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Efficiency of connected semi-autonomous platooning bus services in high-demand transit corridors
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.ORCID iD: 0000-0002-6859-6408
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.ORCID iD: 0000-0002-4106-3126
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The paper investigates the efficiency of serving high demand transit corridors with connected semi-autonomous busplatoons in both bus and BRT services. Platooning could make it possible to provide higher capacity than with conventionalbuses by forming virtual long buses out of multiple smaller vehicles, which could be particularly relevant inscenarios with large variation in demand between peak and off-peak hours. The problem is formulated as a constrainedoptimization problem to minimize total system cost, which includes waiting cost, access cost, riding cost, operatingcost and capital cost. For single period with fixed demand, both analytical solutions and numerical examples areprovided. Sensitivity analysis is carried out with regard to demand levels and capacity upper bound. The problemis generalized to a two-period problem considering peak and off-peak demand. Numerical results are provided withsensitivity analysis regarding average demand level and ratio of peak/off-peak demand. Furthermore, the impact of alower bound on service headway is investigated. The result shows that semi-autonomous vehicle platooning is competitivein medium and high demand scenarios, with the potential of reduced users’ cost and operator’s operating costat the expense of additional rolling stock cost. The minimum headway, restricted vehicle size, and higher demandratio all make semi-autonomous platooning more advantageous.

National Category
Transport Systems and Logistics
Identifiers
URN: urn:nbn:se:kth:diva-251621OAI: oai:DiVA.org:kth-251621DiVA, id: diva2:1316106
Funder
TrenOp, Transport Research Environment with Novel Perspectives
Note

QC 20190520

Available from: 2019-05-16 Created: 2019-05-16 Last updated: 2019-05-20Bibliographically approved
In thesis
1. Planning and evaluation of autonomous vehicles in freight and public transport services
Open this publication in new window or tab >>Planning and evaluation of autonomous vehicles in freight and public transport services
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The introduction of automation technology in transport systems brings both opportunities and challenges. The direct benefits of automation technology are obvious, for instance, reduced marginal driving cost, improved energy efficiency and increased safety. However, factors such as additional vehicle acquisition cost might hinder the implementation of autonomous vehicles, especially in the early stages when mass production is not realized yet. Besides, some benefits require large-scale applications or cooperation among multiple vehicles, while the low market penetration rate of autonomous vehicles may make system-specific benefits insignificant. Without proper planning and operation schemes, the advantages of automation technology can be cancelled out by its disadvantages. Given that the advantages of individual autonomous vehicles have been extensively explored, it is necessary to estimate the efficiency of transport systems involving autonomous vehicles. This thesis intends to solve the operation problem of autonomous vehicles in freight and public transport systems, focusing on system cost analysis.

In freight transport, semi-autonomous truck platooning is a promising way to reduce fuel consumption. By instructing vehicles to form groups and drive together closely, the trailing vehicles experience reduced air resistance from the leading vehicle, and thus less fuel consumption. However, in practice, freight transport companies should also take time windows and transport reliability into consideration. The study answers the questions whether platoons should be formed and how significant can the savings be, considering driving cost, predefined time windows, travel time uncertainty and fuel cost. System optimization techniques, including stochastic optimization and mixed-integer linear programming, are adopted to minimize the total cost.

In public transport, autonomous buses are assumed to save on-board crew cost, partially or fully. Similar with truck platoons, semi-autonomous buses can also form bus platoons for the purpose of eliminating the drivers from trailing buses. By contrast, fully autonomous buses are completely driverless and operates individually like conventional buses. To investigate the efficiency of autonomous buses, we compare the total cost of autonomous buses with conventional buses, where both passengers’ cost and service provider’s cost are modelled. In a general trunk-and-branches network connecting city center and suburbs, both fully autonomous bus and semi-autonomous bus systems are assessed. On a simple highly demanded corridor where demand varies during peak and off-peak hours, semi-autonomous bus platoons can be used as trains by extending its capacity in peak hours. Application of semi-autonomous vehicles are considered in traditional bus transit and BRT, by comparing with its conventional opponents.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. p. iii-xiv, 35
Series
TRITA-ABE-DLT ; 1921
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-251681 (URN)978-91-7873-237-1 (ISBN)
Public defence
2019-06-12, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20190520

Available from: 2019-05-20 Created: 2019-05-17 Last updated: 2019-05-24Bibliographically approved

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