Abstract—The purpose of this research is investigating the usage of Autonomous Vehicles (AVs) in public transportation and proposing a new system using AVs and data sources to increase efficiency in public transportation provided by busses and taxis.
This paper states the parameters of AVs in public transportation and discusses how it will result in an efficient way of managing the public transportation according to collected data such as waiting passenger count, current traffic density, timetables etc. The words “autonomous” and “connected” can be used in this case, because the system that paper suggests, uses dynamic data also from current view (via multiple sensors) of the vehicle and other sources from the internet as it can come from other connected vehicles etc.
Index Terms—Autonomous vehicle (AV), traffic optimization, smart city, public transportation.
During the last years, the autonomous driving subject seems more popular than ever, as the technology improves and more companies announcing that the works have been started about this subject, it has become a hot topic. By 2020 companies like Audi, GM, Daimler, Mercedes-Benz, Nissan, BMW, and Renault expect to sell vehicles that are close to fully-autonomous driving. By 2035 it is predicted that most cars would be fully autonomous.  It has been a while for the semi-autonomous features that have been used in vehicles such as automatic braking, lane keeping etc. but the future of AVs seems more complicated. While the AVs world has some developments and works, there is no doubt that the autonomous vehicles issue would not affect public transportation. After widely usage of AVs in traffic, it will be impossible to consider using them in public transportation.
This research will be consisted of three main aspects of AVs in public transportation which are;
In Technology part, the features of AVs which provided by latest improvements in autonomous driving can be useful for public transportation and how they will be used in a matter will be discussed.
While debating the Optimization issues, beyond the general problems of AVs, it is especially will be investigated for public transportation and how it will affect the efficiency of managing it.
Lastly in Safety part, it will be discussed that if we can trust a vehicle that carries many passengers without a driver and what are the cases that should be considered.
Autonomous driving is one of the hottest topics in technology world in the last decade. Many companies work on new technologies and techniques to improve the efficiency and usage of the AVs.
The main concept is, an autonomous vehicle should operate without any human intervention. That appears new tasks to a vehicle, such as;
- Vehicle should sense its environment with multiple sensors and identify appropriate behaviors according to them. From sensing cars, pedestrians, road objects to weather conditions, many input should be detected by the vehicle.
- It should follow a navigation path. In the case of public transportation and proposed system, the navigation path can have multiple stops and instantaneous changes based on the information that is got from other data resources.
- The vehicle should follow the traffic rules.
- Unexpected situations should be handled. An odd behavior from a random pedestrian in the street or an accident should be recognized and the most suitable behavior of the vehicle should be applied.
This technology can be used in public transportation with a management system using different data sources and resulting an efficient system. These data can be used;
- Traffic Density. Bus routes are pre-determined and changes rarely. With the live traffic density data, bus route can be changed for maximizing the efficiency. In case of an accident which is on the bus route, or taxi’s route to destination, new calculated road can be a better solution to avoid the traffic jam and it definitely saves time.
- Passenger Density in Vehicles. This data can be gathered by using an observing technology in the vehicles. It will be used for distributing passenger numbers uniformly among the vehicles and lines.
- Bus Stop (Waiting) Passenger Density. This data can be gathered by using an observing technology at the bus/taxi stops. Measuring the crowd in the stops, will give data about demands for the numbers of vehicles that passes from the related stop.
- User Requests by a Mobile App. Waiting Passenger Destiny would not be useful when it is used solely, there can be many bus routes that passes from the same stop so destiny does not indicate how many passengers are waiting for a specific bus. Via a mobile application, bus line requests can be taken from the potential passengers.
- Vehicle Number and Timetable Data. For managing an efficient autonomous public transportation system, beyond the data that is collected from the sources must be coalesced with current numbers of vehicles and timetable data.
All these data that gathered and merged together, can be converted into a significant data which will be used in managing and optimization of an efficient public transportation system with autonomous vehicles.
In the system, buses and taxis are considered for the research and in the Figure 1, there are some differences mentioned in related vehicle types.
While comparing different type of public transportation AVs, there appears different properties. These properties are stated and compared as follows:
- Route. Bus routes are pre-determined and changes rarely. This provides an information about the behavior of AVs. An autonomous vehicle used for a taxi should be prepared for any destination that requested from the passenger and process it. In the case of buses, route is not a considerable problem as it appears in case of taxis. If we ignore the route changes in case of traffic jam or any related problems, changes in bus routes are not expected.
