We analytically study a discrete-space version of the spatial model of agglomeration proposed by Allen and Arkolakis.1) Employing the bifurcation analysis method developed by Akamatsu et al.,14) we show that the model exhibits, if any, only mono-centric or unimodal spatial concentration patterns of mobile agents. The properties we reveale in this paper pose one simple but significant issue: Can we justify fitting the model to the actual spatial patterns, which are typically not mono-centric but poly-centric? We argue that, the unobserved amenity approach, which Allen and Arkolakis and other recent studies employ to circumvent the issue, is an inappropriate one as it can replicate any observed data with any model.
In a disaster situation, people are easy to do similar behaviors of others because they don't have enough disaster-experiences to decide by just themselves. Our local interaction based model evaluate influences of others' behaviors to understand evacuation timing. The proposed model introduces a preference of inequality aversion on spatial and social network. Our model performance is demonstrated using evacuation behavior data in 2004 heavy rain disaster of Niihama city. The parameters are estimated by a pseudo maximum likelihood estimation method. Our results show that influences of others are difference depending on their relationships and social networks.
Agglomerations of population were analyzed by NEG models in new economic geography (NEG) mostly in two-place and racetrack economies. In the racetrack economy, agglomerations proceed via so-called spatial period doubling bifurcation cascade. Since this cascade exists for 2k cities, studies of agglomeration up to now have been conducted for such cities. This paper aims at the elucidation of the bifurcation and agglomeration properties of the racetrack economy with an arbitrary number of cities. A bifurcation theory of NEG models is proposed and numerical analysis of the Forslid & Ottaviano and Pflüger models is conducted. Dependence of the bifurcation and agglomeration on the models and on the number of cities is made clear.
This paper clarifies the relationship between a Macroscopic Fundamental Diagram (MFD) and congestion patterns on a general network with one-to-many OD pairs. Specifically, we formulate a new inverse problem of the dynamic user equilibrium assignment problem for a given congestion pattern. The proposed problem is formulated as a system of linear equations; by solving this, we can derive an analytical formula of a trip completion rate consistent with the congestion pattern. Through a sensitivity analysis of this formula, we identify the types of congestion patterns that cause the decreasing of a trip completion rate (the mechanism of a decreasing branch of MFDs).
In order to improve safety, platform doors have been installed in some train and subway stations in the Tokyo metropolitan area of Japan. The number of accidents (such as passengers falling from platforms, or coming into contact with moving trains) has decreased. On the other hand, scheduled dwell times have had to be increased to allow for the extra time needed for platform doors to open and close. As such, travel times are longer after the installation of platform doors than before. However, an overall improvement in the stability of train operations has been observed during rush hour. Due to the fact that some passengers walk at the edge of platforms, it is often difficult for station staff to confirm safety along the sides of train cars. This is especially true before train departures. The installation of platform doors prevents passengers from approaching the sides of cars too closely, and obstacle sensors attached to the platform doors work to confirm safety in the direct vicinity of trains in stations. In this sense, the time and labor required for station staff to make visual safety checks is alleviated by the function of platform doors. It is therefore recognized that the installation of platform doors has a net positive effect on train transportation stability. This paper presents an analysis of the effect that installation of platform doors has on train operation stability.
This paper proposes an approximation method of expected delay for signalized arterial roads under stochastic arrivals. This method is based on variational theory of traffic flow (VT). In VT under stochastic arrivals, traffic flow dynamics is described as the solution of the stochastic shortest path problem in the network on a space-time domain, which cannot be solved exactly. We, thus, propose the approximation method that consists of the following two procedures: (i) solution space reduction based on the characteristics of the shortest path; (ii) analytical evaluation of multiple integral by Clark approximation. Throughout the experimental comparison with a Monte Carlo simulation, we demonstrate that the error of the proposed method is extremely small. Finally, we show a case study of a coordinated traffic signal optimization as an application of the proposed method.
In this study, we formed a framework for the comprehensive understanding of the determinants of social acceptance. While previous studies have clarified psychological determinants, which affect acceptance on public projects, using a bottom-up approach, this study used a top-down approach for comprehensively understanding the determinants by applying the findings of the communication study. The determinants were classified into five factors from the findings: proposer, evaluator, object, process for decision, and situation. After confirming whether the factors were appropriate or not by referencing previous studies, we discussed how to utilize the framework for researchers and practitioners.
Planning systems for the realization of compact city policy have developed rapidly in recent years. Along with changes, have city planners in local governments, who used to regard realization of the policy as difficult, changed their outlook? This study clarifies their changes based on original attitudes survey, between 2007 when a compact city policy was introduced and 2015 when the law was carried out for the first time. Results show that (1) Acceptability of compact city policy has not changed. (2) Practical difficulties hindering realization of the policy have been shifted from planning systems to business affairs. (3) Difficulties related to the mode of information dissemination have become apparent, especially how to use withdrawal areas in suburbs.
This paper corrects and modifies some properties of the Iryo's (2011) solution algorithm of Nash equilibrium in dynamic traffic assignment, in which each discretized vehicle is assigned on its shortest path one-by-one in an appropriate order. Specifically, we first give a counterexample to the theorem that guarantees the algorithm produces a Nash equilibrium solution for single destination networks. This example shows that it is almost impossible to obtain the Nash equilibrium by assigning each vehicle in the order based on that theorem. We then prove the existence of an appropriate vehicle assignment order for single destination networks, which guarantees the applicability of the Iryo's algorithm to those networks.