|
  |
|
|
 |
||
 |
|
 |
 In this issue: Fifty years of land use changes tied to accessibility
Land-use models were used to predict possible changes to areas including the Highway 610 corridor. If we could step back 50 years into the past, we would find a Minneapolis-St. Paul region that looks very different than it does today. The national interstate highway system was in its infancy, and the network of urban highways around the Twin Cities was largely nonexistent; many of today’s residential and commercial areas were yet to be developed. The transformation of the region over the last 50 years has included changes in travel patterns and land use that have, in turn, created new patterns of accessibility. Access to Destinations Study researchers studying how accessibility in the Twin Cities has changed over time gathered data on land uses over the last half-century in order to build new models of land use change over time. By modeling the processes that have shaped land use patterns in the past, they hope to understand how accessibility is likely to hbe affected by changes in land use today and in the future. Civil engineering research fellows Michael Iacono and Rania Wasfi, research associate Ahmed El-Geneidy, and graduate student Shanjiang Zhu worked with study co-leader David Levinson on the research, which is documented in a final project report now available from the Center for Transportation Studies. The research team began with a 75-meter grid covering the entire Twin Cities metropolitan area. Each cell in this grid was assigned a predominant land use, using data provided by the Metropolitan Council from 1984 onwards, and derived from digitized historical maps for years before 1984. This grid served as the foundation for the team’s modeling experiments, in which three types of models were tested to see how well they could reproduce known historical changes. The first model operated on the principle that land use in each cell—the “state” of the cell—at any point in time is a function of previous states. The state of each cell changes according to a matrix of probabilities, so every cell with a particular land use has a certain probability of changing to a new type of land use (or remaining the same) every time the grid is updated. In contrast, the second model added several variables related to neighboring cells’ land uses, such as proximity to highways and measures of regional accessibility, to create a logistic regression model. This model was intended to aid in identifying the factors that affected land use change. The third model extended the Markov Chain framework used in the first model by adding neighboring land uses to the probabilistic matrix. This hybrid cellular automata-Markov chain approach is significantly more complex than the first model. After analyzing the performance of these models, the researchers concluded that none were fully able to faithfully predict the complex changes in land use over the last 50 years. While each type of model proved to have its own limitations, the three approaches also offered a variety of benefits to researchers seeking to study the connection between accessibility and land use. Among these benefits is the ability to incorporate new features of urban growth processes, which will make future modeling exercises more realistic and powerful. Monitoring Land Use Activity Changes in the Twin Cities Metropolitan Region (Mn/DOT 2008-26), the seventh report in the Access to Destinations Series, is available from the Study’s Web site.  Accessibility measures get specific with parcel-level data
Parcel level maps of the entire metropolitan area were incorporated into a new GIS dataset. Researchers studying accessibility in the Minneapolis-St. Paul metropolitan area have created a highly detailed picture of destination characteristics using parcel-level data on commercial activities. This fine-grained dataset promises unprecedented precision in the analysis of accessibility across the Twin Cities region; these data are particularly useful for the study of accessibility via non-auto travel modes. Jessica Horning and Ahmed El-Geneidy of the University of Minnesota’s Humphrey Institute of Public Affairs worked with Access to Destinations Study co-leader Kevin Krizek to develop the new dataset; Krizek is a former member of the Humphrey Institute faculty, now at the University of Colorado. In their final report on the project, the research team notes that many previous efforts to study accessibility have focused on access to employment opportunities, which are hypothesized to be closely connected with urban structure and residential location choices. However, other types of destinations also play influential roles in determining travel and development patterns. To create the new dataset, the research team purchased data from commercial vendor Dun and Bradstreet, which classifies businesses according to the six-digit North American Industrial Classification System (NAICS) scheme. In order to make this data usable by geographic information systems (GIS) applications, the researchers then had to clean it up by resolving incomplete or ambiguous address information, and then match it with a parcel level map of the region using specialized software developed by a graduate research assistant in the University’s computer science department. The end result of this effort was a parcel-level GIS layer that represents the many land uses that are likely to be influential at neighborhood and regional scales across the entire seven-county Twin Cities region. This GIS layer will support the development of an “accessibility matrix” showing accessibility levels for many different types of destinations in different areas at different times. Parcel Level Land Use Data Acquisition and Analysis for Measuring Non-Auto Accessibility (Mn/DOT 2008-19), the sixth Access to Destinations report, is available from the Study’s Web site. Study workshops scheduled in November
John Hourdos (left); Kevin Krizek Researchers contributing to the Access to Destinations Study will share their latest findings next month at a pair of public workshops on the University of Minnesota’s Minneapolis campus. On Tuesday, November 11, Minnesota Traffic Observatory director John Hourdos will describe the techniques used to gather data about travel on arterial streets and estimate travel times across the Twin Cities road network. Two weeks later, on November 25, Study co-leader Kevin Krizek will talk about his team’s work on estimating accessibility via non-motorized travel modes. Both workshops will be held in Room 1130 of the Mechanical Engineering Building between the hours of 3:00 and 4:30 p.m. Video of the workshops will be streamed live over the Internet and archived on the Access to Destinations Study Web site; check the Study’s events page for more information. Graduate student awarded for research paperJessica Horning received the Lloyd B. Short Award for best master's paper at the Humphrey Institute of Public Affairs. The paper, Using Archived ITS Data to Improve Transit Performance and Management, was written as part of the Access to Destinations Study. Horning worked under the direction of Ahmed M. El-Geneidy, who was a post-doctoral research fellow in the Department of Civil Engineering and the Humphrey Institute of Public Affairs (he is now with McGill University). Horning and El-Geneidy presented the paper at the annual Transportation Research Board in January 2008. The final research report is available on the Center for Transportation Studies Web site. Horning recently completed her master’s degree from the Humphrey Institute. CommentsWe would like to hear what you think of Access to Destinations E-News. Please e-mail us at cts@umn.edu. CTS Director: Robert C. Johns Center for Transportation Studies Check out other CTS publicationsCTS publishes many other materials such as proceedings, handbooks, and CD-ROMs. They are available at www.cts.umn.edu/publications. The following newsletters are also available; you may subscribe to them by completing our subscription form.
The University of Minnesota is an equal opportunity educator and employer. This publication is available in alternative formats upon request. We respect your privacy. See the University of Minnesota's online privacy policy. |
|
||||
|