Urban Planning, Low-Carbon Transportation, and Health
An interdisciplinary household survey in the city of Chengdu, led by Chris NIELSEN (Harvard-China Project), James HAMMITT (Harvard T.H. Chan School of Public Health), and SHEN Mingming and YAN Jie (School of Government, Peking University), was completed in July 2016. The data have been joined with an earlier dataset collected in a nearly identical Harvard-China Project-PKU survey in 2005, to cover changes in Chengdu's economy, urbanization, travel behavior, land use, air quality, and environmental health over 11 years. In addition to this multi-faceted research on Chengdu, the Project conducts additional individual studies of transportation, land use, emissions, air quality, and/or health at urban scale.
Both the 2005 and 2016 Chengdu surveys collected data across a wide range of research interests, including transportation planning, travel behavior, mobile-source emissions, outdoor and indoor air pollution exposures, health effects of air pollution, and perceptions and valuation of health risk. Harvard researchers devised the questionnaires and are leading a number of parallel analyses. Covering 2000 households, field implementation of both surveys was led by political scientist Shen, using RCCC's rigorous geospatial sampling methods to insure inclusion of non-registered migrants left out of most social surveys in China.
Joining Hammitt and Nielsen in ongoing analyses of the datasets are China Project research affiliates GUAN ChengHe (Graduate School of Design, Harvard), Sumeeta SRINIVASAN (Department of Urban and Environmental Policy and Planning, Tufts University), WANG Haikun (School of Environment, Nanjing University), and GENG Fangli (Harvard T.H. Chan School of Public Health).
Post-colonial India has experienced rapid urbanization characterized by rural-urban migration and the prosperity of informal settlement in cities. However, urban planning and infrastructure development has paid little attention to the needs of walking accessibility for pedestrians, especially the urban poor and migrants. The goals of “Smart city”-oriented urban policy cover inclusiveness, accessibility, transparency, comfortable, safety, sustainable, etc. In order to find how such emerging policy intervention could help pedestrians, we illustrate non-motorized accessibility challenges and opportunities for migrants and urban poor in Patna and Mumbai through case studies at multiple scales and various aspects. We found that to fulfill the needs of pedestrians not only means providing them adequate facilities but also means embodying the idea of inclusiveness and users’ perceptions into practical methods for enhancing accessibility. Moreover, informality makes the vision of smart cities more complex in the two cities, which implies the significance to hearing the diverse grassroots opinions by applying “smart” governance concept as well as innovative technologies for collecting data of accessibility of different social groups.
In this paper, we discuss walkable cities from the perspective of urban planning and design in the era of digitalization and urban big data. We start with a brief review on historical walkable cities schemes; followed by a deliberation on what a walkable city is and what the spatial elements of a walkable city are; and a discussion on the emerging themes and empirical methods to measure the spatial and urban design features of a walkable city. The first part of this paper looks at key urban design propositions and how they were proposed to promote walkability. The second part of this paper discusses the concept of walkability, which is fundamental to designing a walkable city. We emphasize both the physical (walkways, adjacent uses, space) and the perceived aspects (safety, comfort, enjoyment), and then we look at the variety of spatial elements constituting a walkable city. The third part of this paper looks at the emerging themes for designing walkable cities and neighborhoods. We discuss the application of urban big data enabled by growing computational powers and related empirical methods and interdisciplinary approaches including spatial planning, urban design, urban ecology, and public health. This paper aims to provide a holistic approach toward understanding of urban design and walkability, re-evaluate the spatial elements to build walkable cities, and discuss future policy interventions.
We estimate the marginal rate of substitution of income for reduction in current annual mortality risk (the “value per statistical life” or VSL) using stated-preference surveys administered to independent samples of the general population of Chengdu, China in 2005 and 2016. We evaluate the quality of estimates by the theoretical criteria that willingness to pay (WTP) for risk reduction should be strictly positive and nearly proportional to the magnitude of the risk reduction (evaluated by comparing answers between respondents) and test the effect of excluding respondents whose answers violate these criteria. For subsamples of respondents that satisfy the criteria, point estimates of the sensitivity of WTP to risk reduction are consistent with theory and yield estimates of VSL that are two to three times larger than estimated using the full samples. Between 2005 and 2016, estimated VSL increased sharply, from about 22,000 USD in 2005 to 550,000 USD in 2016. Income also increased substantially over this period. Attributing the change in VSL solely to the change in real income implies an income elasticity of about 3.0. Our results suggest that estimates of VSL from stated-preference studies in which WTP is not close to proportionate to the stated risk reduction may be biased downward by a factor of two or more, and that VSL is likely to grow rapidly in a population with strong economic growth, which implies that environmental-health, safety, and other policies should become increasingly protective.