chromebook back in 2010.
Major automobile manufacturers and technology companies have made numerous predictions for the development of autonomous car technology in the near future.
Late 2014, Volvo will feature Adaptive Cruise Control with steer assist which will automatically follow the vehicle ahead in queues. Mercedes already has it on some markets.
Late 2014, The National Telecommunications and Information Administration is expected to set recommendations for setting aside broadband spectrum for autonomous cars.
By 2015, Audi plans to market vehicles that can autonomously steer, accelerate and brake at lower speeds, such as in traffic jams.
By 2015, California will allow the testing of vehicles without wheels or pedals such as Google's on public roads. This will follow a 120-day grace period after a rule to be introduced in late 2014.
By Mid-2010's, Toyota plans to roll out near-autonomous vehicles dubbed Automated Highway Driving Assist with Lane Trace Control and Cooperative-adaptive Cruise Control.
By 2016, Mobileye expects to release hands-free driving technology for highways.
January 1, 2017 The National Highway Traffic Safety Administration hopes to mandate the adoption of Vehicle-to-Vehicle technology on all new automobiles.
By 2017, Tesla plans an "autopilot" feature that handles 90% of miles driven. Tesla has partnered with Mobileye.
By the 2017 model year, GM plans to offer a "super cruise" feature on select Cadillac models, with autonomous lane keeping, speed control, and brake control, so that parts of trips can be made without touching the wheel or pedals.
Between 2017 to 2020, Google believes its Level 4 self-driving cars will be available to the public.
By 2018, Nissan anticipates to have a feature that can allow the vehicle manoeuver its way on multi-lane highways.
By 2020, Volvo envisages having cars in which passengers would be immune from injuries.
By 2020, GM, Mercedes-Benz, Audi, Nissan, BMW and Renault all expect to sell vehicles that can drive themselves at least part of the time.
By 2025, Daimler and Ford expect autonomous vehicles on the market.
2035. IHS Automotive report says will be the year most self-driving vehicles will be operated completely independent from a human occupant’s control.
US States that allow driverless cars public road testing.
In the United States, state vehicle codes generally do not envisage — but do not necessarily prohibit — highly automated vehicles. To clarify the legal status of and otherwise regulate such vehicles, several states have enacted or are considering specific laws. As of the end of 2013, four U.S. states, (Nevada, Florida, California, and Michigan), along with the District of Columbia, have successfully enacted laws addressing autonomous vehicles.
In June 2011, the Nevada Legislature passed a law to authorize the use of autonomous cars. Nevada thus became the first jurisdiction in the world where autonomous vehicles might be legally operated on public roads. The bill was signed into law by Nevada's Governor on 16 June 2011. According to the law, the Nevada Department of Motor Vehicles (NDMV) is responsible for setting safety and performance standards and the agency is responsible for designating areas where autonomous cars may be tested. The law went into effect on 1 March 2012. This legislation was supported by Google in an effort to legally conduct further testing of its Google driverless car.
A Toyota Prius modified by Google to operate as a driverless car.
The Nevada law defines an autonomous vehicle to be "a motor vehicle that uses artificial intelligence, sensors and global positioning system coordinates to drive itself without the active intervention of a human operator." The law also acknowledges that the operator will not need to pay attention while the car is operating itself. Google had further lobbied for an exemption from a ban on distracted driving to permit occupants to send text messages while sitting behind the wheel, but this did not become law. Furthermore, Nevada's regulations require a person behind the wheel and one in the passenger’s seat during tests.
In May 2012, the Nevada Department of Motor Vehicles (DMV) issued the first license for a self-driven car to a Toyota Prius modified with Google's experimental driverless technology. Google's autonomous system permits a human driver to take control of the vehicle at any time by stepping on the brake or turning the wheel. License plates issued in Nevada for autonomous cars will have a red background and feature an infinity symbol (∞) on the left side, which, according to the DMV Director, "was the best way to represent the 'car of the future'."
On 1 July 2012, Florida became the second state to recognize the legality of autonomous vehicles. Florida's law clarifies that, "the State does not prohibit or specifically regulate the testing or operation of autonomous … vehicles on public roads."
On 25 September 2012, California Governor Jerry Brown signed a bill allowing the legalization of driverless cars in the state of California which also requires the California Department of Motor Vehicles to draft regulations by 2015. In California, proposed legislation would require that "the driver would still need to sit behind the wheel in case the robotic functions of the car suddenly fail and a real driver is needed", thus limiting the benefits that autonomous cars could provide to unlicensed drivers.
In the 2013–2014 legislative session, Colorado and Michigan introduced legislation addressing the regulation of autonomous vehicles. Governor Rick Snyder signed legislation allowing the testing of automated or self-driving vehicles on Michigan’s roads in December 2013, but requires a human in the driver seat at all time while the vehicle is in use. Colorado's proposed bill was rejected in committee in February 2013.
In 2013, the government of the United Kingdom permitted the testing of autonomous cars on public roads. Prior to this, all testing of robotic vehicles in the UK had been conducted on private property.
Individual vehicles may benefit from information obtained from other vehicles in the vicinity, especially information relating to traffic congestion and safety hazards. Vehicular communication systems use vehicles and roadside units as the communicating nodes in a peer-to-peer network, providing each other with information. As a cooperative approach, vehicular communication systems can allow all cooperating vehicles to be more effective. According to a 2010 study by the National Highway Traffic Safety Administration, vehicular communication systems could help avoid up to 81 percent of all traffic accidents.
