Engineering for Society: Learn – Discover – Transform

The Department of Civil, Enviornmental, and Geo- Engineering at the University of Minnesota has posted its new Strategic Plan: Engineering for Society: Learn – Discover – Transform.

Though it is the product of the department as a whole, I did participate in its drafting and framing.  Happy reading.

Intraurban Accessibility and Employment Density

Recent working paper:

This study investigates the relationship between urban accessibility and firm agglomeration, as reflected in patterns of urban employment densities. We use measures of accessibility derived from the regional highway network, combined with small-scale (Census block-level) data on employment from the Longitudinal Employer-Household Dynamics (LEHD) data set to generate proxies for different sources of agglomeration, specifically urbanization and localization economies. These variables are employed in a set of employment density regressions for 20 two-digit NAICS code sectors to identify the propensity of each sector to agglomerate in response to varying levels of accessibility. The density regressions are applied to sample data from the Minneapolis-St. Paul, Minnesota (Twin Cities) metropolitan region for the years 2000 and 2010. We find that in general urbanization effects tend to overshadow those of localization effects. Moreover, these effects tend to vary by sector, with many service-based sectors showing a stronger propensity to agglomerate than manufacturing and several “basic” sectors like agriculture, mining and utilities.

The Safest Path: Analyzing the Effects of Crash Costs on Route Choice and Accessibility

Recent working paper:TripCountSafest

The “safest path” is proposed to optimize the on-road safety of individuals and minimize the cost of crashes. In this study, the framework of a link-based crash cost analysis is built and applied to assess the crash cost of each link segment on the road network of the Minneapolis – St. Paul area based on Safety Performance Functions from the perspective of travelers. The safest path is then found for all OD pairs to compare flow patterns and accessibility distributions with those based on the traditional shortest travel time path. While, the safest path does not coincide with the shortest path, the accessibility distributions have similar patterns.

The Greenest Path: Comparing the Effects of Internal and External Costs of Motor Vehicle Pollution on Route Choice and Accessibility

Recent working paper: Green_Mar_External_20cent

On-road emissions are a dominant source of urban air pollution, which damages human health. The “greenest path” is proposed as an alternative pattern of traffic route assignment to minimize the costs of emissions or exposure, pursues an environmentally optimal. The framework of a link-based emission cost analysis is built for both internal and external environmental costs and applied to the road network of the Twin Cities Metropolitan area based on the EPA MOVES model. The greenest (internal/external) path is skimmed for all OD pairs to compare the work trip flows on the roads and accessibility distribution. It is shown that the emission cost that travelers impose on others is greater than which they bear. Considering only external emissions costs thus produces a lower accessibility than considering only internal emissions costs. This research contributes to understanding the full cost of travel.

Full cost analysis of accessibility

Recent working paper:NewAccessSocial_Updated

Traditional accessibility evaluation fails to fully capture the travel costs, especially the external costs of travel. This study develops a framework of extending accessibility analysis combining the alternate (internal and external) cost components of travel, time, safety, emission and money, with accessibility analysis, which makes it an efficient evaluation tool for the potential needs of transport planning projects. An illustration of this framework based on a toy network was also built in this paper, which proves the potential of applying the extending accessibility analysis into the network of metropolitan areas.

The Pedestrian By Ray Bradbury

The Pedestrian (1953) by science fiction writer Ray Bradbury, on another view of police traffic stops, c. 2053.

“To enter out into that silence that was the city at eight o’clock of a misty evening in November, to put your feet upon that buckling concrete walk, to step over grassy seams and make your way, hands in pockets, through the silences, that was what Mr Leonard Mead most dearly loved to do. He would stand upon the corner of an intersection and peer down long moonlit avenues of sidewalk in four directions, deciding which way to go, but it really made no difference; he was alone in this world of 2053 A.D., or as good as alone, and with a final decision made, a path selected, he would stride off, sending patterns of frosty air before him like the smoke of a cigar.”

It’s a short story, but probably still under copyright in the US, so I will merely link to the copyright violator rather than violate copyright myself. The rest is here.

