Browsing by Author "Tilahun, Nebiyou J"

Now showing 1 - 11 of 11
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    An Agent-Based Model of Worker and Job Matching
    (University of Minnesota, 2013) Tilahun, Nebiyou J; Levinson, David M
    This paper proposes and tests an agent-based model of worker and job matching. The model takes residential locations of workers and the locations of employers as exogenous and deals specifically with the interactions between firms and workers in creating a job-worker match and the commute outcomes. It is meant to illustrate that by explicitly modeling the search process and the interactions between firms and individuals, origins and destinations (ODs) can be linked at a disaggregate level that is reasonably true to the actual process. The model is tested on a toy-city and the using Twin Cities are. The toy-city model illustrated that the model leads to reasonable outcomes, with agents selecting the closest work place when wage and skill differentiation is absent. Relaxing these assumptions increases the observed commute. Especially the introduction of wage dispersion in the model increases the the average home to work distance significantly. Using data from Minnesota, the results on aggregate are shown to capture the trends in the observed data, and illustrate that the behavior rules as implemented lead to reasonable patterns. The results and potential future directions are also discussed.
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    Contacts and Meetings: Location, Duration and Distance Traveled
    (2009) Tilahun, Nebiyou J; Levinson, David M
    The role of contacts on travel behavior has been getting increasing attention. This paper reports on data collected on individual’s social meetings and the choice of in-home/out-of-home meeting locations as well as the distance travelled and duration of out-home-meetings and its relationship to the type of contact met and other attributes of the meeting. Empirically we show that in-home meetings tend to occur most often with close contacts and less often with distant contacts. The purpose, meeting day, and household size suggest that leisure, weekend and large household size people tend to have their meetings either at their home or at their contact’s home. In addition when meetings occur outside of the house, the duration is longer for close contacts and distance to the meeting location is directly influenced by duration and indirectly by the relationship type. Overall the paper illustrates that relationship type along with other meeting specific and demographic variables is important in explaining the location, duration and distance travelled for social meetings.
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    Home Relocation and the Journey to Work
    (2008) Tilahun, Nebiyou J; Levinson, David M
    Relocation decisions are complex. Each household has a bundle of attributes that make a location attractive to it, including the ability to access different activity locations easily, neighborhood quality, house amenities etc. Relocating households have an opportunity to find housing closer to their work. Using data collected in the Twin Cities area, we investigate how distance to home and travel time to home change among individuals who have changed their residence since they started their current job. Comparing the home-to-work distance after the move to the previous-home-to-work distance, we find that the average home to work distance is reduced as a result of the move. We also find that the reduction depend on the previous home to work distance as well as the previous homes’ proximity to downtown Minneapolis. The findings show that households that are either very close to their work, or very close to downtown, or both did not significantly increase or decrease their commute after relocation. This suggests that access to work as well as access to the opportunities that proximity to downtown offers (to jobs, urban spaces, etc.) are important in the decision making process.
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    A Moment of Time: Reliability in Route Choice using Stated Preference
    (2010) Tilahun, Nebiyou J; Levinson, David M
    Understanding how reliability is valued is important because it provides insight to how aims of policies that aspire to provide better transport options can be more fully integrated with user expectations. In this study we derive a choice model for work commute trips that trades off alternatives based on the most frequent experience that users had on that route and the possibility of late or early arrival if they use a particular route. The idea of reliability is incorporated by how far the expected lateness or early arrival is from the most frequent experience on that route. We find that on route decisions the mode travel time is valued at $7.43 per hour while reduction from the magnitude of average lateness (thereby increasing the reliability of the route) is valued at $6.91 per hour.
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    Monte Carlo Simulation of Adaptive Stated Preference Survey with a case study: Effects of Aggregate Mode Shares on Individual Mode Choice
    (2012) Carrion, Carlos; Tilahun, Nebiyou J; Levinson, David M
    Monte Carlo experiments are used to study the unbiasedness of several common random utility models for a proposed adaptive stated preference survey. This survey is used to study the influence of the knowledge of existing mode shares on travelers mode choice. Furthermore, the survey is applied to a sample of subjects selected from the University of Minnesota. The results indicate that the presence of mode shares in the mode choice model does influence the decision of travelers. The estimates are found to be biased by the Monte Carlo experiments.
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    The Role of Job Search Methods and Contacts on Commuting and Relocation Decisions
    (2009) Tilahun, Nebiyou J; Levinson, David M
    This paper empirically explores the relationship between (i) job finding and commuting outcomes and (ii) the relationship between job search and the commute and location outcomes of relocation decisions after finding employment. The relationship between commute outcomes when finding a new job and the job search method that one employs are explored first. That is followed by an analysis of how long one stays at their residence after finding work, and where they eventually relocate relative to their new employment site as well as their previous residence. Along with the usual socio-demographic variables, the analysis takes on the job search method as well as the local contacts that one has in their residential area as important variables informing these choices. The findings indicate that jobs found through the use of internet and newspapers were on average farther away from the searchers’ residence as compared to those found through contacts and formal means. On relocation after employment, we find that being a renter and moving to a rental unit were important in how quickly one relocated. In addition those that used the internet to find their jobs also relocated faster after controlling for demographic variables such as age. The distribution of ones social contacts were also found to be important in how far away from the previous location a person relocated.
