Simeon C. Calvert  Henk Taale  Serge P. Hoogendoorn 《先进运输杂志》2016,50(4):570-588

Many road authorities work with static values for road capacities, while it has been proven that capacity is not a fixed quantity. At the same time, there is an increasing need for accurate stochastic input for traffic models, such as the variation in road capacity. In this paper, a methodological framework with a conceptual model for practical stochastic capacity estimation is presented, and a quantification of motorway capacity variation is given for the influence of day‐type specific variations in capacity values. The results of the analysis show that there is a reduction in motorway breakdown capacity of 4% on weekend days in comparison with workdays. Furthermore, a capacity decrease of 8% was found for the discharge capacity in comparison with workdays. The analysis further shows that the breakdown capacity on holidays is not significantly lower than on workdays. Discharge capacity and capacity drops are also derived in each case. The results show that the capacity is significantly different depending on the type of day. A quantification of these differences is given in the form of a Weibull capacity estimation fit for each type‐of‐day scenario. Further consideration of the implications and applications of the framework is also given. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

    

R. S. Sharp  P. Gruber  E. Fina 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(4):510-525

ABSTRACT

Some general observations relating to tyre shear forces and road surfaces are followed by more specific considerations from circuit racing. The discussion then focuses on the mechanics of rubber friction. The classical experiments of Grosch are outlined and the interpretations that can be put on them are discussed. The interpretations involve rubber viscoelasticity, so that the vibration properties of rubber need to be considered. Adhesion and deformation mechanisms for energy dissipation at the interface between rubber and road and in the rubber itself are highlighted. The enquiry is concentrated on energy loss by deformation or hysteresis subsequently. Persson's deformation theory is outlined and the material properties necessary to apply the theory to Grosch's experiments are discussed. Predictions of the friction coefficient relating to one particular rubber compound and a rough surface are made using the theory and these are compared with the appropriate results from Grosch. Predictions from Persson's theory of the influence of nominal contact pressure on the friction coefficient are also examined. The extent of the agreement between theory and experiment is discussed. It is concluded that there is value in the theory but that it is far from complete. There is considerable scope for further research on the mechanics of rubber friction.  相似文献   

    

G. Shi  P. Dong  H. Q. Sun  Y. Liu  Y. J. Cheng  X. Y. Xu 《International Journal of Automotive Technology》2017,18(1):179-194

This paper focuses on the way of keeping shift quality of automatic transmissions consistent in mass production and with mileage accumulation. We investigate the main factors influencing the consistency of shift quality. Test results show that the torque to pressure (T2P) and pressure to current (P2I) characteristics of shifting elements are easily affected. A simulation model of an 8-speed automatic transmission is established to simulate the dynamic process of clutch-to-clutch shift. Simulation results demonstrate that the change of T2P and P2I characteristics has a significant influence on shift quality. In order to compensate for the influences, we develop two adaptive control strategies, i.e., the adaptive control strategies for torque phase and inertia phase. They make use of the measured speed information and time information to evaluate shift quality. Then the control parameters are tuned to adapt to the change of T2P and P2I characteristics. Vehicle tests verify that the developed adaptive control strategies are effective to keep shift quality consistent in mass production and with mileage accumulation.  相似文献   

    

Y. Z. Tao  Y. Q. Jiang  J. Du  S. C. Wong  P. Zhang  Y. H. Xia  K. Choi 《先进运输杂志》2014,48(7):782-797

This paper presents a continuum dynamic traffic assignment model for a city in which the total cost of the traffic system is minimized: the travelers in the system are organized to choose the route to their destinations that minimizes the total cost of the system. Combined with the objective function, which defines the total cost and constraints such as certain physical and boundary conditions, a continuum model can be formulated as an optimization scheme with a feasible region in the function space. To obtain an admissible locally optimal solution to this problem, we first reformulate the optimization in discrete form and then introduce a heuristic method to solve it. This method converges rapidly with attractive computational cost. Numerical examples are used to demonstrate the effectiveness of the method. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

    

Mesut Kumru  Pınar Yıldız Kumru 《先进运输杂志》2014,48(8):974-999

As a multi‐criteria decision‐making (MCDM) method, the analytic hierarchy process (AHP) has been used considerably to solve hierarchical or network‐based decision problems in socio‐economic fields. Following an in‐depth explanation of the transport function in logistics and an overview of the MCDM methods, the AHP model is employed in the paper for a logistics company in selecting the most suitable way of transportation between two given locations in Turkey. The criteria used in the selection of transportation modes are identified as the cost, speed, safety, accessibility, reliability, environmental friendliness, and flexibility. Several cost parameters (transportation, storage, handling, bosphorus crossover) are incorporated into the decision‐making process. The application is carried out in instructional character. The results of the study indicate that the railway transportation, which is not widely used in Turkey, is also an alternative and suitable means of transportation. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

    

