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- Duan, Yuzhou, et al.
(författare)
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Optimising total entry delay at roundabouts with unbalanced flow: A dynamic strategy for smart metering
- 2019
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Ingår i: IET Intelligent Transport Systems. - : Institution of Engineering and Technology (IET). - 1751-9578 .- 1751-956X. ; 13:3, s. 485-494
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Tidskriftsartikel (refereegranskat)abstract
- Modern roundabouts are widely used at intersections with light traffic, generally providing safety and other advantages. However, large entry delays are often observed at roundabouts with unbalanced flow patterns, even though the entry traffic flow is not high. A metering signal-based strategy is examined to mitigate the above problems. A mathematical optimisation model is formulated firstly with the objective of minimising the total entry delay, subject to the metering signal thresholds. Then a solution algorithm based on VISSIM simulation is developed. Finally, a case study is carried out to testify the feasibility and applicability of the proposed model. Extended scenarios analyses under different levels of approach volume, different demand combinations and different proportions of right-turn vehicles (left-side driving) are also conducted. Results show that the methodology can effectively improve the operational performance, and a delay reduction of up to 25.7% can.
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| 2. |
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| 3. |
- Pajecki, Robert, et al.
(författare)
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Estimating passenger car equivalent of heavy vehicles at roundabout entry using micro-traffic simulation
- 2019
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Ingår i: Frontiers in Built Environment. - : Frontiers Media SA. - 2297-3362. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Passenger Car Equivalent (PCE) is a unit used to represent the impact of a large vehicle on a road by expressing it as the number of equivalent passenger vehicles. This paper focuses on estimating the PCE of various sized heavy vehicles in roundabouts with respect to different entry flow rates. A single-lane roundabout was tested under predefined mixed traffic and demand scenarios in VISSIM micro-simulation environments. The individual and group behavior of four separate heavy-vehicle types were tested: single-unit trucks, buses, small semitrailers, and large semitrailers. The obtained PCE values were found to be on average lower than those suggested in the United States guidelines for roundabouts. The estimated PCE values for heavy vehicles in mixed traffic conditions are 1.30 for single unit trucks, 1.40 for small semitrailers, 1.60 for buses, and 1.70 for large semitrailers. Additional factors such as varying inflow (balanced, unbalanced, and congested traffic) show direct influences on the PCE values. The PCE value under these conditions ranged from 1.25 to 1.75 for smaller vehicles (single-unit trucks, buses, and small semitrailers) and 1.45–2.10 for larger heavy vehicles (large semitrailers). A general equation was developed based on the data to relate vehicle proportions and heavy-vehicle reduction factors that would be useful for professionals to analyze the operational performance of roundabouts with better accuracy.
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| 4. |
- Pilanavithana, Udila, et al.
(författare)
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Freeway work zone: Current trends and future needs
- 2019
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Ingår i: 12th International Transportation Specialty Conference 2018, Held as Part of the Canadian Society for Civil Engineering Annual Conference 2018. ; , s. 84-93
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Konferensbidrag (refereegranskat)abstract
- Work zones are recognized as a significant source of freeway incidents as they involve frequent lane closures and lane merges that last for different periods of time. Work zones generate road user delays, traffic incidents, safety hazards, and vehicle emissions. This article presents a comprehensive literature review of the mobility, safety, driver behaviour, and cost and planning aspects of state of the art work zones. Over 100 publications, including research papers, master thesis, and dissertations were reviewed in order to understand the spread of work zone applications. Mobility and safety have become important measures that are used to optimize the performance of work zones by minimizing delay and traffic collisions. Work zone configuration plays a major role in all aspects of work zones while capacity reduction and speed limits are critical issues for mobility. The review revealed that safety is mostly modeled and predicted using collision data as the main factor. The impact of nighttime safety attracted less research attention. Cutting-edge smart work zone concepts have emerged as a key component in most of the phases of work zone studies. Driver behaviour is explored as one of the main considerations that affects the entire work zone aspects. In this article, the important elements of each publication are tabulated to give the reader quick access to the relevant references. Apart from the existing approaches, the design variables, limitations, and future research needs are listed separately for prospective users. It is our hope that this paper will serve as a quick freeway work zone reference and a guide for potential researchers and practitioners.
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| 5. |
- Wang, Shuli, 1996, et al.
