Papers by John Ottensmann
Current methods for defining employment centers in urban areas are limited by their failure to ta... more Current methods for defining employment centers in urban areas are limited by their failure to take into account the presence of local-serving employment. The requirement of a minimum employment-population ratio is added to the standard minimum density and total employment criteria to delineate employment centers in 55 large urban areas. The method deals with problems of overbounded centers, including extensive areas qualifying as centers in the densest urban areas. Larger and more rapidly growing urban areas tend to have more employment centers. Numbers of centers have increased from 2002 to 2019, especially in urban areas in the South and West.
The paper begins by examining the percentage distribution of employment by industry sector for em... more The paper begins by examining the percentage distribution of employment by industry sector for employment centers within 55 large urban areas. The novel technique of Q-mode principal components analysis is used to classify centers into groups having similar industry compositions. Most common are the diversified commercial centers with office employment complemented by retail and accommodation and food service employment. The additional classes include centers with concentrations of employment in health care, education, public administration, goods production and distribution, and transportation and warehousing.
The objective is the classification of employment centers in large urban areas based on the distr... more The objective is the classification of employment centers in large urban areas based on the distribution of their employment by industry sector. Q-mode principal components analysis is used in the classification. Q-mode analysis inverts standard principal components analysis, with the variables being the employment centers and the observations being the percent of center employment in each industry sector. The component loadings obtained from the analysis are used to place the centers into classes with other centers having similar industry employment distributions. This approach may also be applicable to many other classification problems.
Employment centers are identified sequentially within large urban areas that meet progressively l... more Employment centers are identified sequentially within large urban areas that meet progressively lower standards for employment density and total employment. The numbers of centers are similar to those identified using traditional methods but they are significantly smaller, avoiding the overbounding associated with the earlier centers. These centers are used to examine the general distribution of employment in the urban areas, the extent to which that is monocentric, polycentric, or dispersed. For the average urban area, more employment is located in centers other than the CBD center, and the percent of urban area employment in the centers outside the CBD centers is increasing while the percent in the CBD centers is declining. The largest share of employment in the urban areas is dispersed in those areas outside of any of the centers.
A simple land use model-the luci2 model-simulates new residential and employmentrelated developme... more A simple land use model-the luci2 model-simulates new residential and employmentrelated development for traffic analysis zones for the state of Indiana. This model has been integrated with the Indiana state travel demand model to create the INtegrated TRansportation Land-Use Demand Estimation model (INTRLUDE). The integrated model is being used by the Indiana Department of Transportation to assess planned project alternatives. It is impossible to provide a comprehensive review of land use models in this paper. A number of major reviews of urban development models have been published in recent years. Wegner provided an overview of the status of urban simulation modeling (1). The review by Agarwal, et al. (2) focused on models addressing land use changes having environmental consequences, especially for forests. The largest review, by the U.S. Environmental Protection Agency (3) considered urban development models with a community planning focus, emphasizing the impacts of policies on land use change and the impacts of land use change on communities. Likewise, numbers of reviews of integrated transportation and land-use models have been published (4-6). Three of the more widely used such models are the Integrated Transportation and Land-Use Model Package, UrbanSim, and MEPlan. The Integrated Transportation and Land-Use Model Package (ITLUP, now also METROPILUS) was the first operational integrated model, combining basic residential and employment models (DRAM/EMPAL) with a traditional travel demand model (7-8). UrbanSim is a highly disaggregated model. It is a more behaviorallybased model, explicitly simulating the actions of households, businesses, developers, and governments (9-10). MEPlan uses an expanded form of the Lowry framework, with multiple residential and business activities represented in a spatially disaggregated matrix, to which inputoutput methods are applied . The Indiana Department of Transportation (INDOT) has developed and enhanced the Indiana State Travel Demand Model (ISTDM). This is a standard travel demand model implemented in TransCAD (13). The model has 4,579 internal traffic analysis zones (TAZs) and 141 external TAZs. These are illustrated in Figure .
Employment centers are identified in over 50 large urban areas for 2002, 2011, and 2019 that cons... more Employment centers are identified in over 50 large urban areas for 2002, 2011, and 2019 that consist of groups of census tracts meeting three sets of minimum employment density and minimum total employment criteria. Numbers of centers range from only the central business district for some smaller urban areas to more than 50 in the New York and Los Angeles areas in 2019 using the lowest, most generous criteria. The number of employment centers and the share of total employment in centers in an urban area is strongly related to the size of the area. Mean percent of total employment in the CBD employment center(s), 13 percent, is less than the mean percent in other employment centers, 17 percent. But there is extremely wide variation in these shares across the urban areas. In nearly all urban areas a large majority of employment is dispersed outside any employment center. Mean number of centers and percent employment in centers increased consistently from 2002 to 2019 and is related to urban area employment and the growth of that employment over the period.
The negative exponential decline of population and employment density with distance from the cent... more The negative exponential decline of population and employment density with distance from the center is examined for 16 large urban areas with two or three major centers. An additive model is used, with the predicted density for each census tract being the sum of the density estimated for the negative exponential decline from each center. The model works well for population density, producing results comparable to those for the large urban areas with single centers. As with employment density decline for the single-center areas, separate estimates of employment density decline are required for areas near the centers and farther from the centers.
Data for census tracts from the Longitudinal Employer-Household Dynamic program are used to test ... more Data for census tracts from the Longitudinal Employer-Household Dynamic program are used to test the hypothesis that employment density declines as a negative exponential function of distance from the center for 39 large urban areas. Problems are encountered in the estimation of the model, with log linear estimates unsatisfactory and nonlinear estimation producing some unreasonable results. An ad hoc procedure is used to slightly modify the data, yielding results that are more plausible. However these estimated functions underpredict densities in areas away from the center. The decline of employment density is better described using two negative exponential functions of distance, one having a steeper decline for areas in the inner portion of the urban area and the second a more gradual decline in the outer areas. This supports the hypothesis that employment in the outer areas should be related to population, with the decline of employment density mirroring the decline of population density.
Data from the Longitudinal Employer-Household Dynamics (LEHD) program are used to examine the loc... more Data from the Longitudinal Employer-Household Dynamics (LEHD) program are used to examine the location of employment in 55 large urban areas. Three measures of location are used-the percent of employment in the urban core, the older portion of the urban area; the percent of employment in the central area encompassing the central business district (CBD) and surrounding area with significant nonresidential use; and an index of employment centralization comparing the mean distance to the center for jobs with the mean distance had those jobs had been uniformly distributed across the urban area. Average levels of these measures and their variation are examined across the urban areas, over time from 2002 to 2019, and across regions. Employment location by industry is presented for employment in the 20 sectors of the North American Industry Classification System (NAICS). The location of employment is compared with the location of the population in the urban areas.
Stable integration has been investigated by classifying census tracts as integrated or not, stabl... more Stable integration has been investigated by classifying census tracts as integrated or not, stable or not. This paper avoids such arbitrary categorization by developing an index of stable diversity that measures the degree to which a tract is diverse and stable. Measures of stable diversity for 56 large urban areas from 1990 to 2020 show wide variation but substantial increases in mean stable integration for the census tracts in these areas. Levels of stable diversity for the individual urban areas likewise increase and are greater for areas in the West. Faster growing areas are more diverse, and the percent and change in population white, black, Latino, and Asian all significantly affect diversity and the change in diversity. A measure of stable diversity between whites and blacks shows levels to be higher in tracts with more Latinos and Asians, whose presence appears to reduce pressure for racial change.
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Papers by John Ottensmann