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Modeling of Mobility and Energy Policies in an Agent-Based Framework: Case Studies for Chicago Region in 2050
Md Rakibul Alam, Omer Verbas, Taner Cokyasar, Hadi Bhidya, Jesse Altman, Nora Beck, Joshua Auld, Pedro Veiga de Camargo, Jamie Cook, Felipe de Souza, Gopindra Nair, Hyunseop Uhm, Jan Zill
TL;DR
Metropolitan regions need integrated evidence on how transportation policies interact across travel behavior, energy use, and infrastructure. This paper uses POLARIS to evaluate nine 2050 Chicago scenarios against BAU, finding system-level policy effects with implications for transportation planning and grid investment.
Problem
Transportation transitions require integrated tools because conventional and independent models cannot comprehensively capture their interacting effects on behavior, infrastructure, and policy evaluation.
Method
POLARIS co-simulates activity-based passenger demand, endogenous freight generation, multimodal traffic assignment, and transit operations in a 2050 Chicago scenario framework.
Results
The study reports that smart pricing most effectively reduces auto VMT, freight management reduces freight VMT, and transit expansion increases ridership relative to BAU.
Takeaways & Limitations
Charging demand concentrated in the urban core and potential 4 GW evening peaks support coordinated transportation-agency and utility infrastructure planning.
Takeaways & Limitations
Scenarios are evaluated independently rather than in combination, limiting analysis of cross-policy synergies and conflicts.
Abstract
from arXiv · showhide
Metropolitan regions are simultaneously pursuing several interventions to improve mobility, accessibility, and energy efficiency, necessitating integrated tools to understand how these policies interact to affect travel behavior, energy use, and infrastructure needs. This paper evaluates the combined impacts of electrification, freight demand management, road pricing, parking reform, and transit expansion on the Chicago metropolitan transportation system in 2050, using a business-as-usual (BAU) scenario as the baseline. We employ POLARIS, a large-scale agent-based modeling framework calibrated to 2019 conditions, to simulate nine policy scenarios for the seven-county northeastern Illinois region. The framework co-simulates activity-based passenger demand, endogenous freight generation, multimodal traffic assignment, and transit operations, with charging infrastructure and freight operations optimized for each case. Our findings reveal that under the high electrification scenario, total fuel mass declines by 68% while total charging energy increases by approximately 4-8x from BAU, resulting in a peak power demand near 4 GW concentrated in the urban core. Furthermore, freight management policies reduce freight VMT by increasing trip frequency but shortening distances, smart road pricing most effectively reduces auto VMT, and transit expansion boosts ridership by 18% relative to BAU. By presenting the first integrated, agent-based scenario framework for Chicago that jointly evaluates these interventions, this study provides actionable insights for regional transportation planning, grid infrastructure investment, and emissions reduction, highlighting the value of targeted charger upgrades and coordinated policy bundles.
1. Introduction
The study addresses the challenge of evaluating interacting transportation transitions with an integrated regional model. It applies POLARIS to a comprehensive 2050 Chicago scenario framework and quantifies system-level outcomes against a BAU baseline for planning decisions.
- Integrated evaluation is needed because electrification, freight restructuring, and road pricing reshape travel behavior, infrastructure planning, and policy assessment.
- POLARIS co-simulates activity-based passenger demand, endogenous freight generation, multimodal traffic assignment, and transit operations.The Chicago model was calibrated and validated against transit boardings, mode shares, departure-time distributions, and trip-length profiles.
- All scenarios use 2050 business-as-usual as the primary baseline for comparison.
- The study presents a comprehensive 2050 Chicago scenario framework spanning vehicle electrification, freight operations, pricing, and transit expansion.
- The analysis quantifies VMT, PMT, VHT, PHT, speed, trip duration, monetary and time cost, and energy consumption to inform regional planning and utility infrastructure priorities.The intended users include CMAP and Commonwealth Edison.
2. Literature Review
The literature review motivates integrated agent-based modeling by identifying limitations in decoupled freight and conventional policy analyses. It also situates the study within electrification, road-pricing, and transit-planning research.
- Freight modeling: Fixed freight origin-destination matrices use exogenous demand and miss feedbacks among freight volumes, congestion, and freight-mode shifts.Agent-based models instead synthesize firms, supply-chain relationships, and delivery tours to represent endogenous freight trips.
- Freight modeling: Layered freight decision structures connect commodity, logistics, traffic, and infrastructure markets across operational levels.Later models extend this foundation by combining long-, medium-, and short-term freight decisions within broader simulation platforms.
- Electrification: Prior Chicago POLARIS work found that high electrification increases regional charging energy consumption by up to 650% relative to BAU.Related research also shows that charging profiles vary across user groups and interact with transit demand.
- Road pricing: Road pricing is studied as a mechanism for managing travel demand, reducing emissions, and recovering revenue as electrification erodes fuel-tax bases.Prior work reports that income-based discounts and revenue support can improve fairness.