(författare)
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Geographically weighted machine learning for modeling spatial heterogeneity in traffic crash frequency and determinants in US
- 2024
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Ingår i: Accident Analysis and Prevention. - 0001-4575. ; 199
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Tidskriftsartikel (refereegranskat)abstract
- Spatial analyses of traffic crashes have drawn much interest due to the nature of the spatial dependence and spatial heterogeneity in the crash data. This study makes the best of Geographically Weighted Random Forest (GW-RF) model to explore the local associations between crash frequency and various influencing factors in the US, including road network attributes, socio-economic characteristics, and land use factors collected from multiple data sources. Special emphasis is put on modeling the spatial heterogeneity in the effects of a factor on crash frequency in different geographical areas in a data-driven way. The GW-RF model outperforms global models (e.g. Random Forest) and conventional geographically weighted regression, demonstrating superior predictive accuracy and elucidating spatial variations. The GW-RF model reveals spatial distinctions in the effects of certain factors on crash frequency. For example, the importance of intersection density varies significantly across regions, with high significance in the southern and northeastern areas. Low-grade road density emerges as influential in specific cities. The findings highlight the significance of different factors in influencing crash frequency across zones. Road network factors, particularly intersection density, exhibit high importance universally, while socioeconomic variables demonstrate moderate effects. Interestingly, land use variables show relatively lower importance. The outcomes could help to allocate resources and implement tailored interventions to reduce the likelihood of crashes.
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| 6. |
- Xu, Zhigang, et al.
(författare)
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Modeling Relationship between Truck Fuel Consumption and Driving Behavior Using Data from Internet of Vehicles
- 2018
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Ingår i: Computer-Aided Civil and Infrastructure Engineering. - : Wiley. - 1093-9687 .- 1467-8667. ; 33:3, s. 209-219
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Tidskriftsartikel (refereegranskat)abstract
- In this research, by taking advantage of dynamic fuel consumption–speed data from Internet of Vehicles, we develop two novel computational approaches to more accurately estimate truck fuel consumption. The first approach is on the basis of a novel index, named energy consumption index, which is to explicitly reflect the dynamic relationship between truck fuel consumption and truck drivers’ driving behaviors obtained from Internet of Vehicles. The second approach is based on a Generalized Regression Neural Network model to implicitly establish the same relationship. We further compare the two proposed models with three well-recognized existing models: vehicle specific power (VSP) model, Virginia Tech microscopic (VT-Micro) model, and Comprehensive Modal Emission Model (CMEM). According to our validations at both microscopic and macroscopic levels, the two proposed models have stronger performed in predicting fuel consumption in new routes. The models can be used to design more energy-efficient driving behaviors in the soon-to-come era of connected and automated vehicles.
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| 7. |
- Zhu, Jie, 1990, et al.
(författare)
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Merging control strategies of connected and autonomous vehicles at freeway on-ramps: a comprehensive review
- 2022
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Ingår i: Journal of Intelligent and Connected Vehicles. - 2399-9802. ; 5:2, s. 99-111
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Forskningsöversikt (refereegranskat)abstract
- Purpose – On-ramp merging areas are typical bottlenecks in the freeway network since merging on-ramp vehicles may cause intensive disturbances on the mainline traffic flow and lead to various negative impacts on traffic efficiency and safety. The connected and autonomous vehicles (CAVs), with their capabilities of real-time communication and precise motion control, hold a great potential to facilitate ramp merging operation through enhanced coordination strategies. This paper aims to present a comprehensive review of the existing ramp merging strategies leveraging CAVs, focusing on the latest trends and developments in the research field. Design/methodology/approach – The review comprehensively covers 44 papers recently published in leading transportation journals. Based on the application context, control strategies are categorized into three categories: merging into sing-lane freeways with total CAVs, merging into singlane freeways with mixed traffic flows and merging into multilane freeways. Findings – Relevant literature is reviewed regarding the required technologies, control decision level, applied methods and impacts on traffic performance. More importantly, the authors identify the existing research gaps and provide insightful discussions on the potential and promising directions for future research based on the review, which facilitates further advancement in this research topic. Originality/value – Many strategies based on the communication and automation capabilities of CAVs have been developed over the past decades, devoted to facilitating the merging/lane-changing maneuvers at freeway on-ramps. Despite the significant progress made, an up-to-date review covering these latest developments is missing to the authors’ best knowledge. This paper conducts a thorough review of the cooperation/ coordination strategies that facilitate freeway on-ramp merging using CAVs, focusing on the latest developments in this field. Based on the review, the authors identify the existing research gaps in CAV ramp merging and discuss the potential and promising future research directions to address the gaps.
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