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on Computational Economics |
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Issue of 2013‒10‒02
nine papers chosen by |
| By: | Cats, Oded (KTH) |
| Abstract: | Transit systems exercise complex dynamics and evolve through the interaction of various agents. The analysis of transit performance requires emulating the dynamic loading of travellers and their interaction with the underlying transit system. Multi-agent simulations aim to mimic the emergence of global spontaneous order from numerous inter-dependent local decisions. This paper presents a framework for a multi-agent transit operations and assignment model which captures supply uncertainties and adaptive user decisions. An iterative day-to-day learning process consisting of a within-day dynamic network loading loop simulates the interaction between transit supply and demand. The model requires the development and integration of several modules including traffic simulation, transit operations and control, dynamic path choice model and real-time information generator. BusMezzo, a transit simulation model, is used as the platform for implementation. |
| Keywords: | Agent-based Simulation; Public Transport; Assignment; Operations |
| JEL: | R40 |
| Date: | 2013–09–27 |
| URL: | http://d.repec.org/n?u=RePEc:hhs:ctswps:2013_024&r=cmp |
| By: | Toledo, Tomer (Technion - Israel Institute of Technology); Cats , Oded (KTH); Burghout, Wilco (KTH); Koutsopoulos , Haris N. (KTH) |
| Abstract: | This paper presents a transit simulation model designed to support evaluation of operations, planning and control, especially in the context of Advanced Public Transportation Systems (APTS). Examples of potential applications include frequency determination, evaluation of real-time control strategies for schedule maintenance and assessing the effects of vehicle scheduling on the level of service. Unlike most previous efforts in this area, the simulation model is built on a platform of a mesoscopic traffic simulation model, which allows modeling of the operation dynamics of large-scale transit systems taking into account the stochasticity due to interactions with road traffic. The capabilities of Mezzo as an evaluation tool of transit operations are demonstrated with an application to a real-world high-demand bus line in the Tel Aviv metropolitan area under various scenarios. The headway distributions at two stops are compared with field observations and show good consistency between simulated and observed data. |
| Keywords: | Simulation; Public transport; Operations; ITS |
| JEL: | R40 |
| Date: | 2013–09–27 |
| URL: | http://d.repec.org/n?u=RePEc:hhs:ctswps:2013_029&r=cmp |
| By: | Ferede, Tadele; Gebreegziabher, Zenebe; Mekonnen, Alemu; Guta, Fantu; Levin, Jörgen; Köhlin, Gunnar |
| Abstract: | In this study, we assess the economy-wide effects of biofuel investment in Ethiopia, with a focus on the external sector. The Government of Ethiopia has been revising its energy policy to switch from imported fossil oil to domestically produced biofuels, partly in response to climate change and partly in response to rising world oil prices, which leave oil-importing countries such as Ethiopia vulnerable to external oil price shocks. In Ethiopia, the value of oil imports relative to export earnings has increased over time, which has negatively impacted its balance of payments. Specifically, this paper assesses the implications of biofuels investment for growth and the external sector in Ethiopia using a dynamic recursive computable general equilibrium (CGE) model. The study is based on primary data collected from biofuel firms in Ethiopia and assumes that the amount of land is fixed in a given period. The results indicate that the macroeconomic and sectoral effects of biofuel investment in the context of Ethiopia are mixed. Biofuel expansion can help to improve economic growth if such expansion generates spillover effects, with jatropha and castor bean found to have the strongest positive impact on the economy. Without spillovers, the effect of biofuel investment on economic growth is negligible, indicating the importance of technology transfers. The impact on the external sector, especially on exports and imports, is negative, as biofuels expansion affects both the real exchange rate and production of export commodities. This negative effect might be mitigated by policies encouraging biofuels investment to move in a direction that does not compete with the use of land for traditional export crops. |
| Keywords: | biofuels, CGE model, economic growth, external sector, Ethiopia |
| JEL: | O11 O2 O47 O55 Q42 |
| Date: | 2013–07–19 |
| URL: | http://d.repec.org/n?u=RePEc:rff:dpaper:dp-13-08-efd&r=cmp |
| By: | Leo Krippner |
| Abstract: | The Black framework offers a theoretically appealing way to model the term structure and gauge the stance of monetary policy when the zero lower bound of interest rates becomes constraining, but it is time consuming to apply using standard numerical methods. I outline a faster Monte Carlo simulation method for Black implementions, illustrate its performance for a one factor model, and then discuss the ready extension to models with multiple factors. |
| Keywords: | Black framework, zero lower bound; shadow short rate; term structure model |
| JEL: | E43 G12 G13 |
| Date: | 2013–09 |
| URL: | http://d.repec.org/n?u=RePEc:een:camaaa:2013-66&r=cmp |
| By: | Cats, Oded (KTH); Nabavi Larijani, Anahid (KTH); Koutsopoulos, Haris N. (KTH); Burghout, Wilco (KTH) |
| Abstract: | Transit operators are interested in strategies to improve service reliability as it is an important measure of performance and level of service. One of the common practices aimed to reduce service unreliability is holding control strategies. The design of these strategies involves the selection of a set of time point stops and the holding criteria for regulating the departure time. In order to analyze the impacts of holding strategies on transit performance, it is necessary to model dynamically the interactions between passenger activity, transit operations and traffic dynamics. An evaluation of different holding criteria and number and location of time point stops was conducted using BusMezzo, a dynamic transit simulation model. The holding strategies were implemented in the model and applied to a high frequency trunk bus line in Stockholm. The analysis of the results considers the implications of holding strategies from both passengers and operator perspectives. The analysis suggests substantial gains from implementing holding strategy based on the mean headway from the preceding bus and the succeeding bus. This strategy is the most efficient in terms of passenger time savings as well as fleet costs and crew management. |
