Research Highlights
ClimBridge
Physics-aware surrogates linking transport choices to air quality and routing decisions
September 04, 2025

The Science Objective
Cities need fast, trustworthy tools that show how transport choices ripple into air quality and day-to-day operations. High-fidelity simulators capture the science but are too slow for rapid “what-if” analysis or on-the-fly decision support. This project builds physics-aware, data-driven AI surrogates that aim to reproduce key simulator outputs while running in seconds. The first chapter focuses on a small-area NOx pilot in Birmingham using ADMS to prototype the pipeline, metrics, and uncertainty handling. Later chapters scale to CMAQ/WRF-Chem and multi-pollutant fields (e.g., NO₂, O₃, PM₂.₅) at broader scales. The overarching question is how to preserve essential physical structure and uncertainty credibility while integrating behaviour, infrastructure, and meteorology into decision-useful models.
Approach
- Curate traffic activity, fleet mix, network/street-canyon descriptors, and meteorology; generate diverse ADMS scenarios for NOx across typical and stress conditions for the City Of Birmingham in the United Kingdom.
- Train compact surrogates to emulate ADMS outputs at street to neighbourhood scales, preserving hotspots, diurnal patterns, and gradients.
- Validate with multi-metric criteria: errors for levels, structural similarity for spatial fields, peak recall for hotspots, temporal skill for rush hour dynamics, and basic physical checks (non negativity, simple mass/flow consistency).
- Generalise the pipeline to regional episodes from CMAQ/WRF-Chem and to multi-pollutant fields, reusing the same evaluation playbook.
- Integrate behaviour and infrastructure (adoption, policies, charging availability) to support realistic scenario analysis.
- Embed the surrogate in a carbon-aware routing module that weighs travel time, emissions outcomes, and reliability under uncertain scenarios (charger outages) and adverse weather.
- Provide a simple API that returns maps and time series with uncertainty for rapid “what-if” exploration by planners and operators.
- Document compute budgets, configurations, and datasets for reproducibility, enabling smooth hand-off to collaborators.
Impact
- Rapid scenario screening: explore policy and operational options in minutes, not days.
- Hotspot-aware planning: preserve street-scale detail so interventions target the right places and times.
- Operational decision support: robust, carbon-aware routing with quantified risk under outages and weather.
- Scalable blueprint: a validated NOx pilot that facilitates expansion to multi-pollutant, regional decision tools.
Summary
ClimBridge connects transport behaviour and infrastructure to air quality outcomes and routing choices through fast, physics aware surrogates. It starts small using an ADMS-based NOx pilot in Birmingham, then scales to CMAQ/WRF-Chem and multi-pollutant fields across larger regions. The result is a decision tool that preserves essential physics, quantifies uncertainty, and supports both planning and operations.
Team Members

Nima Valizadeh (Student)
Cardiff University

Karn Vohra, Collaborator
University of Birmingham

William (Bill) Bloss, Collaborator
University of Birmingham

Omer Rana (Advisor)
Cardiff University
Publications
- Position/magazine article (in preparation): ClimBridge: fast physics-aware surrogates for transport–air quality decisions.
- Survey Paper (ACM Computing Surveys, in preparation): AI surrogates for environmental simulations: from city-scale dispersion to decision-ready digital twins.
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