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The Impacts of Heavy-Duty Vehicle Platoon Spacing Policy on Traffic Flow
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Spacing policy of heavy-duty vehicle (HDV) platoons determines the inter-vehicle distance between HDVs in steady state. It plays an important role in traffic throughput. For example, an HDV platoon with small spacing policies saves space on the highway so that it can accommodate more vehicles. Therefore, the traffic efficiency and highway capacity may be improved by applying small spacing policies on HDV platoons. Conversely, an HDVplatoon with larger spacing policies requires more space on highways and thus has a negative impact on capacity.This paper specifically focuses on two commonly used spacing policies in HDV platooning, constant vehicle spacing (CVS) and constant time gap (CTG) and investigates respective impacts on traffic flow. The speed-density relation of mixed traffic flow is formulated as a function of traffic density, the percentage of HDVs on highway and spacing policy of HDV platoon. In order to investigate the effects of HDV platooning to vehicle interaction, the speed-density relation is derived from car-following model. Numerical results show that HDV platooning with CVSpolicy yields the most significant improvement in highway capacity, compared with no HDV platooning scenario and HDV platooning with CTG policy. However, it has worse performance in heavily congested traffic flows thanCTG policy. A mixed CVS-CTG policy is therefore proposed in this study, in order to combine the benefits fromCVS and CTG policies to traffic flow. This mixed spacing policy could be a promising alternative to the single spacing policy.

National Category
Engineering and Technology
Research subject
Transport Science
Identifiers
URN: urn:nbn:se:kth:diva-181930OAI: oai:DiVA.org:kth-181930DiVA: diva2:901957
Note

QS 2016

Available from: 2016-02-09 Created: 2016-02-09 Last updated: 2016-02-10Bibliographically approved
In thesis
1. Heavy-Duty Vehicle Platooning: Modeling and Analysis
Open this publication in new window or tab >>Heavy-Duty Vehicle Platooning: Modeling and Analysis
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Coupled with the growth of world economy, the demand for freight transport has escalated and will continue to do so. As the traffic intensity increases, the pressure on infrastructure, energy usage and environment becomes higher than ever. Meanwhile, the number of traffic accidents is also increasing year by year as a result. Heavy-duty vehicle (HDV) platooning makes a group of HDVs driving closely after each other.It is one potential solution to improve transport efficiency, traffic safety and fuel economy. Even though there have been extensive studies on the platooning system and corresponding fuel saving, some of the research areas, such as coordination strategies of platooning, platoon operations and the impacts of HDV platooning on trafficflow are still left open. Under a futuristic scenario where a large number of HDVswill be operating in one or several platoons on highway, how to group HDVs intoa platoon and how to select spacing policies for HDV platooning are essential forautomobile manufacturers, fleet operators and transport planners. Therefore, theformation strategies and operations of HDV platoons, as well as the impacts of HDVplatooning on traffic flow have to be carefully investigated.

This thesis presents contributions to the modeling of HDV platooning and simulationof HDV platoon operations. The focus lies mainly on analytical formulation ofspeed-density relation of mixed traffic flow and development of simulation frameworkfor study of HDV platooning. On the one hand, a three-regime speed-density relationis proposed to describe the mixed traffic flow consisting of HDVs and passengercars. The proposed speed-density relation incorporates percentage of HDVs, trafficdensity and spacing policy of HDV platoons as input variables and delivers aggregatehighway velocity as output. By comparing the traffic throughput of no HDV platooningscenario, grouping HDVs into platoon using constant vehicle spacing policy orconstant time gap policy results in significant improvement in highway capacity. On the other hand, a simulation framework is developed for implementation of differentHDV platoon operations. The platoon formation of two HDVs and disaggregation ofa five-HDV platoon at off-ramp are simulated on a two-lane highway. The simulationoutcomes show that HDV platoon formation is more favorable in light and mediumtraffic; disaggregation of a long HDV platoon at off-ramp improves the averagespeed of passenger vehicles considerably at high traffic flow rate.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. xiv, 49 p.
Series
TRITA-TSC-LIC, ISSN 1653-445X ; 15:005
National Category
Engineering and Technology
Research subject
Transport Science
Identifiers
urn:nbn:se:kth:diva-181934 (URN)978-91-87353-83-3 (ISBN)
Presentation
2016-03-08, Ångloket, Teknikringen 10, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

QC 20160210

Available from: 2016-02-10 Created: 2016-02-09 Last updated: 2016-02-10Bibliographically approved

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