Integrated models of land use and transportation for the autonomous vehicle revolution

ABSTRACT

The advent of the autonomous vehicle (AV) will affect not only the transportation system, but also future patterns of land development. Integrated land use and transportation models will be critical tools in assessing the path forward with this technology. Key questions with respect to land use impacts of AVs arise from potential changes in sensitivity to travel and reduced demand for parking. It is an open question whether AVs will induce urban sprawl, or whether spatial economies of agglomeration will mitigate any reductions in travel time sensitivity. The deployment of shared fleets of AVs would likely reduce parking demand, producing yet to be explored impacts on property development within existing urban footprints. We perform a critical assessment of currently operational models and their ability to represent the adoption of AVs. We identify the representation of time in such models as a vital component requiring additional development to model this new technology. Existing model applications have focused on the discrete addition of new infrastructure or policy at a fixed point in time, whereas AV adoption will occur incrementally through time. Stated adaptation surveys are recommended as tools to quantify preferences and develop relevant model inputs. It is argued that existing models that assume comparatively static equilibrium have been convenient in the past, but are insufficient to model technology adoption. In contrast, dynamic model frameworks lack sufficient structure to maintain reasonability under large perturbations from base conditions. The ongoing advancement of computing has allowed models to move away from being mechanistic aggregate tools, towards behaviourally rich depictions of individual persons and firms. However, much work remains to move from projections of existing conditions into the future, to the evolution of the spatial economy as it evolves through time in response to new technologies and exogenous stresses. Principles from complex and evolutionary systems theory will be important in the development of models with the capacity to consider such dynamics.     

S^2 BHCA Multiple AUVs cooperation oriented control architecture

Oceanographic survey, or other similar applications should be the applications of multiple AUVs. In this paper, the skill ＆ simulation based hybrid control architecture （S^2BHCA） as the controller＇s design reference was proposed. It is a multi-robot cooperation oriented intelligent control architecture based on hybrid ideas. The S^2BHCA attempts to incorporate the virtues of the reactive controller and of the deliberative controller by introducing the concept of the ＂skill＂. The additional online task simulation ability for cooperation is supported, too. As an application, a multiple AUV control system was developed with three ＂skills＂ for the MCM mission including two different cooperative tasks. The simulation and the sea trials show that simple task expression, fast reaction and better cooperation support can be achieved by realizing the AUV controller based on the S^2BHCA.     

Growth of urban transportation: Peoples republic of China

The Peoples Republic of China, with its great urban populations, is finding it necessary to develop a range of strategies to deal with increasing demand for goods and people movement, increasing motorization and the increasing congestion that results from the increasing travel demand. This paper discusses strategies being adopted in two northern cities, Changchun and Shenyang. Both transit and roadway programs are examined for Changchun. Problems and successes of a new toll road are examined for Shenyang. Sustained infrastructure investment is essential to assure the necessary mobility for economic growth.     

A stated preference examination of time of travel choice for a recreational trip: An addendum

A paper was published in the immediately previous issue of this journal describing a stated preference experiment examining how people are influenced in the selection of a departure time for a hypothetical trip to see a movie. The title was ‘A stated preference examination of time of travel choice for a recreational trip’, Volume 30(3):17–44. Numbers were used to indicate references in the text of the paper and in Table 1 accompanying the text, but these numbers were omitted from the list of references at the end of the paper - making it very difficult to identify specific citations. The list of references from the paper is reprinted below with the reference numbers included. This provides a listing that can be used in conjunction with the text of the paper and Table 1 as published to identify specific citations as intended.     