In 2012, computer scientists at the University of Texas in Austin began developing smart intersections designed for autonomous cars. The intersections will have no traffic lights and no stop signs, instead using computer programs that will communicate directly with each car on the road.
Expert members of the Institute of Electrical and Electronics Engineers (IEEE) have estimated that up to 75% of all vehicles will be autonomous by 2040.
Navigant Research forecasts that autonomous vehicles will gradually gain traction in the market over the coming two decades and by 2035, sales of autonomous vehicles will reach 95.4 million annually, representing 75% of all light-duty vehicle sales.
ABI Research forecasts that truly self-driving cars would become a reality by 2020 and that 10 million such new cars would be rolling out on to United States' public highways every year by 2032.
Columbia University's The Earth Institute forecasts the reduction of United State's fleet of vehicles by a factor of 10.
PricewaterhouseCoopers forecasts a reduction of traffic accidents by a factor of 10 and it concludes that the fleet of vehicles in the United States may collapse from 245 million to just 2.4 million.
KPMG LLP and the Center for Automotive Research (CAR) foresee improvements in productivity and energy efficiency as well as new business models.
Public opinion surveys
In a 2011 online survey of 2,006 US and UK consumers by Accenture, 49% said they would be comfortable using a "driverless car".
A 2012 survey of 17,400 vehicle owners by J.D. Power and Associates found 37% initially said they would be interested in purchasing a fully autonomous car. However, that figure dropped to 20% if told the technology would cost $3,000 more.
In a 2012 survey of about 1,000 German drivers by automotive researcher Puls, 22% of the respondents had a positive attitude towards these cars, 10% were undecided, 44% were skeptical and 24% were hostile.
A 2013 survey of 1,500 consumers across 10 countries by Cisco Systems found a full 57% "stated they would be likely to ride in a car controlled entirely by technology that does not require a human driver", with Brazil, India and China the most willing to trust autonomous technology.
In a 2014 US telephone survey by Insurance.com, over three-quarters of licensed drivers said they would at least consider buying a self-driving car, rising to 86% if car insurance were cheaper. 31.7% said they would not continue to drive once an autonomous car was available instead.
The DARPA Grand Challenge has been held in 2004, 2005 and 2007 as an autonomous driving competition with millions of dollars in prize money.
The Google driverless car project maintains a test fleet of autonomous vehicles that has driven 300,000 miles (480,000 km) with no machine-caused accidents as of August 2012. By April 2014 700,000 autonomous miles (1,100,000 km) were logged.
The 2010 VIAC Challenge saw four autonomous vehicles drive from Italy to China on a 100-day 9,900-mile (15,900 km) trip with only limited human intervention, such as in traffic jams and when passing toll stations. At the time, this was the longest-ever journey conducted by an unmanned vehicle.
The ARGO vehicle (see History above) is the predecessor of the BRAiVE vehicle, both from the University of Parma's VisLab. Argo was developed in 1996 and demonstrated to the world in 1998; BRAiVE was developed in 2008 and demonstrated in 2009 at the IEEE IV conference in Xi'an, China.
In 2012, Stanford's Dynamic Design Lab, in collaboration with the Volkswagen Electronics Research Lab, produced Shelley, an Audi TTS designed for high speed (greater than 100 miles per hour (160 km/h)) on a racetrack course.
The Volkswagen Golf GTI 53+1 is a modified Volkswagen Golf GTI capable of autonomous driving. In his 2010 book, Democracy and the Common Wealth, Michael E. Arth claims that autonomous cars could become universally adopted if almost all private cars requiring drivers, which are not in use and parked 90% of the time, were traded for public self-driving taxis, which would be in near-constant use.
The 2002 film Minority Report, set in Washington, D.C. in 2054, features an extended chase sequence involving autonomous cars. The vehicle of protagonist John Anderton is transporting him when its systems are overridden by police in an attempt to bring him into custody.
The 2004 film I, Robot features autonomous vehicles driving on highways, allowing the car to travel safer at higher speeds than if manually controlled. The option to manually operate the vehicles is available.
The 2006 TV series NCIS season 4 epsode 11: Driven, features a robotic vehicle named "Otto," a part of a high level project of the Department of Defense, causes a death of a Navy Lieutenant, and then later almost kills Abby, the NCIS team must find out who sabotaged the vehicle and murdered the Navy Lieutenant.
The éX-Driver anime series features autonomous electric-powered vehicles driven by Artificial Intelligences (AI's). These sometime malfunction or are taken over by bad actors, requiring interception and intervention by éX-Drivers operating manually controlled gas-powered vehicles.
In "Sally" (first published May–June 1953), a short story by science fiction writer Isaac Asimov, autonomous cars have "positronic brains" and communicate via honking horns and slamming doors, and save their human caretaker.
^Gehrig, Stefan K.; Stein, Fridtjof J. (1999). "Dead reckoning and cartography using stereo vision for an autonomous car". IEEE/RSJ International Conference on Intelligent Robots and Systems 3. Kyongju. pp. 1507–1512. doi:10.1109/IROS.1999.811692. ISBN0-7803-5184-3.|accessdate= requires |url= (help)
^Arth, Michael E. (2010). Democracy and the Common Wealth: Breaking the Stranglehold of the Special Interests. Golden Apples Media. pp. 363–368. ISBN978-0-912467-12-2. Arth claims that this would be possible if almost all private cars requiring drivers, which are not in use and parked 90% of the time, would be traded for public self-driving taxis that would be in near-constant use.