Abstract:

Past literature has explored the degree to which ride-hailing complements or competes with public transit. The evidence suggests that while individual trips sometimes do connect to transit or occur in areas or not well served by transit, ride-hailing trips are most concentrated in the densest parts of urban areas where transit service is good. The result is a shift from transit to ride-hailing, adding congestion to the roads that are most congested already. This talk presents two studies exploring how we might counteract that effect through pricing.

The first evaluates Chicago's Ground Transportation Tax (GTT) update of January 6, 2020, which increased fees on solo rides and all downtown ride-hailing between 6am and 10pm. Using a novel policy-sensitive direct ridership model estimated on open data before and after the GTT update, we measure the effect of the pricing change on ride-hailing volume, mode choice, and ride-sharing behavior across Chicago census tracts.

The second study proposes and evaluates a revenue pricing scheme in which per-trip taxes on transit-competitive rides are used to subsidize rides that serve areas or times with limited transit access. Applied over a full day, the scheme would diminish transit competition, reduced vehicle miles traveled, andreduces passenger cost — providing the potential to shift ride-hailing from transit competitor to complement.

Bio:

Greg Erhardt is a Raymond-Blythe Associate Professor of Civil Engineering at the University of Kentucky, a Hans Fischer Fellow at the Institute for Advanced Study, Technical University of Munich, and a Senior Advisor to Bay Area Metro. He earned an MS in Civil Engineering from Northwestern in 2002. The first study was co-authored with Richard Alexander Mucci at the University of Kentucky, and the second with Zhihua Jin, Rolf Moeckel and Allister Loder at Technical University of Munich.

Abstract:

Reinforcement learning (RL) lets autonomous vehicles learn to drive through trial and error, but its success depends on the reward function, the rule that tells the vehicle what counts as “good driving”. Today these rewards are mostly hand-designed by experts. That takes a lot of effort and often fails to capture what safe driving means in complex traffic. Vision-language models (VLMs), trained on huge amounts of images and text, carry broad knowledge about how the world works, such as how objects, actions, and their outcomes relate to one another. This built-in knowledge offers a new way to tackle this problem. This talk will first discuss the challenges of reward design in RL-based autonomous driving and the opportunities that foundation models bring. It will then introduce VLM-RL, a framework that uses pre-trained VLMs to turn plain-language driving goals into reward signals for RL. Humans learn well from both good and bad examples, and the framework works the same way. It compares what the vehicle sees against a positive goal (e.g., “the road is clear with no car accidents”) and a negative goal (e.g., “two cars have collided with each other”). It then combines this feedback with basic vehicle state information to produce stable, informative reward signals. Next, the talk will show how well the framework works through experiments in the CARLA simulator, where compared with existing methods, VLM-RL lowered collision rates, raised route completion, and generalized to driving scenarios it had not seen before. Finally, the talk will discuss future directions for bringing foundation models into safe, human-centered autonomous driving, including moving from simulation to real world.

Bio:

Dr. Sikai (Sky) Chen is an Assistant Professor in the Department of Civil and Environmental Engineering at the University of Wisconsin-Madison, with a courtesy appointment in the Department of Mechanical Engineering. He also serves as the Associate Director of the university's Smart Highway Research Center (SHRC), leading the Digital Infrastructure, Data Science, and Artificial Intelligence Program. He received his Ph.D. in Civil Engineering, with a concentration in Computational Science & Engineering, from Purdue University. His research centers on three interconnected themes—human users, AI, and transportation—with the goal of developing safe, efficient, resilient, and human-centered transportation systems by integrating human behaviors, interactive autonomy, digital infrastructure, and domain-specific foundation models. Dr. Chen is one of the fifteen Stage 1 winners of the USDOT ARPA-I Ideas and Innovation Challenge, and his research has received multiple national and international recognitions, including the Matthew G. Karlaftis Best Paper Award and the Milton PikarskyMemorial Award (a national award for the best Ph.D. dissertation in transportation studies). He serves as PI or co-PI on research projects funded by USDOT, WisDOT, WARF, and industry partners such as NVIDIA. He is a member of two ASCE national committees (Connected & Autonomous Vehicle Impacts, and Economics & Finance) and the IEEE Emerging Transportation Technology Testing Technical Committee. He previously served as a member and Committee Communications Coordinator of the TRB Standing Committee on Statistical and Econometric Methods (AED60).

Abstract:

Microbial communities underpin the health of humans, animals, and ecosystems, shaping our world and how we experience it. Conversely, microbes are also shaped by human activities, including the widespread use of antimicrobial chemicals. Understanding how microbial communities respond to these pressures is essential for mitigating antimicrobial resistance, protecting public health, and developing sustainable biotechnologies. Drawing on studies spanning hospitals, homes, wastewater treatment systems, and host-associated microbiomes, this talk will explore how microbial ecology can reveal the mechanisms by which microbes adapt, survive, and evolve in complex real-world environments.

