By Marianne Hatzopoulou
In large metropolitan areas such as Toronto, transportation and its relationship with land use and the built environment give rise to a complex system. Where individuals live, where they work, and how they move and plan their daily activities both determine and are determined by the transportation options available to them and the ones they will ultimately choose.
How do we plan a transportation system that can provide quality service for all while allowing Toronto to reduce its carbon footprint? It starts with quantifying the carbon emissions generated by transportation and understanding their evolution over time and space.
Developing comprehensive carbon emission inventories is a crucial step towards meeting climate commitments at the global, national, and urban levels. We can’t control what we can’t measure.
An on-road emission inventory quantifies transportation emissions that occur on the road – passenger vehicles, commercial vehicles, and buses. In a recent paper published by my research group in the journal Sustainable Cities and Society (Vol 40, 2018, pp. 524-533), we estimated that all transit services (including buses) contribute 4 percent of total transportation carbon emissions in the Greater Toronto and Hamilton Area (GTHA), while other vehicles contribute 96 percent.
New inventory support for the City
Funded by a grant from TAF and the City of Toronto, our research group set out to create an on-road emission inventory using traffic count data collected by the City of Toronto. If our tool and methodology were good enough, the City of Toronto would be able to resume tracking, analyzing, and reporting on transportation emissions. The City had stopped tracking transport emissions due to the staff time and effort involved in manually processing all the traffic count data.
Our work resulted in TEPS: Transportation Emissions Prediction Scheme. TEPS is able to interpolate traffic from count locations to the entire road network and subsequently estimate carbon emissions (as well as emissions of other air contaminants).
TEPS is a set of algorithms and a software platform that generates a yearly inventory.
It can be used by any city that collects traffic data. Data processing is mostly automatic, greatly reducing staff time needed.
We used TEPS to estimate emissions for Toronto from 2006 to 2018. TEPs allows us to estimate total city-wide emissions as well as emissions occurring on every road in the city.
We are pleased to report the City found TEPS to be useful. It is now using TEPS in its inventory.
We expect this work will help guide policy design to reduce carbon emissions.
Key findings
Our research work resulted in many insights and lessons, in addition to leading to the creation of TEPs. Key findings:
- Improvements in average vehicle efficiency have been just enough to offset the impact of increases in traffic volumes. This highlights that incremental improvements in fuel efficiency are not enough.
- The majority of emissions are from longer trips originating in outer suburbs and adjacent municipalities – trips that are very difficult to make by active transportation or public transportation. Which means we need interventions designed for these areas. Thanks to this research, we can now pinpoint these areas with impressive accuracy and detail.
- Electric vehicles, transit investments, active transportation, pricing strategies, intermodal shift for freight, and low-emission zones are all strategies that have been tested in various cities as well as close to home and in combination, will help reduce the GTHA’s carbon footprint. In fact, identifying policy options is a relatively straightforward task, but prioritizing these strategies in terms of their effectiveness in reducing carbon emissions is immensely challenging. It requires a deep understanding of the trips that are responsible for the majority of the emissions. It is not hard to believe that these are the commuting trips originating in the suburbs. In a recent paper published by my group on “Reducing Transportation GHG Emissions Through the Development of Policies Targeting High-Emitting Trips,” we estimated that converting short trips to active transportation, while good for our health, has limited carbon reduction potential.
- If we want to achieve bold reductions, we need to look outwards. This means investing in transit outside the city and connecting the suburbs much more efficiently, resulting in lower carbon emissions and cleaner air in the city and outside.
Prof. Marianne Hatzopoulou is Associate Professor and Canada Research Chair in Transportation and Air Quality, University of Toronto Transportation Research Institute (UTTRI), Department of Civil and Mineral Engineering, University of Toronto
