Browsing by Subject "Spatial analysis"

Now showing 1 - 9 of 9

Alcohol-Related Hot-Spot Analysis and Prediction
(Center for Transportation Studies, University of Minnesota, 2017-05) Schneider, William H.; Stakleff, Brandon; Buser, Lauren
This project developed methods to more accurately identify alcohol-related crash hot spots, ultimately allowing for more effective and efficient enforcement and safety campaigns. Advancements in accuracy came from improving the calculation of spatial autocorrelation and interpolation, the identification of spatio-temporal patterns, and the influence of geographical patterns on the spatial distribution of crashes. The project then used the location-based hot-spot maps created using these improved methods to develop a new method of patrolling for intoxicated drivers. This method guides officers to statistically significant locations where intoxicated drivers are most likely to be, allowing officers to be more accurate while patrolling. Additionally, this method allows officers to pass through more alcohol-related crash locations per minute and mile than current patrolling practices. By improving how officers patrol, individuals may be deterred from driving while intoxicated, and alcohol-related crashes may be ultimately reduced.
Are millennials moving to more urbanized and transit-oriented counties?
(Journal of Transport and Land Use, 2018) Deka, Devajyoti
Recent studies show that two distinct narratives have emerged about the millennials’ behavior, attitudes, and preferences regarding their choice of residence and transportation. According to the optimistic narrative, by living and traveling sustainably, millennials are planting the seeds of an urban renaissance. According to the pessimistic narrative, the changes in their behavior are due to economic constraints. To examine whether the inter-county migration pattern of American millennials is consistent with the optimistic narrative, this study compares some spatial and travel characteristics of the origins and destinations of millennials (age 25-34) and older adults (age 35-64) by using data from the 2011-2015 American Community Survey and the 2010 Longitudinal Employer-Household Dynamics. Basic comparisons show that the destinations chosen by millennials are likely to have the characteristics that are consistent with the optimistic narrative. The push-pull regression models show that the effects of the county characteristics on migration are often significant but modest. The effects are not remarkably different for the two age groups.
Evaluating demand responsive transit services using a density-based trip rate metric
(Journal of Transport and Land Use, 2021) Kaufman, Benjamin; Leung, Abraham; Burke, Matthew
Demand responsive transit (DRT) is attracting increased attention as a means to provide public transit to low-density populations. This research aims to provide a suite of evaluation metrics with low data requirement and widespread availability, so that operators, funders, regulators, and practitioners can better evaluate the performance of DRT services. Trip numbers can be divided by a number of available variables (period, trip length, population, and density) to create a number of derived metrics. By applying these variables across three different DRT service areas in Logan City, Australia, where other key factors are held constant, one can see how different formulations lead to very different readings of DRT system performance. The results confirm the dilemma of cost efficiency versus equity in service provision in low-density environments. This paper also highlights current data limitations and calls for better data collection to facilitate the development of new evaluation methods for DRT services and a new composite metric that can be used for inter-service comparison.
The evolution of the commuting network in Germany
(Journal of Transport and Land Use, 2010) Patuelli, Roberto; Reggiani, Aura; Nijkamp, Peter; Bade, Franz-Josef
The analysis of the structure and evolution of complex networks has recently received considerable attention. Although research on networks originated in mathematical studies dating back to the nineteenth century (or earlier), and developed further in the mid-twentieth century with contributions to graph theory, interest in its application to the social sciences is currently growing—particularly in regional science and transportation, because of the spatial relevance of networks. This paper presents a dynamic outlook for the German commuting network from the perspective of the German labor market districts. The focus of this paper is to explore how the German commuting network evolves, from two perspectives: space and connectivity. We consider home-to-work commuters moving between 439 German districts for the years 1995 and 2005. The results of the present analysis make it possible to identify, among the main German districts, the most “open” and connected ones. These emerging districts can be considered as potential “hubs” in the German commuting system—that is, as attractors from the perspective of spatial economics, and as interconnectors from the perspective of networking.
A multi-dimensional multi-level approach to measuring the spatial structure of U.S. metropolitan areas
(Journal of Transport and Land Use, 2018) Nasri, Arefeh; Zhang, Lei
For many years, attempts to measure the urban structure and physical form of metropolitan areas have been focused on a limited set of attributes, mostly density and density gradients. However, the complex nature of the urban form requires the consideration of many other dimensions to provide a comprehensive measure that includes all aspects of the urban structure and growth pattern at different hierarchical levels. In this paper, a multi-dimensional method of measuring urban form and development patterns in urban areas of the United States is presented. The methodology presented here develops several variables and indices that contribute to the characterization and quantification of the overall physical form of urban areas at various hierarchical levels. Cluster analysis is performed to group metropolitan areas based on their urban form and land-use pattern. This allows for a better utilization of land-use transportation planning and policy analyses used by planners and researchers. This clustering of urban areas could eventually help policymakers and decision makers in the decision-making process to evaluate land-use transportation policies, identify similar patterns, and understand how similar policies implemented in urban areas with similar urban form structure would result in more efficient and successful planning in the future.