I will present recent work investigating the fate and impacts of antimicrobial chemicals in built and natural environments, highlighting how chemical exposures reshape microbial community structure and select for resistant organisms. These studies demonstrate the value of integrating analytical chemistry, cultivation-based microbiology, genomic approaches, and ecological theory to uncover microbial processes that are often hidden in laboratory model systems.

Building on these discoveries, I will discuss efforts to develop evidence-based policy and ecology-informed strategies for microbial control and microbiome engineering. The latter include advancing bacteriophage-based therapeutics for difficult-to-treat infections and engineering phage and microbial communities for applications ranging from human health to energy-efficient wastewater treatment. Together, these projects illustrate how a mechanistic understanding of microbial ecology can be translated into innovative interventions that move beyond conventional antimicrobial approaches.

By connecting fundamental questions in microbial ecology and evolution with applied challenges in medicine, the built environment, and environmental biotechnology, this work transforms our ability to predict, manipulate, and design microbial communities for healthier and more sustainable futures.

Bio:

Dr. Erica Marie Hartmann is an environmental microbiologist interested in the interaction between anthropogenic chemicals and microorganisms, as well as bio-inspired mechanisms for controlling microbial communities. Her career began at the Johns Hopkins Bloomberg School of Public Health. She then moved to Arizona State University where she was the first graduate of the interdisciplinary Biological Design PhD program. She had two postdoctoral positions, the first, supported by a Fulbright, at the Commission for Atomic Energy in France. She began leading studies on antimicrobial chemicals and microbes found in indoor dust during her second postdoc at the Biology and the Built Environment Center at the University of Oregon. She is currently an associate professor at Northwestern University in the department of Civil and Environmental Engineering, with affiliations in Pulmonary Medicine and the Center for Synthetic Biology. She was awarded an NSF CAREER to support her work on antimicrobial textiles and is leading an investigation of the respiratory tract microbiome in the NIH-funded Successful Clinical Response In Pneumonia Therapy (SCRIPT) Systems Biology Center. She is further designing new antimicrobial strategies based on bacteriophages.

TBD

Regular registration for Winter quarter begins

12:15 PM Registration and Networking - 70th Anniversary Industry Workshop

12:45 PM Welcome

Bret Johnson, Interim Director, NUTC

1:00 – 2:30 PM Session 1: Talent, Leadership, and Purpose in Preparation for the Next 30 Years

Moderator: Elsy Ocejo, Fractional COO/CSCO
J. Edward Colgate, Walter P. Murphy Professor of Mechanical Engineering; Allen and
Johnnie Breed Senior Professor in Design; Director, NSF Engineering Research Center
on Human AugmentatioN via Dexterity (HAND)
Xiaopeng Li, Harvey D. Spangler Professor in the Department of Civil and Environmental
Engineering, Director, USDOT Rural Autonomous Vehicle Program for People Movement, University of Wisconsin, Madison

2:30 – 3:00 PM Break

3:00 – 3:30 PM Presentation: Retrospective of the Transportation Center over 7 Decades

Rachel Cole, Head of Northwestern Transportation Library

3:30 – 5:00 PM Session 2: 70 Years Forward: NUTC's Legacy and the Next Chapter in Transportation & Supply Chain Systems

Moderator: Joseph Schofer, Emeritus Professor of Civil and Environmental Engineering,
McCormick School of Engineering and Applied Science, Northwestern
Ben Mclean, CEO, Ruan Transportation Management Systems
Ian Savage, Associate Chair, Professor of Instruction, Department of Economics, Weinberg College of Arts and Sciences, Northwestern
Karen Smilowitz, Associate Provost for Undergraduate Education, Northwestern; James N. and Margie M. Krebs Professor of Industrial Engineering and Management Sciences,
McCormick School of Engineering & Applied Science; Professor of Operations, Kellogg
School of Management
Jeff Silver, CEO, Master Logistics Systems; Chair, NUTC Business Advisory Council (BAC)
Justin Zubrod, Managing Partner, Justin Zubrod & Company; former Chair, NUTC BAC

Register Now

TBD

Dissertation, PhD Final Exam, and change of grade forms due to TGS for Fall PhD candidates

Thanksgiving Vacation begins at 6:00 PM (No classes, University offices closed)

Fall Classes Resume

Fall classes end

Fall Exams begin

Fall exams end

The ceremony will take place on Saturday, December 12 in Pick-Staiger Concert Hall, 50 Arts Circle Drive.

Related Info

Winter Recess Starts - University Closed Through January 1st, 2027

Winter classes begin

No classes- Martin Luther King Jr. Day