energies Review Autonomous Shuttle Bus for Public Transportation: A Review Calin Iclodean * , Nicolae Cordos and Bogdan Ovidiu Varga Department of Automotive Engineering and Transports, Technical University of Cluj-Napoca, 400001 Cluj-Napoca, Romania; [email protected] (N.C.); [email protected] (B.O.V.) * Correspondence: [email protected]; Tel.: +40-743-600-321 Received: 23 April 2020; Accepted: 4 June 2020; Published: 6 June 2020 Abstract: The rapid evolution of autonomous technology in the field of automotive and information technology (IT) has made it possible to implement autonomous vehicles (AVs) for public passenger transport. Although the shuttle bus transport capacities currently in use are low (maximum 15 people), the use of these transport units in large urban agglomerations is beneficial for society. The current paper is written to review the current AV implementation with respect to shuttle buses with its direct implications in their scientific evolution, with direct links to the legal and social aspects of public transportation all over the world. A critical aspect that is presented in the paper is the legal framework of autonomous driving, which is extremely uneven around the globe, with the direct impact of autonomous shuttle bus exploitation. As the legislation on AVs presents some shortcomings in the approval, registration, and public road implementation of these vehicles, many of the world’s major cities have found ways to integrate them into testing programs, establishing the basis for future comprehensive legislative measures in this highly dynamic scientific domain. The current technological solutions adopted by several autonomous shuttle bus producers will be presented with an exhaustive overview of each major component. The aspects of the control algorithm, with its complicated layers of security and perturbance factors, will be explained in detail. Thus, in some countries/cities, autonomous shuttle buses have been implemented on less-traveled routes where they can travel at speeds up to 25 km/h without hindering the public’s circulation, such as university campuses, industrial areas, airports, and sports bases. Some countries/cities use autonomous shuttle buses for pilot programs related to passenger transport, while others use them in postal transport and others for scientific purposes. In all of these situations, the first step in autonomous driving has been taken. The paper also makes an evaluation of the social factors that are a consequence of the mass introduction of autonomous driving as a means of public transportation. Autonomous shuttle buses are becoming a part of everyday life in big cities. Their acceptance as a strategic means of transport depends on their efficiency in daily services; through its efficiency, this means of transport will become a game-changer once its benefits become not only known but experienced by a large number of users. Keywords: autonomous vehicle; autonomous shuttle bus; public transportation; autonomous driving; game-changer 1. Introduction Public transport is one of the key issues in designing a large metropolitan area, one of the criteria that defines the quality of life in a city, and also strictly related to the social life of each inhabitant. A city without public transport would entail a random mass of people traveling in a random way without reaching their target. There are plenty of direct, indirect, and random factors that influence public transport, but by far the most disturbing one is human interaction in urban traffic. Drivers’ decisions Energies 2020, 13, 2917; doi:10.3390/en13112917 www.mdpi.com/journal/energies Energies 2020, 13, 2917 2 of 45 Energies 2020, 13, x FOR PEER REVIEW 2 of 46 are influenced by many factors and even though they are driving, driving is not always their only focus; theirsometimes only focus; drivers sometimes do not maintain drivers ado constant not maintain distance a constant between distance their vehicles, between do their not always vehicles, focus do noton signsalways and focus traffi con lights, signs doand not traffic follow lights, mandatory do not tra followffic rules mandatory and in their traffic decisions, rules and and in always their decisions,trust their and emotions. always If trust we eliminate their emotions. the human If we factor eliminate from thisthe equation,human factor we will from dramatically this equation, reduce we willtraffi dramaticallyc jams and increase reduce roadtraffic security. jams and Usually, increase a driverroad security. spends 45Usually, min to a 1driver h in tra spendsffic to reach45 min work to 1 hfrom in traffic home; to if thereach same work person from useshome; public if the transport same person (the conventional uses public mode),transport he (the or she conventional will spend mode),approximately he or she the will same spend amount approximately of time (including the same lane amount changing of time and (includ waitinging time). lane Inchanging the case and of a waitingdedicated time). line forIn the public case transportation, of a dedicated the line spent for timepublic according transportation, to several the studies spent [1time] will according decrease byto several40%–60%. studies [1] will decrease by 40%–60%. The configurationconfiguration ofof thesethese means means of of transport transport is highlyis highly similar similar to theto the general general platform platform of the of AVs,the AVs,yet there yet there are several are several differences differences that that differentiate differentiate them them and and these these aspects aspects have have been been pointed pointed out out in inthe the following following sections sections of of the the paper: paper: the the section section related related to to thethe powertrain,powertrain, thethe sectionsection related to the steering, the the section section related related to to the the braking, section section explaining explaining the the se sensorsnsors (the (the positioning, positioning, the the type, type, theirtheir coverage) coverage) all differ differ that the “classical” AV, autonomousautonomousdriving drivingalgorithm, algorithm, security. security. An overview of this this paper, paper, which contains the ma mainin objective of this paper and highlights all the chapters addressed during the review is presented in Figure1 1.. Autonomous vehicles Section 1 - introduction, general remarks Autonomous shutle bus Section 2 - technical charactersitics, powetrain configuration, steering, braking, sensors. Autonomous driving Autonomous shutle bus- Autonomous shutle bus- systems for shutle bus legal framework social implications Section 3 - alogorithm, control unit, safety Section 4 - US legal pespective, European Section 5 - social impact in direct relation and cybersecurity, routes. perspective, Chinese peespective. to the autonomous vehicles. Conclusions Section 6 - final evaluation of technical, legal and social implications. FigureFigure 1. AnAn overview overview of of the the paper. paper. The main advantage of autonomous driving is not only the replacement of the human driver The main advantage of autonomous driving is not only the replacement of the human driver with emotional and physical limitations, but the possibility of the vehicle to make predictions and to with emotional and physical limitations, but the possibility of the vehicle to make predictions and to communicate with infrastructure and other vehicles. Due to of this, AVs will become a key component communicate with infrastructure and other vehicles. Due to of this, AVs will become a key of the foundations of smart cities. Cities without traffic jams related to public transportation will component of the foundations of smart cities. Cities without traffic jams related to public rapidly increase their quality of life, decrease their energy consumption (in all components related to transportation will rapidly increase their quality of life, decrease their energy consumption (in all traffic), and also become more nature friendly in this manner, adding quality to their urban air. components related to traffic), and also become more nature friendly in this manner, adding quality Before talking about autonomous driving history, we have to talk about autonomous driving as a to their urban air. means of transport. History has shown that long before automobiles started being developed in this Before talking about autonomous driving history, we have to talk about autonomous driving as direction, the aeronautic industry and railroad industry successfully replaced (partially or fully) the a means of transport. History has shown that long before automobiles started being developed in this human intervention in the control of airplanes, trains, and subways. direction, the aeronautic industry and railroad industry successfully replaced (partially or fully) the human intervention in the control of airplanes, trains, and subways. The birth of autonomous driving was a complicated process, but it represented something exotic until only recently. This technology emerged behind the scenes without concrete applications to the economy of transport or to industry in general. Energies 2020, 13, 2917 3 of 45 The birth of autonomous driving was a complicated process, but it represented something exotic until only recently. This technology emerged behind the scenes without concrete applications to the economy of transport or to industry in general. In the mid-1920s, Francis P. Houldina, an electrical engineer with a military background, equipped a Chandler