Project Description

Accessibility, defined as the potential to reach opportunity sites, is being used mostly as a place-based measure. Placed-based accessibility implicitly assumes that accessibility to opportunities is a function of places, not individuals. The exclusion of individuals in calculating accessibility is unrealistic because individuals facing different time constraints will have varying levels of accessibility to opportunities, even though they reside in the same place. Females’ accessibility might be different from males, because the time constraints they face are different. Therefore, accessibility is a function of places and individuals.

The inclusion of individuals in accessibility suggests that there is a temporal and social dimension of accessibility. Differences in time constraints can lead to differences in accessibility, which will then lead to varying levels of accessibility for various social groups. Understanding in the temporal and social dimension of accessibility is important, because if the deficiency in one’s accessibility is related to his or her temporal and social characteristics, the recent movement in changing the built environment in order to improve accessibility would be ineffective.

The temporal and social dimension of accessibility also relates to the social equity aspect in the transportation planning process. Currently, although social equity is stated as one of the goals in the planning process, it is largely ignored in the actual process. At times, such omission can be challenged in court. The lawsuit filed by transit riders’ group in Los Angeles (LA) against LA Metropolitan Transportation Authority in the 1990s was an example. MPOs (Metropolitan Planning Organizations) in this country would benefit if a simple individual and place based accessibility measure can be developed to allow them understand the social aspect of accessibility.

The objectives of the proposed study are two-folds. First, we want to achieve a good understanding in how accessibility can be affected by place and individual-based factors and how they vary for different social groups. Second, we want to develop a simple measure that MPOs can use to incorporate the social aspect of accessibility in the planning process.

The empirical dataset for this study will be the 1997/1998 Regional Household Travel Survey conducted in the New York Metropolitan Region, which comprises 28 countries in New York, New Jersey and Connecticut. Instead of including all 28 counties, the study sample for this study will be residents living in New York City. The nature of this study dictates that large amount of data (e.g., GIS based transportation network data and land use parcel files) must be processed. The focus in New York City, though limits the geographical area, allows us to conduct in-depth investigation. In addition, New York City comprises five boroughs, each possessing a distinctive set of characteristics in terms of population demographics and the built environment. The variations in population demographics and the built environment should be sufficient for the purposes of the study.

The proposed project contributes to the academic literature and the practice. While there is a vast literature in accessibility related literature, much focuses on its measurement and its relation to changes in travel behavior. The temporal and social dimension of accessibility is largely ignored. The proposed project contributes to this aspect in the literature. In practice, there is little knowledge in MPOs in terms of how to evaluate accessibility by different social groups. Therefore, development of an easy-to-use measure for this purpose is necessary and important.