Gabriel Ahlfeldt lecturer at the London School of Economics, presents on the digital conversion of data derived from Olcott’s Blue Books, the unique dataset of historical land values, land uses, building heights, and other information in Chicago and its suburbs, published annually between 1900 and 1990. The digitization project, which opens up new possibilities for statistical analysis of long-run adjustments in land values, involves using geographic information system (GIS) software to create a rectangular grid following Chicago’s street pattern and produce a unique spatiotemporal dataset, providing insights into changes in the spatial structure of the city.
Now @ streets.mn: All Minnesota’s Affair
Carlos Carrion and David Levinson (2012) Uncovering the influence of commuters’ perception on the reliability ratio. (Working paper)
The dominant method for measuring values of travel time savings (VOT), and values of travel time reliability (VOR) is discrete choice modeling. Generally, the data sources for these models are: stated choice experiments, and revealed preference observations. There are few studies using revealed preference data. These studies have only used travel times measured by devices such as loop detectors, and thus the perception error of travelers has been largely ignored. In this study, the influence of commuters’ perception error is investigated on data collected of commuters recruited from previous research. The subjects’ self-reported travel times from surveys, and the subjects’ travel times measured by GPS devices were collected. The results indicate that the subjects reliability ratio is greater than 1 in the models with self-reported travel times. In contrast, subjects reliability ratio is smaller than 1 in the models with travel times as measured by GPS devices.
Daniel Graham, Patricia Melo, and David Levinson (2012) Agglomeration, Accessibility, and Productivity: Evidence for Urbanized Areas in the US. (Working paper)
This paper undertakes an empirical analysis with the aim of improving the current understanding of the relationship between labor productivity and urban agglomeration economies across a sample of urbanized areas in the US. Agglomeration economies are represented with driving time measures of employment accessibility to establish a direct account for the link between transport and agglomeration economies. The paper investigates the presence of nonlinearities in the relationship between labor productivity and agglomeration economies, and examines the spatial decay pattern of the effects arising from this relationship. The findings indicate that there is considerable nonlinearity in the relation between productivity and transport induced agglomeration effects, implying that the estimation of country-level aggregate elasticities is likely to misrepresent the actual magnitude of any productivity gains from urban agglomeration. The results also suggest that the magnitude of the productivity-agglomeration effects decays very rapidly with time and is very strong within 20 minutes driving time. This suggests that knowledge spillover externalities are likely to be a very important Marshallian source of agglomeration economies.
JEL Classification: J31, R12, R40
Key words: agglomeration economies, network accessibility, labor productivity
Pavithra Parthasarathi and David Levinson (2012) Network structure and the journey to work: An intra-metropolitan analysis. (Working Paper)
This paper aims to look at the variation of network structure within a metropolitan area and relate it to observed travel, measured here as the average travel time to work. The Minor Civil Divisions (MCD) within the Twin Cities (Minneapolis, St. Paul) metropolitan area are chosen for this analysis. Quantitative measures, compiled from various sources, are used to capture the various aspects of network structure within each MCD. The variation of these measures within the metropolitan area is analyzed using spatial analyses. The measures of network structure are then related to observed travel using statistical regression models. The results confirm a relation between network structure and travel and point to the importance of understanding the underlying street network structure.
David J. Giacomin, Luke S. James, and David M. Levinson (2012) Trends in Metropolitan Network Circuity. (Working Paper)
Because people seek to minimize their time and travel distance (or cost) when commuting, the circuity–the ratio of network distance traveled to the Euclidean distance between two points–plays an intricate role in the metropolitan economy. This paper seeks to measure the circuity of the United States’ 51 most populated Metropolitan Statistical Areas and identify trends in those circuities over the time period from 1990- 2010. With many factors playing a role such as suburban development and varying economic trends in metropolitan areas over this timeframe, much is to consider when calculating results. In general, circuity is increasing over time.
Michael Iacono, David Levinson, Ahmed El-Geneidy, and Rania Wasfi (2012) Markov Chain Model of Land Use Change in the Twin Cities. (Working Paper)
The set of models available to predict land use change in urban regions has become increasingly complex in recent years. Despite their complexity, the predictive power of these models remains relatively weak. This paper presents an example of an alternative modeling framework based on the concept of a Markov chain. The model assumes that land use at any given time, which is viewed as a discrete state, can be considered a function of only its previous state. The probability of transition between each pair of states is recorded as an element of a transition probability matrix. Assuming that this matrix is stationary over time, it can be used to predict future land use distributions from current data. To illustrate this process, a Markov chain model is estimated for the Minneapolis-St. Paul, MN, USA (Twin Cities) metropolitan region. Using a unique set of historical land use data covering several years between 1958 and 2005, the model is tested using historical data to predict recent conditions, and is then used to forecast the future distribution of land use decades into the future. We also use the cell-level data set to estimate the fraction of regional land use devoted to transportation facilities, including major highways, airports, and railways. The paper concludes with some comments on the strengths and weaknesses of Markov chains as a land use modeling framework, and suggests some possible extensions of the model.
Carlos Carrion and David Levinson (2012) Route choice dynamics after a link restoration. (Working Paper)
Carrion and Levinson (2012) studied the bridge choice behavior of commuters before and after a new bridge opened to the public. This bridge replaced the previously collapsed I-35W bridge in the metro area of Minneapolis-St. Paul. The original I-35W bridge collapsed on August 1st, 2007, and the replacement bridge opened to the public on September 18th, 2008. This study extends Carrion and Levinson (2012) by considering explicitly the day-to-day behavior of travelers, and by also considering the previously excluded subjects that are transitioning between bridge alternatives not including the I-35W bridge. The primary results indicate that the subjects react to day-to-day travel times on a specific route according to thresholds. These thresholds help discriminate whether a travel time is within an acceptable margin or not, and travelers may decide to abandon the chosen route depending on the frequency of travel times within acceptable margins. The secondary results indicate that subjects previous experience, and perception of the alternatives also influence their decision to abandon the chosen route.
Paul Anderson, Andrew Owen, and David Levinson (2012) The Time Between: Continuously-defined accessibility functions for schedule-based transportation systems. (Working paper)
Accessibility is traditionally considered to be a property of a point or region in space, and to be invariant over time (or at least over some computationally convenient time interval). How- ever, a locations accessibility can vary over time on a wide range of scales. This temporal variation is especially significant for schedule-based transportation systems. Current measures of accessibility generally reflect the accessibility only at points in time corresponding to the departures of one or more trips; accessibility between these time points remains unconsidered and undefined. Consequently, these measures are insensitive to changes in route frequency and the distribution of trip departure times. Furthermore, these approaches ignore the disutility experienced by a system user who is limited to departing or arriving at scheduled times rather than at preferred times. As a result, they systematically overestimate the accessibility experienced by users of scheduled transportation systems. We establish new methods for representing the accessibility provided by a schedule-based transportation system from a specific location as a continuously-defined accessibility function (CDAF) of desired departure time, defined for all time points. Using schedule and route information from metropolitan transit providers, we demonstrate the application of these methods to gain new insight into the accessibility provided by real-world transportation systems. Four examples are developed to represent common service types in metropolitan transit networks. The results confirm that accessibility is significantly overestimated by measuring single points and show that trip frequency is more valuable for sustained accessibility than high accessibility on individual trips.
Secessionism at streets.mn: The City of Saint Anthony Falls: “”