Becky P. Y. Loo  Dennis Y. N. Li 《Transportation》2006,33(2):115-132

Rapid urbanization has taken place in China since the Open Policy in 1978. In face of the growing demand for mobility in large cities, new metro systems were developed in large cities like Guangzhou and Shanghai. At present, there are seven cities with 10 metro lines under construction. What are the policy issues and major challenges of developing metro systems in China? This paper systematically reviews the current situation and highlights three major gaps that Chinese cities have to overcome in planning metro systems. They are the technology gap, the financing gap and the affordability gap. A discussion of these gaps in the Chinese context leads us to the conclusion that early planning and careful studies are important in the development of metro systems in China. Moreover, the existing official criteria (population and economic power) for approving the building of metro systems are insufficient and should be supplemented by more vigorous evaluation criteria.  相似文献   

  总被引：1，自引：0，他引：1  

Adam J. Pel  Michiel C. J. Bliemer  Serge P. Hoogendoorn 《Transportation》2012,39(1):97-123

Dynamic traffic simulation models are frequently used to support decisions when planning an evacuation. This contribution reviews the different (mathematical) model formulations underlying these traffic simulation models used in evacuation studies and the behavioural assumptions that are made. The appropriateness of these behavioural assumptions is elaborated on in light of the current consensus on evacuation travel behaviour, based on the view from the social sciences as well as empirical studies on evacuation behaviour. The focus lies on how travellers’ decisions are predicted through simulation regarding the choice to evacuate, departure time choice, destination choice, and route choice. For the evacuation participation and departure time choice we argue in favour of the simultaneous approach to dynamic evacuation demand prediction using the repeated binary logit model. For the destination choice we show how further research is needed to generalize the current preliminary findings on the location-type specific destination choice models. For the evacuation route choice we argue in favour of hybrid route choice models that enable both following instructed routes and en-route switches. Within each of these discussions, we point at current limitations and make corresponding suggestions on promising future research directions.  相似文献   

    

K. M. Gwilliam  C. A. Nash  P. J. Mackie 《运输评论》2013,33(3):215-222

In our critique for the Buses White Paper, we argued that ‘competition for licences’ could achieve most of the benefits of competition without the major disadvantages of ‘competition on the road’. In response to the comments of Beesley and Glaister, we explain how comprehensive franchising of good and bad routes alike would encourage effective competition, whilst providing conditions for the transparent continuation of cross‐subsidy where that was the choice of the local authority in question. We correct their misrepresentation of our arguments on the desirability of cross‐subsidy and on the case for minibuses, and explain why we believe that such cost savings as are achieved will be mainly at the expense of staff or customer service. Finally, we restate the case for believing that a unified planned timetable will provide a better service for a given level of resources than will uncoordinated competitive services.  相似文献   

    

P. G. Patankar 《运输评论》2013,33(3):287-288

Bombay, the commercial capital of India, is suffering from traffic thrombosis. Bombay used to be an attractive city some three decades ago and was commonly referred to as ‘Bombay the Beautiful’. The picture is now, however, the opposite extreme.

The way Bombay has grown, an underground railway is no doubt justified. Unfortunately, the economy may not be able to afford it for many years to come. Low cost measures have therefore to be adopted like (a) development of land use with a view to controlling the traffic demand itself; (b) discouraging further growth in and around the existing congested central business district; (c) establishment of a counter‐magnet; (d) conversion of the mono‐centric pattern to a poly‐nucleated structure; (e) better pedestrian facilities; (f) intermediate public transport; (g) traffic management measures to maximize available road capacities; (h) bus priority measures; (i) creating an east‐west axis for activities to relieve the present north‐south axis.

This would form the core of transport strategy. Capital intensive rail projects will face severe shortage of funds. An additional road/rail link has also been suggested to the mainland. The congestion in Bombay can be relieved if the master plan is prepared for an integrated system. Traffic and town planning must go hand in hand with priority to traffic planning.  相似文献   

    

Becky P. Y. Loo  W. T. Hung  Hong K. Lo  S. C. Wong 《运输评论》2013,33(5):613-639

Abstract

This paper proposes a nine‐component analytical framework for developing, comparing, and evaluating road safety strategies. The nine components are: (1) vision; (2) objectives; (3) targets; (4) action plan; (5) evaluation and monitoring; (6) research and development; (7) quantitative modelling; (8) institutional framework; and (9) funding. While the first four components are essential for the formulation of a road safety strategy, the remaining components are key to its successful implementation. To demonstrate the usefulness of this comparative framework, we examine the road safety strategies of six selected administrations: Australia, California, Great Britain, Japan, New Zealand, and Sweden. In these case studies, we extract and highlight good practices in the formulation and implementation of their road safety strategies. The proposed framework also provides a systematic approach for assessing road safety strategies in other administrations. The evaluation of the six case studies forms a benchmarking platform for the planning, formulation, and implementation of good practices for road safety strategies.  相似文献