A second order volume of fluid （VOF） scheme for numerical simulation of 2-D breaking waves

Among all environmental forces acting on ocean structures and marine vessels, those resulting from wave impacts are likely to yield the highest loads. Being highly nonlinear, transient and complex, a theoretical analysis of their impact would be impossible without numerical simulations. In this paper, a pressure-split two-stage numerical algorithm is proposed based on Volume Of Fluid (VOF) methodology. The algorithm is characterized by introduction of two pressures at each half and full cycle time step, and thus it is a second-order accurate algorithm in time. A simplified second-order Godunov-type solver is used for the continuity equations. The method is applied to simulation of breaking waves in a 2-D water tank, and a qualitative comparison with experimental photo observations is made. Quite consistent results are observed between simulations and experiments. Commercially available software and Boundary Integral Method (BIM) have also been used to simulate the same problem. The results from present code and BIM are in good agreement with respect to breaking location and timing, while the results obtained from the commercial software which is only first-order accurate in time has clearly showed a temporal and spatial lag, verifying the need to use a higher order numerical scheme.     

Experimental study on the width of the turbulent area around bridge pier

At present, the method of calculating the turbulent flow width around the bridge pier is not given in the "Standard for Inland River Navigation" (GB50139-2004) in China, and the bridge designer usually increases the bridge span in order to ensure the navigation safety, which increases both of the structural design difficulty and the project investments. Therefore, it is extremely essential to give a research on the turbulent flow width around the bridge pier. Through the experiments of the fixed bed and the mobile bed, the factors influencing the turbulent flow width around the bridge pier have been analyzed, such as the approaching flow speed, the water depth, the angles between the bridge pier and the flow direction, the sizes of bridge pier, the shapes of the bridge pier, and the scouring around the bridge pier, etc. Through applying the dimension analytic method to the measured data, the formula of calculating the turbulent flow width around the bridge pier is then inferred.     

Mixed analysis of shell and solid elements using the overlaying mesh method

 This article presents a mixed method of analyzing shell elements and solid elements using the overlaying mesh method. In the structural design of a ship's hull, the shell elements are used for the global model. However, the solid elements are necessary to analyze the stress concentration zones or the vicinity of a crack. In such cases, the models are analyzed using zooming analysis, in which the results of a global model analysis are transferred to a local model analysis by imposing boundary conditions. This method is more advantageous than zooming analysis in terms of the accuracy of the solution and the modeling flexibility. Some examples of a plate model with a cracked surface or with a projection are shown in order to demonstrate the effectiveness of the method. Received: August 6, 2002 / Accepted: November 25, 2002 Address correspondence to: S. Nakasumi (sumi@nasl.t.u-tokyo.ac.jp) Updated from the Japanese original, which won the 2002 SNAJ prize (J Soc Nav Archit Jpn 2001;189:219–224; and 190:655–662)     

Basic Analytical Study of Pantograph-catenary System Dynamics

For a high speed electrical rail system, good dynamic performance of the pantograph-catenary system is vital for smooth and continuous current collection. It has been known for many years that to achieve this the head of the pantograph should be made as light as possible and the average stiffness of the catenary should be high. These conclusions, however, have been reached by numerical modelling and operational experience. In this paper the pantograph-catenary system is modelled as a time-varying, single degree-of-freedom system to facilitate an analytical investigation of the system dynamics. Although the model is very simple, it allows physical insight into the dynamic behaviour of the system, and because the excitation is parametric it also allows the stability of the system to be investigated. The finite element method is used to determine the catenary characteristics and Floquet theory is used to analyse the behaviour of the coupled system.     

Dynamic Simulation of a Smart Crank and Slider Mechanism

In this paper, a smart crank and slider mechanism is analyzed mostly from a dynamic view. By means of dynamic explicit finite element method, 3D nonlinear structure is simulated. It is proved that the mechanism can effectively accomplish smart movement prescribed. And in order to ensure reciprocal movement with higher frequency, measures should be taken to avoid over heating of parts. Compared with internal energy, kinetic energy of total rigid body is dominating, and Y direction equivalent rigid velocity is much higher than X direction velocity. Equivalent rigid velocity of all parts is consistent with respective movement condition. For both energy and velocity, slider effect is dominating. Three direction equivalent inertia force oscillates. Force amplitude in Y -direction is comparitively the greatest.