Children at risk: a comparison of child pedestrian traffic collisions in santiago, chile and seoul, south korea

Objective: We examine and compare pedestrian-vehicle collisions and injury outcomes involving school-age children between 5 and 18 years of age in the capital cities of Santiago, Chile and Seoul, South Korea. Methods: We conduct descriptive analysis of the child pedestrian-vehicle collision (P-VC) data (904 collisions for Santiago, and 3,505 for Seoul) reported by the police between 2010 and 2011. We also statistically analyze factors associated with child P-VCs, both by incident severity and age group using three regression models: negative binomial, probit, and spatial lag models. Results: Descriptive statistics suggest that child pedestrians in Seoul have a higher risk of being involved in traffic crashes than their counterparts in Santiago. However, in Seoul a greater proportion of children are unharmed as a result of these incidents, while more child pedestrians are killed in Santiago. Younger children in Seoul suffer more injuries from P-VCs than in Santiago. The majority of P-VCs in both cities tend to occur in the afternoon and evening, at intersections in Santiago and at midblock locations in Seoul. Our model results suggest that the resident population of children is positively associated with P-VCs in both cities, and school concentrations apparently increase P-VC risk among older children in Santiago. Bus stops are associated with higher P-VCs in Seoul, while subway stations relate with higher P-VCs among older children in Santiago. Zone-level land use mix was negatively related to child P-VCs in Seoul, but not in Santiago. Arterial roads are associated with fewer P-VCs, especially for younger children in both cities. A share of collector roads is associated with increased P-VCs in Seoul, but fewer P-VCs in Santiago. Hilliness is related to fewer P-VCs in both cities. Differences in these model results for Santiago and Seoul warrant additional analysis as do the differences in results across model type (Negative Binomial versus Spatial Lag models). Conclusions: To reduce child P-VCs, this study suggests the need to assess: subway station and bus stop area conditions in Santiago and Seoul, respectively; areas with high density of schools in Santiago; areas with greater concentrations of children in both cities; and collector roads in Seoul.MIT International Science and Technology Initiatives. MIT-Chile Seed FundUniversidad Andres Bello (Project DI-533-14/R

The potential for using urban growth management for transportation system enhancements in Developing countries : the case of the Santiago, Chile Metropolitan Region

Thesis (S.M. and M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, February 2001.Includes bibliographical references (leaves 213-224).This thesis explores the potentials for using urban growth management tools to improve transportation system performance in a developing country context, focusing specifically on the case of the Santiago de Chile metropolitan area. In industrialized countries, such as the United States, recent years have seen a renewed focus on using urban growth management for achieving mobility goals. This work looks at how such tools might be deployed in a rapidly growing urban environment, characterized by evolving institutional structures, major changes in transportation demand and services, and pressing economic, social, and environmental constraints. The thesis firs begins with an overview of the national political and administrative structure in Chile - the institutional context within which growth management must function. The thesis then presents the Santiago metropolitan area, overviewing demographics, the economy, the transportation system, urban growth patterns, and the environment. Then, the range of current instruments used for growth management in Chile and Santiago are presented, along with other relevant influences such as the public finance system. The following section reviews the real estate market, focusing on the emergence of large developers and their associated "megaprojects," which play a major role in shaping the city's growth patterns and trends. Finally, the thesis concludes with major findings, recommendations for improvements to the current growth management system, and areas for future work.by Pericles Christopher Zegras.S.M.and M.C.P

Sustainable urban mobility : exploring the role of the built environment

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2005.Includes bibliographical references (p. 231-265).This dissertation examines the concept of sustainable mobility within an urban context. In essence, the research aims to answer the question, "What role does a city's built environment play, if any, in the sustainability of its mobility system?" To answer this question, I first derive an operational definition of sustainable mobility: maintaining the capability to provide non-declining accessibility in time. Providing non-declining accessibility depends on our ability to maintain net capital (natural, human-made, social) stocks, or, at least, the capability of these stocks to provide current levels of accessibility to future generations. In other words, we can think of a more sustainable mobility system as one that provides more welfare per unit of throughput, with welfare measured by accessibility and throughput measured by mobility. This is a normative framework. It can only indicate relative levels of sustainable mobility. Within a specific city, this framework can allow us to measure which parts of the city produce more sustainable mobility patterns. To employ this framework, I utilize a utility-derived accessibility measure.(cont.) The attractiveness of a utility-based accessibility metric comes from its basis in welfare economics, its ability to account for individual characteristics and preferences, and the possibility for its derivation from the random utility-based models (e.g., logit), which have a long tradition of use in transportation planning. Also, drawing from the large research base exploring the role of the built environment on transportation, I develop several models that assess the influence of the built environment on travel behavior, in particular, motor vehicle ownership and use. These models, combined, enable the exploration of sustainable mobility within a given city. I apply the framework to the city of Santiago de Chile, utilizing data from a 2001 household travel survey and a 2001 real estate cadastre, specifying a nested destination and mode choice model, and examining a subset of discretionary trips by seven different travel modes. Variations by income, gender, and modal availability are explored. I conclude with a discussion of the implications in the face of current urban growth patterns in Santiago.by Pericles Christopher Zegras.Ph.D

By Community or Design? Age-restricted Neighbourhoods, Physical Design and Baby Boomers' Local Travel Behaviour in Suburban Boston, US

