Review Article

Fully Autonomous Buses: A Literature Review and Future Research Directions

Table 1

Key studies on technology aspects of autonomous buses.

Author(s) (year)TypeLocationMethodsKey findings

Villagra et al. (2012)JournalEuropeSimulation and testing (vehicle on a test track)(i) A planning algorithm was proposed and resulted in smooth driving in terms of comfort and efficiency
(ii) This was compared to manual driving on a test track and the results were reasonable

Lam & Katupitiya (2013)Conference proceedingEuropeSimulation (using a nonlinear dynamic model and a path-following and car-following model for platooning)(i) The proposed model of platooning is well-behaved with acceptable error interaction in a complex vehicle-road system

Lam et al. (2016)JournalAustraliaSimulation (employing AV in public transportation network)(i) A reliable representation of the real system utilizing autonomous buses and covering various technologies such as schedule-free dispatch or autonomous intersection management illustrates the performance of the transit network

Lutin & Kornhauser (2014)Conference proceeding (TRB)United StatesCase study (cost and benefit analysis and capacity analysis for one transit agency)(i) The implementation of collision avoidance technology on buses can be cost effective
(ii) Cooperative adaptive cruise control (CACC) can increase the capacity of an exclusive bus lane
(iii) Collision avoidance and CACC are promising technologies

Lutin et al. (2016)Conference proceeding (TRB)United StatesSafety analysis and export opinion with road map(i) Safety analysis showed the number of bus-related injuries, casualties, and liability expenses is currently increasing
(ii) The proposed road map calls for partnerships between stakeholders
(iii) The authors call for more research on technologies such as autonomous collision avoidance and autonomous emergency braking

Polzin (2016)White paperUnited StatesPosition paper/expert opinion(i) Autonomous buses could enable increased performance in terms of vehicle speed and passenger volumes (like bus rapid transit)
(ii) Automation technology could significantly change travel time and monetary costs

Pessaro (2016)ReportUnited States and Europeāˆ—Case studies (five demonstration projects)(i) Three of five case studies are European, and they are at the forefront of testing autonomous buses in real-world situations
(ii) Two of five case studies are in the United States but are still in the planning stages (pre-deployment)
(iii) Europeans are leaders (compared to Americans) in manufacturing and deploying autonomous bus technology

Sinner & Weidmann (2017)Conference proceedingEuropeDefinition/concept paper (comparison of automated bus and train system)(i) When considering automation in the future, the line capacities of bus and train systems are similar
(ii) Future train systems likely have greater station capacity due to longer vehicle lengths, but they require higher infrastructure cost

Sinner et al. (2017)Conference proceeding (TRB)EuropeDefinition/concept paper (definitions of bus and train in age of automation)(i) With automation, transit vehicles are not steered by humans any more
(ii) The key element defining future buses is compatibility with ordinary road traffic (mixed traffic) without needing mechanical guidance

Ginn et al. (2017)JournalUnited StatesDesign/prototype (slim semiautonomous bus rapid transit concept)(i) The advantages of the proposed bus rapid transit system are decreased operational costs due to narrower bus body sizes and modularity of the vehicles
(ii) The disadvantage of the proposed system is that the implementation cost could be high

Montes et al. (2017)JournalEuropeDesign/experiment (of automatic control for articulated buses)(i) The experimental testing of three separate control systems (velocity, steering, and safety) yielded good results

Gao et al. (2018)Conference proceeding (TRB)United StatesSimulation (data-driven CACC algorithm)(i) The proposed algorithm has the capability to increase transit vehicle throughput
(ii) The method has better performance in theory and practice than previous control methods

āˆ—Discusses CityMobil2 Project.