| Keywords: | Transit Operations; Reliability; Simulation; ITS; Holding |
| JEL: | R40 |
| Date: | 2013–09–27 |
| URL: | http://d.repec.org/n?u=RePEc:hhs:ctswps:2013_027&r=cmp |
| By: | Hisahiro Naito |
| Abstract: | The effect of accepting more immigrants on welfare in the presence of a pay-as-you-go social security system is analyzed qualitatively and quantitatively. First, it is shown that if initially there exist intergenerational government transfers from the young to the old, the government can lead an economy to the (modified) golden rule level within a finite time in a Pareto-improving way by increasing the percentage of immigrants to natives (PITN). Second, using the computational overlapping generation model, the welfare gain is calculated of increasing the PITN from 15.5 percent to 25.5 percent and years needed to reach the (modified) golden rule level in a Pareto-improving way in a model economy. The simulation shows that the present value of the welfare gain of increasing the PITN comprises 23 percent of the initial GDP. It takes 112 years for the model economy to reach the golden rule level in a Pareto-improving way. |
| Date: | 2013–08 |
| URL: | http://d.repec.org/n?u=RePEc:tsu:tewpjp:2013-004&r=cmp |
| By: | Cats, Oded (KTH); Koutsopoulos, Haris N. (KTH); Burghout, Wilco (KTH); Toledo, Tomer (Technion – Israel Institute of Technology) |
| Abstract: | Real-time information is increasingly being implemented in transit networks worldwide. The evaluation of the effect of real-time information requires dynamic modeling of transit operations and of passenger path choices. This paper presents a dynamic transit analysis and evaluation tool that represents time-tables, operation strategies, real-time information, adaptive passenger choices, and traffic dynamics at the network level. Transit path choices are modeled as a sequence of boarding, walking and alighting decisions that passengers undertake when carrying out their journey. The model is applied to the Metro network of Stockholm, Sweden area under various operating conditions and information provision scenarios, as a proof of concept. An analysis of the results indicates substantial path choice shifts and potential time savings associated with more comprehensive real-time information provision and transfer coordination improvements. |
| Keywords: | Real-time information; Public transport; Route choice; Simulation |
| JEL: | R40 |
| Date: | 2013–09–27 |
| URL: | http://d.repec.org/n?u=RePEc:hhs:ctswps:2013_028&r=cmp |
| By: | Cats, Oded (KTH); Nabavi Larijani, Anahid (KTH); Ólafsdóttir, Ásdís (KTH); Burghout, Wilco (KTH); Andreasson, Ingmar (KTH); Koutsopoulos, Haris N. (KTH) |
| Abstract: | Transit operations involve several inherent sources of uncertainty including dispatching time from the origin terminal, travel time between stops and dwell time at stops. Bus holding control strategies are among the prominent methods applied by transit operators in order to improve transit performance and level of service. The common practice is to regulate departures from a limited number of stops by holding buses until the scheduled time. An analysis of the performance of a high-frequency bus line in Stockholm based on Automatic Vehicle Location (AVL) data shows that this control strategy is not effective in improving service regularity along the line. It also indicates that drivers adjust their speed based on performance objectives. Implications of a control strategy that regulates departures from all stops based on the headways from the preceding bus and the following bus were evaluated using BusMezzo, a transit operations simulation model. The results suggest that this strategy can improve service performance considerably from both passengers and operators perspectives. In addition, it implies cooperative operations as the decisions of each driver are interdependent of other drivers with mutual corrections. The difficulties in realizing the benefits of the proposed strategy in practice such as dispatching from the origin terminal, driver scheduling and compliance are discussed. The implications of several practical considerations are assessed by conducting a sensitivity analysis as part of the preparations to a field experiment designed to test the proposed control strategy. |
| Keywords: | Public transport; Operations; Simulation; Field experiment; Reliability |
| JEL: | R40 |
| Date: | 2013–09–27 |
| URL: | http://d.repec.org/n?u=RePEc:hhs:ctswps:2013_026&r=cmp |
| By: | Miguel Sánchez Romero (Max Planck Institute for Demographic Research, Rostock, Germany); Naohiro Ogawa; Rikiya Matsukura |
| Abstract: | In Japan due to the rapid population aging and its large financial pressure on pay-as-you-go retirement systems, the economic impact of bequest wealth has been drawing a tremendous amount of attention. Despite that, there are neither official statistics on bequest for the whole population, nor analyses of the historical evolution of bequest. Our study fills this gap by offering an estimate of bequest in Japan from 1850 to 2100, based on a computable general equilibrium model with realistic demography. Our model shows that the historical evolution of the bequest-to-output ratio in Japan follows the same U-shaped pattern described by Piketty (2011) for France. Moreover, we estimate that the annual flow of bequest represented between 4% and 6% of the output in the year 2000 and that it will reach between 7% and 13% of the output by year 2100. |
| Keywords: | Japan, economic demography, inheritance, mortality |
| JEL: | J1 Z0 |
| Date: | 2013–09 |
| URL: | http://d.repec.org/n?u=RePEc:dem:wpaper:wp-2013-012&r=cmp |