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Planning and evaluation of autonomous vehicles in freight and public transport services
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.ORCID iD: 0000-0002-6859-6408
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: urn:nbn:se:kth:diva-251681ISBN: 978-91-7873-237-1 (print)OAI: oai:DiVA.org:kth-251681DiVA, id: diva2:1316459
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
List of papers
1. Freight transport platoon coordination and departure time scheduling under travel time uncertainty
Open this publication in new window or tab >>Freight transport platoon coordination and departure time scheduling under travel time uncertainty
2017 (English)In: Transportation Research Part E: Logistics and Transportation Review, ISSN 1366-5545, E-ISSN 1878-5794, Vol. 98, p. 1-23Article in journal (Refereed) Published
Abstract [en]

The paper formulates and analyzes a freight transport platoon coordination and departure time scheduling problem under travel time uncertainty. The expected cost minimization framework accounts for travel time cost, schedule miss penalties and fuel cost. It is shown that platooning is beneficial only when scheduled arrival times differ less than a certain threshold. Travel time uncertainty typically reduces the threshold schedule difference for platooning to be beneficial. Platooning in networks is less beneficial on converging routes than diverging routes, due to delay at the merging point. The model provides valuable insights regarding platooning benefits for freight transport planning.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Heavy-duty vehicle platooning, Freight transport, Scheduling, Travel time uncertainty
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-200536 (URN)10.1016/j.tre.2016.11.008 (DOI)000393241700001 ()2-s2.0-85006409705 (Scopus ID)
Note

QC 20170201

Available from: 2017-01-30 Created: 2017-01-30 Last updated: 2019-06-10Bibliographically approved
2. Platoon coordination with time windows: An operational perspective
Open this publication in new window or tab >>Platoon coordination with time windows: An operational perspective
2017 (English)In: 20th EURO Working Group on Transportation Meeting, EWGT 2017, 4-6 September 2017, Budapest, Hungary, Elsevier, 2017, Vol. 27, p. 357-364Conference paper, Published paper (Refereed)
Abstract [en]

It has been reported that platooning has the potential of saving fuel and increasing traffic throughput. We formulate a platoon coordination problem with soft time windows as a mixed-integer linear programming problem and solve it with exact solutions. The objective function consists of operation costs, schedule miss penalties and fuel costs. In the numerical example, a Swedish highway network model is used and the computation result shows that, for 21 vehicles, the total cost can be reduced by 3.5% when the optimal preferred arrival times are chosen. A random disturbance is then added to the optimal time windows and the optimal result shows great sensitivity with respect to the disturbance. When the mean of the disturbance becomes larger than 10 minutes, more than half of the platooning benefits will be lost. The study also analyzes the change of different cost compositions as disturbance increases.

Place, publisher, year, edition, pages
Elsevier, 2017
Series
Transportation Research Procedia, ISSN 2352-1457 ; 27
Keywords
freight transportation, Heavy-duty vehicle platooning, operational cost, time window
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-222070 (URN)10.1016/j.trpro.2017.12.129 (DOI)2-s2.0-85039950890 (Scopus ID)
Conference
20th EURO Working Group on Transportation Meeting, EWGT 2017, 4-6 September 2017, Budapest, Hungary
Note

QC 20180131

Available from: 2018-01-31 Created: 2018-01-31 Last updated: 2019-05-17Bibliographically approved
3. Efficiency of semi-autonomous and fully autonomous bus services in trunk-and-branches networks
Open this publication in new window or tab >>Efficiency of semi-autonomous and fully autonomous bus services in trunk-and-branches networks
2019 (English)In: Journal of Advanced Transportation, ISSN 0197-6729, E-ISSN 2042-3195, article id 7648735Article in journal (Refereed) Published
Abstract [en]

Automation technology is expected to change the public transport sector radically in the future. One rising issue is whether to embrace the intermediate stage of semi-autonomous buses or to wait until fully autonomous buses are available. This paper proposes a cost model of bus operations considering automation technology. The generalized cost, which is the sum of waiting, riding, operating, and capital cost, is modeled for conventional, semi-autonomous, and fully autonomous bus services on a generic trunk-and-branches network. Semi-autonomous buses achieve reduced unit operating cost through automated platooning on the corridor. The relative efficiency of the different services is studied under a range of scenarios for commercial speed, network structure, and demand distribution. Analytical and numerical results show that fully autonomous buses exhibit great potential through reduced operating and waiting costs even if the additional capital cost is high. The advantages of semi-autonomous buses are weaker and most prominent in networks with low demand along a long corridor such as interurban networks. For both automation levels a commercial speed comparable to conventional vehicles is crucial. The established criteria provide input to planners and operators for understanding the potential of automated bus services.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2019
National Category
Transport Systems and Logistics
Identifiers
urn:nbn:se:kth:diva-237286 (URN)10.1155/2019/7648735 (DOI)000460891200001 ()2-s2.0-85062792951 (Scopus ID)
Note

QC 20181107

Available from: 2018-10-26 Created: 2018-10-26 Last updated: 2019-05-24Bibliographically approved
4. Efficiency of connected semi-autonomous platooning bus services in high-demand transit corridors
Open this publication in new window or tab >>Efficiency of connected semi-autonomous platooning bus services in high-demand transit corridors
(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:nbn:se:kth:diva-251621 (URN)
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

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