This article analyses the travel behaviour, residential choices and related preferences of 55+ baby boomers in suburban Boston, USA, looking specifically at age-restricted neighbourhoods. For this highly auto-dependent group, do neighbourhood-related characteristics influence local-level recreational walk/bike and social activity trip-making? The analysis aims to discern community (for example, social network) versus physical (for example, street network) influences. Structural equation models, incorporating attitudes and residential choice, are used to control for self-selection and to account for direct and indirect effects among exogenous and endogenous variables. The analysis reveals modest neighbourhood effects. Living in age-restricted, as opposed to unrestricted, suburban neighbourhoods modestly increases the likelihood of residents being active (i.e. making at least one local recreational walk/bike trip) and the number of local social trips. Overall, the age-restricted community status has greater influence on recreational and social activity trip-making than the neighbourhood physical characteristics, although some community–neighbourhood interaction exists.New England University Transportation Center (Grant DTRS99-G-0001

A Neural-embedded Choice Model: TasteNet-MNL Modeling Taste Heterogeneity with Flexibility and Interpretability

Discrete choice models (DCMs) and neural networks (NNs) can complement each other. We propose a neural network embedded choice model - TasteNet-MNL, to improve the flexibility in modeling taste heterogeneity while keeping model interpretability. The hybrid model consists of a TasteNet module: a feed-forward neural network that learns taste parameters as flexible functions of individual characteristics; and a choice module: a multinomial logit model (MNL) with manually specified utility. TasteNet and MNL are fully integrated and jointly estimated. By embedding a neural network into a DCM, we exploit a neural network's function approximation capacity to reduce specification bias. Through special structure and parameter constraints, we incorporate expert knowledge to regularize the neural network and maintain interpretability. On synthetic data, we show that TasteNet-MNL can recover the underlying non-linear utility function, and provide predictions and interpretations as accurate as the true model; while examples of logit or random coefficient logit models with misspecified utility functions result in large parameter bias and low predictability. In the case study of Swissmetro mode choice, TasteNet-MNL outperforms benchmarking MNLs' predictability; and discovers a wider spectrum of taste variations within the population, and higher values of time on average. This study takes an initial step towards developing a framework to combine theory-based and data-driven approaches for discrete choice modeling

Calling for validation: demonstrating the use of mobile phone data to validate integrated land use transportation models

In this paper we demonstrate the use of a particular source of ICT data, Mobile phones, generated and provided by a mobile phone service provider, to help validate an integrated land use transportation (LUT) model calibrated for the Lisbon, Portugal, metropolitan area (hereafter LMA). Specifically, we use 1 month of anonymous data provided by a private cell phone network operator. These data allowed us to identify, for each phone, all phone activity, localized to the nearest cellular telephone tower (601 towers in LMA). We use the cellular phone towers to generate analysis zones consistent with existing statistical and administrative boundaries (i.e., census blocks and civil parishes). We also infer, for each cell phone tower analysis zone, the number of phones that “reside” and/or “work” in that zone, based on the phone activity profile generated over the observed month.Peer Reviewe

Fiscal federalism and prospects for metropolitan transportation authorities in Portugal

Fiscal federalism refers to the attribution of public finance functions among different levels of government. We examine Portugal's metropolitan transportation sector through the fiscal federalist lens, in light of the country's decentralization efforts and new relevant legislation. We clarify basic principles of fiscal federalism and adapt them to the finance of metropolitan transportation systems – typically characterized by multiple jurisdictions, numerous externalities and equity concerns – showing the inadequacy of general practice. Portugal's overall public finance system partially adheres to fiscal federalist principles; the transportation sector less so. Metropolitan transportation faces particular troubles, with few direct user fees, prices inadequately reflecting costs, and heavy reliance on central government subsidies for public transportation investments and operations. A new law creating metropolitan transportation authorities is only modestly consistent with fiscal federalist principles, since it inadequately details financial responsibilities and remains under heavy central government control. Absent additional reforms, the new metropolitan authorities should aim to make the transportation finance system explicit and test incentive grants to induce inter-municipal cooperation.MIT Portugal Progra

Survey Design to Unravel Freight Transportation Demand of Establishments in Cities

Freight transportation serves the vital role of fulfilling the goods demand of residents in cities, yet little is known about the mechanisms that generate freight movements and their impact on traffic. Even though technology may allow us to better trace real-time movements, establishment surveys are still important to collect data on strategic and tactical freight transportation decisions. Leveraging state-of-art knowledge, a survey was specifically designed to investigate freight travel demand. This paper shows the preparation, execution and data processing of a survey on establishments in Singapore. Analysis of the survey data allows us to explain variations in delivery, such as, the types of supplier, the size and frequency of goods deliveries, and the timing of deliveries

Stop Detection in Smartphone-based Travel Surveys

Future Mobility Sensing (FMS) is a smartphone-based travel survey system that employs a web-based prompted-recall interaction to correct automatically inferred information. A key component of FMS is a stop detection algorithm that derives the users' activity locations and times based on the raw data collected by their phones. Output of this algorithm is presented in the Activity Diary for the users to validate, and its accuracy has a significant impact on user burden. In this paper, we present FMS' stop detection algorithm and its performance during testing by volunteers and public users during a large-scale field test