On some computational, modeling and design issues in Bayesian analysis of spatial data
(2012-10) Ren, Qian
My research on Bayesian spatial analysis can be divided into three challenges: computing, methodology (modeling) and experimental design. My first exploration in research is to find an alternative to Markov chain Monte Carlo (MCMC) for the Bayesian hierarchical model. Variational Bayesian (VB) method would be a choice to tackle the massive computational burden for large spatial data analysis. We discuss applying VB to spatial analysis, especially to the multivariate spatial cases. Different VB algorithms are developed and applied to simulated and real examples. When the number of the locations and the dimension of the outcome variables are large, models with feature of dimension reduction are essential in the real applications. Low-rank spatial processes and factor analysis models are merged together to capture the associations among the variables as well as the strength of spatial correlation for each variable. We also develop stochastic selection of the latent factors by utilizing certain identifiability characterizations for the spatial factor model. A MCMC algorithm is developed for estimation, which also deals with the spatial misalignment problem. In many of the spatial applications (environmental epidemiology, for instance), parameter estimation is the most important objective in the study. Even with carefully constructed models and computing technique, it is always a challenge to handle the large spatial data set. Bayesian experimental design may help us to get the desired information from a spatial survey study with a sample size that can be analyzed by most available software. The problem of finding the optimum experimental design for the purpose of performing one or more hypothesis tests is considered in the context of spatial analysis. The Bayesian decision theoretic approach is used to arrive at several new optimality criteria for this purpose. Different approaches to achieving this goal are explored, including additive weighted loss and convex approximation. Simulated annealing algorithm (SAA) is applied to real examples to find the optimum design based on our objective function.
Spatial accessibility of public transport in Australian cities: Does it relieve or entrench social and economic inequality?
(Journal of Transport and Land Use, 2017) Scheurer, Jan; Curtis, Carey; McLeod, Sam
City planning in Australian cities has seen a gradual shift in approach, away from planning to facilitate mobility by car in the post-war period toward planning for land-use/public transport integration. By assessing the supply of public transport for city accessibility, a considerable variation within each city can be seen. Of interest is the extent to which there is a relationship between the quality of public transport accessibility and the spatial distribution of socioeconomic advantage and disadvantage. This paper examines this issue by mapping spatial data on socioeconomic disadvantage and advantage against indicators of public transport accessibility. The findings show that Australian cities are characterized by a significant level of spatially manifested socioeconomic inequality exacerbated by transport disadvantage. It is argued that a coincidence of public transport infrastructure and service improvements as well as urban intensification and housing affordability policies are required to counteract these trends.
Temporal sampling and service frequency harmonics in transit accessibility evaluation
(Journal of Transport and Land Use, 2019) Murphy, Brendan; Owen, Andrew
In the context of public transit networks, repeated calculation of accessibility at multiple departure times provides a more robust representation of local accessibility. However, these calculations can require significant amounts of time and/or computing power. One way to reduce these requirements is to calculate accessibility only for a sample of time points over a time window of interest, rather than every one. To date, many accessibility evaluation projects have employed temporal sampling strategies, but the effects of different strategies have not been investigated and their performance has not been compared. Using detailed block-level accessibility calculated at 1-minute intervals as a reference dataset, four different temporal sampling strategies are evaluated using aggregate sample error metrics as well as indicators of spatially clustered error. Systematic sampling at a regular interval performs well on average but is susceptible to spatially-clustered harmonic error effects which may bias aggregate accessibility results. A constrained random walk sampling strategy provides slightly worse average sample error, but eliminates the risk of harmonic error effects.
Using GIS and historical data to reconstruct the Ravenglass-Ambleside Roman road, Cumbria, United Kingdom.
(2011-02) Menard, Jason Christopher
The ability to locate Roman road courses is an important aspect of understanding how culture is expressed in landscapes, and to understand the impact of human agency in antiquity. This study deals with using least-cost models to locate Roman road alignments in the north of Britain, using two different datasets with attested Roman roads to calibrate modeling techniques before attempting a prediction on a third route. Moreover, least-cost routes are refined using additional lines of evidence, such as landscape history and archaeological data to create a more defensible reconstruction than is possible with GIS alone. This study demonstrates that it is possible to identify Roman road alignments to tight corridors using GIS. However, it highlights the central issue in any archaeological application of GIS: that models are not a standalone tool for interpretation. Rather they are another line of evidence to assist researchers to build defensible reconstructions when little archaeological evidence remains.

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