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    Selfishness and Altruism in the Distribution of Travel Time and Income
    (Kluwer Academic Publishers, 2013) Tilahun, Nebiyou J; Levinson, David M
    Most economic models assume that individuals act out their preferences based on their own self interest. However there have also been other paradigms in the economics literature that have tried to capture alternative manifestations of human behavior that include fairness. This study examines people's preferences when it comes to their travel time and their income and what type of trade offs they are willing to make to live in a society where the distributions of travel time and income are fairer. Using a stated preference experiment we find that when it comes to travel time, individuals are more concerned with societal average travel time, followed by their own travel time and finally by large inequalities in the society, while in the case of income they are more concerned with their own income, followed by societal average and finally by inequality.
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    Trails, Lanes, or Traffic: Value of Different Bicycle Facilities Using Adaptive Stated-Preference Survey
    (Elsevier, 2007) Tilahun, Nebiyou J; Levinson, David M; Krizek, Kevin J.
    This study evaluates individual preferences for five different cycling environments by trading off a higher travel time as a cost incurred when choosing a better facility while letting the user have the option of selecting a less attractive facility at a lower travel time. The tradeoff of travel time to amenities of a particular facility informs our understanding of the value attached to different attributes such as bike-lanes, off-road trails, or side-street parking. The facilities considered here are off-road facilities, in-traffic facilities with bike-lane and no side street parking, in-traffic facilities with a bike-lane and side street parking, in-traffic facilities with no bike-lane and no side street parking and in-traffic facilities with no bike-lane but with parking on the side. We find that respondents are willing to travel up to twenty minutes more to switch from an unmarked on-road facility with side parking to an off-road bicycle trail, with smaller changes associated with less dramatic improvements.
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    Travel Impacts and Adjustment Strategies of the Collapse and the Reopening of the I-35W Bridge
    (Springer, 2011) Zhu, Shanjiang; Tilahun, Nebiyou J; Levinson, David M; He, Xiaozheng
    Major network disruptions have significant impacts on local travelers. Understanding the behavioral reactions to such incidents is crucial for traffic management and planning. This study investigates travelers' reaction to both the collapse and reopening of the I-35W Mississippi River Bridge in Minneapolis, Minnesota. Web-based surveys conducted at residences in several communities across the metropolitan area supplement hand-out/mail-back paper-based surveys distributed to workers in areas around the bridge collapse (downtown Minneapolis and the University of Minnesota). Findings from the four surveys highlight differences in travel impacts and behavioral reactions after the unplanned bridge collapse and the planned bridge reopening.
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    Unexpected delay and the cost of lateness on I-394 high occupancy/toll lanes
    (Ashgate, 2009) Tilahun, Nebiyou J; Levinson, David M
    This study estimates Value of Time differences between people who arrived at their destination as planned and those that were delayed. The analysis is based on the I-394 MnPASS High Occupancy/Toll (HOT) lane project recently implemented in the Minneapolis/St. Paul region. Using a Stated Preference survey, the individuals are asked about a trip they have taken before, and asked if they would opt for the free route or pay and go on the HOT lanes. The analysis groups the travelers into subscribers and non-subscribers of the MnPASS (electronic toll collection transponder) system and further decomposes choices into categories based on trip time and experience (delayed or not). Trip times were divided into morning peak, afternoon peak, and off peak and trip experience was divided into delayed and not delayed, creating six categories. The findings suggest an increased willingness to pay among subscribers who were late to reduce travel time in the PM rush hour. As well, we find some evidence that individuals who were late during the AM peak have a lower VOT as compared to their on-time counterparts.
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    Work and Home Location: Possible Role of Social Networks.
    (Elsevier, 2011) Tilahun, Nebiyou J; Levinson, David M
    This research explores to what extent people's work locations are similar to that of those who live around them. Using the Longitudinal Economic and Household Dynamics data set and the US census for the Twin Cities (Minneapolis-St. Paul) metropolitan area, we investigate the home and work locations of different census block residents. Our aim is to investigate if people who live close to one another, also work close to one another to a degree beyond what would be expected at random. We find a significantly non-random correlation between joint home and joint work locations. Further, we show what features of particular neighborhoods are associated with comparatively higher incidences of people sharing work locations. One reason for such an outcome can be the role neighborhood level social networks play in locating jobs; or conversely work place social networks play in choosing the home location or both. Such findings should be used to refine work trip distribution models that otherwise depend mainly on impedance between the origin and destination.