- Stops. Bus routes have many stops, although taxis have only two stop including departure and destination. In some occasions (for example in case of one of the passengers can get off at a location between departure and destination and taxi can continue its trip) there can me more than 2 stops but that will occur often. That results as different application styles of autonomous driving techniques in different type of vehicles when you consider about stops.
- Size. When we analyze in terms of maneuver capability and easiness of movement, taxis have much more advantages. As it is difficult for a human to drive a big vehicle like bus, same challenges (and more) appears when it becomes autonomous. For busses, it results as a disadvantage in the traffic on the contrary of capability of carrying many passengers. It will affect the behaviors of the vehicle, as it should maneuver differently in comparison of middle or small sized vehicles. For example; turning problems, changing lines, drawing close to bus stops.
Data from different sources must concentrate meaningfully, and can be used while targeting an efficient public transportation system with AVs usage. Without human drivers and with an internet connection to a management center, these AVs in a public transportation system can result in good scores.
We can catalogue optimized results within an efficient public transportation system with AVs;
- Route Optimizing. This can be done also in human controlled vehicles, but costs will be remarkably less while managing AVs.
- Human Factors. Both drivers and other staff, the cost of scheduling and asset utilization would be none.
- Controlled Vehicle Behaviors. Better control of measuring speed, acceleration and braking. This will result as better passenger safety and comfort through improved driving style.
IV. SAFETY AND RELIABILITY
Beyond the issues of AVs about safety and reliability, public transportation vehicles have other cases that should be considered. There exists further points that can affect both passengers, vehicles and all traffic around the vehicles.
We can examine these issues under two separate headline, as safety and reliability;
In AVs, there are basic safety issues that are associated with driving assistance attributes together :
- Vision enhancement
- Collision avoidance
- Lateral and Longitudinal collision avoidance
- Safety condition
- Pre-crash restraint development
- Automatic vehicle drive
These issues are also considered in public transportation vehicles, but there can vary other topics that should be studied.
Firstly, a public transportation vehicles (especially buses) have different maneuver styles and capabilities in comparison to personal AVs.
Secondly, Passenger get in/off the vehicle another issue. This includes, opening-closing doors and braking-speeding safely.
Lastly, another issue that related to ethical reasons, what should be the behavior of a 60 passenger carrying bus  in case of an unexpected situation? Discussions still continue what will be the behavior of an autonomous vehicle when to interfere with an accident. Essentially it is an important issue to consider, as it is explained in the paragraph below ;
“Here is the nature of the dilemma. Imagine that in the not-too-distant future, you own a self-driving car. One day, while you are driving along, an unfortunate set of events causes the car to head toward a crowd of 10 people crossing the road. It cannot stop in time but it can avoid killing 10 people by steering into a wall. However, this collision would kill you, the owner and occupant. What should it do?”
And when it comes to discuss for public transportation it becomes more complex and hard to solve. What will happen when a 59 passenger carrying bus heading toward a crowd of 60 people crossing the road? Should we assume that as a correct decision when the bus steers into a wall to save 60 people, but killing 59 people? Unless final decisions have been made the AVs will be remained unsecure for the most of people with these vague ethical issues.
Reliability issues are mostly related to security issues, by the evaluation of the passengers. This results consequential effects on the future of AVs in public transportation also.
In a survey  of 2000 people, %80 of survey respondents said they would not buy an autonomous car if one were available today. This is a strong reluctance when you consider the people habits in last decades evolving with technology. People had been started to follow latest trends, buying latest technology stuff and if they withstand a technology, it can be better stop and consider there may be some things going not well. There can be many reasons to people think like this, but it shows us it is a susceptible topic and should be considered carefully.
Even people have some trust issues with personal AVs, there are more complicated and harder problems to solve when it comes to subject of public transportation with AVs. Even so most of the people keep at a distance while considering buying an autonomous vehicle, think how they reflect using public transportation with AVs.
Lastly, a fragile issue to contemplate is the test results in the road tests. When people start to hear bad accidents, uncontrolled situations, unexplainable behaviors of AVs that can result as a stillborn technology with disappearing promises and future plans. Namely, it is a delicate subject to many people with skeptical questions in their mind.
There would not seem a future without autonomous vehicles, as the improvements and numbers confirmed.  AVs in public transportation figures as an inevitable development after seeing many personal vehicles around over the next years.
All over the world, especially in subway systems , autonomous vehicle systems are being used and while some of them need a human operator as helper, some of them operates without any human assistant. With developing technology and growing numbers of companies that are working on AVs, it would not take so long time to be used in public transportation systems. After consideration of the problems of AVs in public transportation that are mentioned and applying the recommended system in this research may lead an efficient usage.
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