- Transit planning: Transit research identifies service supply as a dominant lever for ridership response and emphasizes integrated optimization with emerging mobility services.Prior Chicago results linked transit expansion to increased boardings, including a 27% increase from a further expansion package relative to BAU.
3. Methodology
The methodology uses POLARIS to simulate passenger and freight activity, multimodal traffic, transit operations, and policy scenarios on a fused Chicago-region network. Nine 2050 scenarios are compared with BAU, including electrification, freight, pricing, and transit interventions.
- POLARIS framework: POLARIS integrates activity-based travel demand, freight modeling, multimodal traffic, and transit assignment in a unified 24-hour simulation.
- Passenger demand: Synthetic individuals and households generate daily activities whose timing, locations, and modes are modeled from demographic and household characteristics.
- Freight modeling: The freight component synthesizes firms and establishments that produce truck and delivery trips, including e-commerce and service movements.
- Traffic and transit operations: Mesoscopic multi-class traffic flow models distinct speed-spacing relationships for cars, trucks, and buses, while rail operates on GTFS-scheduled noncongestable links.
- Behavioral feedback: Iterative feedback lets agents revise routing, mode, schedules, activity durations, or cancellations in response to experienced travel conditions.These responses are embedded in a dynamic network equilibrium process.
- Network representation: The Chicago 2050 network fuses the detailed urban POLARIS network with the higher-resolution suburban Emme network.This combines complementary spatial detail from the two source networks.
- Population projection: 2050 population projections increase households from 4.3 million to 5.3 million and population from 10.4 million to 12.4 million relative to 2019.The CBD and Inner City experience the highest relative growth rates.
- Scenario design: Nine scenarios are organized into six thematic groups, with BAU serving as the primary comparison baseline.
4. Results
Across the 2050 scenarios, most aggregate travel metrics remain close to BAU, while smart pricing most effectively reduces auto travel, freight bundles reduce freight VMT, transit expansion increases ridership, and electrification sharply shifts energy demand toward electricity.
- System-level trip metrics: Most policy interventions produce only slight deviations from BAU in aggregate VMT/PMT and VHT/PHT, reflecting persistent automobile dependence.
- System-level trip metrics: A 10% reduction in auto-driver trip duration under smart pricing makes it the most effective scenario for reducing auto travel.
- Freight impacts: Freight Bundle reduces freight VMT and average freight speed by approximately 8% through more frequent, shorter, slower trips.The scenario increases medium-duty truck trip counts while shortening individual trips, producing a net system-level VMT reduction.
- Cost impacts: Smart pricing raises auto tolls and fares to $0.5/mile, compared with less than $0.05/mile in other scenarios.The results indicate that the pricing instrument, rather than operating or time costs, supplies the main mode-specific behavioral signal.
- Transit performance: Transit expansion increases ridership by nearly 18% relative to BAU and raises system PMT by 14% and PHT by 6%.The scenario combines rail extensions, BRT corridors, route speed improvements, and expanded network coverage.
- Transit performance: Transit expansion reduces drive-to-transit wait time by 31% and drive-to-transit in-vehicle time by 19%.Drive-to-transit wait time falls from approximately 16 to 11 minutes, while in-vehicle time falls from 37 to approximately 30 minutes.
- Energy consumption: High electrification reduces total fuel mass by 68.1% from BAU while increasing total electric energy consumption by 395.8%.The scenario reduces light-duty fuel consumption by 92.6% and medium- and heavy-duty fuel consumption by 44.5%.
- Energy consumption: High electrification expands charging infrastructure into a dense, geographically widespread network, with charging energy increasing approximately 4–8× from BAU.The medium scenario extends coverage into suburban zones, while high electrification substantially increases station numbers and plug counts.
5. Conclusions
The study evaluates 2050 Chicago transportation policies against a BAU baseline and identifies distinct planning implications for charging, freight, road pricing, and transit. It also notes that independently evaluated scenarios do not capture cross-policy synergies or conflicts.
- The 2050 scenario analysis uses POLARIS to evaluate vehicle electrification, freight operations, road pricing, and transit expansion against a BAU baseline.
- A potential 4 GW evening peak under high electrification is spatially concentrated in the urban core, highlighting the need for coordinated grid and charging infrastructure planning.
- Freight mandates reduce overall freight VMT but can fragment supply chains into more frequent, localized truck trips.
- Smart road pricing can replace infrastructure funding while managing travel demand, and expanded rail and BRT provide high-capacity alternatives for resulting modal shifts.
- The scenarios are evaluated independently, limiting assessment of cross-policy synergies and conflicts; future work should test bundled policies and richer freight and land-use dynamics.
FUNDING
The work was supported by the U.S. Department of Energy’s Energy to Communities program, managed by NREL with support from ANL.
- The work was supported by the U.S. Department of Energy’s Energy to Communities program, which is managed by NREL with support from ANL.