This is another entry into transport literature, a narrow genre.

Tenure-Track Faculty Position University of Minnesota, Twin Cities

The Department of Civil, Environmental, and Geo- Engineering at the University of Minnesota seeks applications for a tenure-track faculty position in the area of transportation engineering. We are particularly interested in applicants with strong fundamentals that allow them to easily move across disciplinary boundaries and become involved in department, university, and national interdisciplinary research opportunities. The position is expected to be at the rank of assistant professor, although exceptional candidates at all ranks will be considered.

We are seeking individuals with an academic background and research potential in one or more of the following areas: traffic flow theory; traffic control and operations; transportation safety and security; modeling and simulation of transportation systems; intelligent transportation systems. Other areas of transportation engineering also will be considered.

Candidates will be expected to initiate and maintain a vibrant externally-funded research program. Teaching responsibilities will include existing undergraduate and graduate courses, as well as the opportunity to develop new courses in specialty areas. An earned doctorate is required at the time of the appointment.

Applications must be completed online at – Assistant Professor – Associate / Full Professor
Include a letter of intent, a CV with a list of publications, complete contact information for three references, and a statement of teaching and research interests. The review of applications will begin October 31, 2016. Applications will continue to be accepted until the position is filled. Expected appointment is Fall 2017.

The Department of Civil, Environmental, and Geo- Engineering (CEGE) at the University of Minnesota is affiliated with the Center for Transportation Studies, Roadway Safety Institute, and St. Anthony Falls Laboratory, and its faculty are involved with these and other research centers, including the Minnesota Traffic Observatory and the Multi-Axial Subassemblage Testing Laboratory. CEGE is one of twelve departments within the College of Science & Engineering, which offers outstanding opportunities for interdisciplinary research due to the unique combination of mathematics, science, and engineering in one college.

Using Temporal Detrending to Observe the Spatial Correlation of Traffic

Recent working paper: Figure2.jpg

This empirical study sheds light on the correlation of traffic links under different traffic regimes. We mimic the behavior of real traffic by pinpointing the correlation between 140 freeway traffic links in a sub-network of the Minneapolis – St. Paul highway system with a grid-like network topology. This topology enables us to juxtapose positive correlation with negative correlation, which has been overlooked in short-term traffic forecasting models. To accurately and reliably measure the correlation between traffic links, we develop an algorithm that eliminates temporal trends in three dimensions: (1) hourly dimension, (2) weekly dimension, and (3) system dimension for each link. The correlation of traffic links exhibits a stronger negative correlation in rush hours, when congestion affects route choice. Although this correlation occurs mostly in parallel links, it is also observed upstream, where travelers receive information and are able to switch to substitute paths. Irrespective to the time-of-day and day-of-week, a strong positive correlation is witnessed between upstream and downstream links. This correlation is stronger in uncongested regimes, as traffic flow passes through consecutive links more quickly and there is no congestion effect to shift or stall traffic. The extracted correlation structure can augment the accuracy of short-term traffic forecasting models.

Spatiotemporal Traffic Forecasting: Review and Proposed Directions

Recent working paper: Figure3

This paper systematically reviews studies that forecast short-term traffic conditions using spatial dependence between links. We synthesize 130 extracted research papers from two perspectives: (1) methodological framework, and (2) approach for capturing and incorporating spatial information. From the methodology side, spatial information boosts the accuracy of prediction, particularly in congested traffic regimes and for longer horizons. There is a broad and longstanding agreement that non-parametric methods outperform the naive statistical methods such as historical average, real time profile, and exponential smoothing. However, to make an inexorable conclusion regarding the performance of neural network methods against STARIMA family models, more research is needed in this field. From the spatial dependency detection side, we believe that a large gulf exists between the realistic spatial dependence of traffic links on a real network and the studied networks. This systematic review highlights that the field is approaching its maturity, while it is still as crude as it is perplexing. It is perplexing in the conceptual methodology, and it is crude in the capture of spatial information.