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- ItemThe impact of using a naive approach in the limited-stop bus service design problem(Pergamon, Elsevier Science Ltd, 2021) Kumar Suman, Hemant; Larraín Izquierdo, Homero; Muñoz Abogabir, Juan Carlos; CEDEUS (Chile)The proven benefits of limited-stop services have captured the attention of researchers, especially during the last decade. However, to solve the limited-stop service design problem many existing works directly impose a capacity constraint to a total social cost objective function. This "naive approach" implicitly assumes that passengers behave altruistically, basing their decisions on what is best for the whole system. Although this issue has been identified in earlier works, the magnitude of the error induced by this simplification has not been studied yet. The objective of this work is to measure this error and to understand how it misrepresents passenger flows and bus occupation rates. To measure this error gap, we optimize a set of test scenarios by applying a naive approach, and then take the resulting design and obtain a benchmark passenger assignment using a simple behavioral model. We propose two main indicators to compare both passenger assignment: the total passenger deviation, and the total capacity deficit. This comparison reveals that the assignment of the naive approach may indeed be unrealistic, and raises concerns that a network design based on the naive approach might have severe problems when implemented. Thus, the work highlights the importance of taking the results of the naive approach with caution and verify them with a passenger assignment model before their implementation.
- ItemComparing social costs of public transport networks structured around an Open and Closed BRT corridor in medium sized cities(2020) Proboste Cárdenas,Francisco Javier; Muñoz Abogabir, Juan Carlos; Gschwender Krause, Antonio Enrique; CEDEUS (Chile)Bus Rapid Transit (BRT) has proven to be an effective and affordable transportation option for large-sized cities. In these cities, BRT is usually considered an effective complement or substitute for rail-based systems, playing a key role in complex multimodal networks with several massive transport corridors. More recently, medium-sized cities of less than 200,000 inhabitants have also considering implementing BRT as a means of mass transit. These cities usually need only a few of these massive transport corridors (often just one), and they must decide how to structure their services. This report discusses which of the two types of BRT-based networks is best for the social interest in the case of medium-sized cities: (1) Closed BRT, in which buses operating inside and outside the corridor are separated and have different designs, or (2) Open BRT, in which the same buses operate inside and outside the corridor, entering and exiting at different points along a route. To answer this question two models with different levels of detail in terms of a city's characteristics were developed to represent both agency and user costs. In the first model a classic idealized city approach is addressed, while in the second model the problem is solved for the specific geographic characteristics and constraints of a real city. The results based on both models show that when it is optimally configured, Closed BRT networks offer mid-sized cities higher frequencies and lower waiting times. However, these benefits do not offset the cost associated with higher number of transfers that Closed BRT networks require, as compared to Open BRT networks. Transfers not only affect users due to the transferring experience, but also end up making the entire system slower. Overall, Open BRT shows significantly less Total Costs than Closed BRT in most of the scenarios that were analyzed.
- ItemLocalising urban sustainability indicators: the CEDEUS indicator set, and lessons from an expert-driven process(Elsevier Ltd., 2020) Steiniger, Stefan; Wagemann, Elizabeth; Barrera Melgarejo, Francisco Javier de la; Molinos Senante, María; Villegas Salgado, Rodrigo Andrés; Fuente, Helen de la; Vives Vergara, Alejandra; Arce, Guillermo; Herrera Maldonado, Juan Carlos; Carrasco Montagna, Juan Antonio; Pasten González, Pablo Arturo; Muñoz Abogabir, Juan Carlos; Barton, Jonathan Richard; CEDEUS (Chile)The development and application of urban sustainability indicators has gained momentum in recent years, especially since the generation of specific urban indicators for the Agenda 2030. Urban sustainability is a broad concept involving many dimensions, therefore the generation of a short, but comprehensive list of indicators is a significant challenge. In this paper, we present a set of 29 indicators designed to characterise urban sustainability in Chile, which we also expect to be relevant to other cities, particularly in the Global South where issues of poverty and inequality are prevalent. We first outline the process of selecting the indicators through expert consultation. Then we present selected indicators, and the variables used to measure them. Subsequently the set is applied to six Chilean cities that are diverse in terms of population, socio-economic conditions and geography. We show that some indicators highlight negative nationwide trends that are common to the cities, while other indicators reveal notable differences that can be traced back to their local contexts. The CEDEUS indicators provide a complement to the UN's Sustainable Development Goals (SDGs) for cities; therefore, a comparison is made with the SDGs. The indicator development process is critically examined and policy recommendations are given.
- ItemBuilding a geographic data repository for urban research with free software - Learning from Observatorio.Cedeus.cl(2017) Steiniger, Stefan; De La Fuente, H.; Fuentes, C.; Barton Jonathan Richard; Muñoz Abogabir, Juan Carlos; CEDEUS (Chile)The recent trend towards open data and open science as well as a demand for holistic and interdisciplinary research requires platforms that allow the distribution and exchange of research data, including geographic information. While the requirements and benefits of data exchange are widely discussed, there are few proposals on how to implement data platforms that not only permit the exchange of research data among researchers, but also permit to distribute research results and data to the interest public. We elaborate what points are important for implementing a (geographic) data repository and propose then to adopt the concept of Spatial Data Infrastructures (SDI) as a solution for the implementation of research data repositories. We present as a case study the geographic data and document repository of the Chilean research Centre on Sustainable Urban Development (CEDEUS), the CEDEUS Observatory. Besides the infrastructure to host and distribute data, communication tools are an important component of such a data repository service. For this case study we analyse which things have worked well and which things have not worked well based on the experiences collected during three years of operation. We close with some recommendations for the implementation of data repositories for research.
- ItemDesigning the incineration process for improving the cementitious performance of sewage sludge ash in Portland and blended cement systems(2019) Oliva Fonseca, Maria Renee; Vargas Muñoz, Felipe Andres; Lopez Casanova, Mauricio Alejandro; CEDEUS (Chile)["Currently, there is little doubt that the global temperature increase is a consequence of the concentrations of manmade greenhouse gases. Sustainable alternatives such as the use of supplementary cementitious materials and the reduction of sanitary landfills through the incineration of sewage sludge hold promise for the reduction of these gases.", "An experimental design is proposed to make the incineration of sewage sludge (SS) more efficient, thereby improving the sewage slush ash (SSA) produced as a supplementary cementitious material. Different maximum temperatures and residence times were studied in the partial replacement of Portland and blended cements; the resulting SSAs contributed to the mechanical behavior of concrete through improved hydraulic and pozzolanic activity in addition to intense interactions with cement.", "The particle size distributions of the SSAs were similar to those of the cements, but the specific surface areas of the SSAs were up to 18 times higher than those of the cements. This vast difference is explained by the presence of micropores after the incineration process. Consequently, the specific surface area of the SSA particles was the most important property explaining the pozzolanic activity and interaction effects with cement. Lower incineration temperatures and higher incineration times increased the specific surface area, therefore increasing the cementitious performance of SSA. The SSA cementitious performance was lower in blended cement than in Portland cement; however, the replacement of blended cement by SSA increased the compressive strength at early and late ages. (C) 2019 Elsevier Ltd. All rights reserved."]