周三，10月19日，下午 2:30; 3号楼3楼会议室

[葛颖恩]

各位老师、同学，

这周三迎来我们的有一个SemiTranS研讨会，

地点： 3号楼3楼会议室
时间：周三，10月19日，下午 2:30
报告人：英国利兹大学运输研究所 Dr LIU Ronghui资深高级研究员
报告题目1：
On the Fundamental Diagram and Supply Curves for Congested Urban Networks (Transportation Research Part A, Vol 45 (2011), 951-965)

摘要：Macroscopic fundamental diagrams (MFD) of traffic for some networks have been shown to have similar shape to those for single links. They have erroneously been used to help estimate the level of travel in congested networks. We argue that supply curves, which track vehicles in their passage through congested networks, are needed for this purpose, and that they differ from the performance curves generated from MFD. We use a microsimulation model, DRACULA and two networks, one synthesizing the network for Cambridge, England, and one of the city of York, England, to explore the nature of performance curves and supply curves under differing patterns of demand.
We show that supply curves differ from performance curves once the onset of congestion is reached, and that the incorrect use of performance curves to estimate demand can thus seriously underestimate traffic levels, the costs of congestion, and the value of congestion relief measures. We also show that network aggregated supply curves are sensitive to the temporal distribution of demand and, potentially, to the spatial distribution of demand. The shape of the supply curve also differs between origin-destination movements within a given network.
We argue that supply curves for higher levels of demand cannot be observed in normal traffic conditions, and specify ways in which they can be determined from microsimulation and, potentially, by extrapolating observed data. We discuss the implications of these findings for conventional modeling of network management policies, and for these policies themselves.


报告题目2：
Modelling Motorway Merge: The Current Practice in the UK and Towards Establishing General Principles

摘要：Motorway merging has been regarded as a major source of conflicts and congestion on motorways, but has long been recognised as an area in which modelling has been relatively weak. The current traffic models represent the traffic operations at a merge using gap-acceptance approach, with the merging traffic giving-way to traffic on the mainline carriageway and imposing little or no delay to the mainline traffic. The results tend to underestimate the capacity of the merge, overestimate delays to the merging traffic, and underestimate delays and interruptions to the mainline traffic.
This paper investigates the current practice in modelling motorway merge in the UK and highlights some major conceptual and methodological differences to those in the US and Germany. Studies based on empirical observations and a microsimulation modelling were carried out to improve understanding of the factors involved in the performance at merge. The results demonstrate the sensitivity of model predictions – and perhaps policy decisions – to the behavioural assumptions made in traffic models. The paper provides simple, practical recommendations to improve the current practice on modelling merge by the consideration of peak flow profile in the estimation of merge capacity, realistic local and variable pcu values for heavy vehicles, and a more confined merge influence area than currently advised by COBA. It calls for further empirical and behavioural-based microsimulation analysis to inform the development of more appropriated treatment of merge in traffic models for improved predictions and better investment decisions.

欢迎大家踊跃参加。

致谢，

葛颖恩

[ctr]

葛老师：科技园已经订好。207房间，时间是6点。留的你的电话。

 

 

2011-10-18

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方芳 

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发件人： 葛颖恩

发送时间： 2011-10-17  19:25:40

收件人： semitrans-dut; 王彪; w15184016801; szsp001

抄送：

主题： [SemiTranS-DUT:23] 周三，10月19日，下午 2:30; 3号楼3楼会议室