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Transportation Greenhouse Gas Emissions Impact Assessment
In 2023, the Minnesota Legislature created new requirements to ensure transportation projects that expand highway system offset the impacts. Projects that expand the amount of lanes on the highway system or add new interchanges now need to conform with the state’s greenhouse gas emissions (GHG) reduction and vehicle miles traveled (VMT) reduction targets. The legislation requires projects to address the impacts by either modifying the scope or design, halt the project, or offset impacts.
The legislature identified nine categories that projects could use to offset the potential impacts. The categories involve a combination of policy incentives and infrastructure investments that allow local communities to plan offsets according to the local community context.
Why Minnesota is working to reduce emissions
The transportation sector is the largest source of carbon emissions in Minnesota, with surface transportation sources, such as cars, trucks and buses making up about 24% of carbon emissions in 2022. Transportation carbon emissions are primarily the result of fossil fuel combustion in vehicles and are most significantly influenced by:
- Fuel type and fuel efficiency of the vehicles used (such as conventional gasoline or diesel, biofuels or other alternative fuels) and
- The multimodal transportation options (such as transit or biking) people have to get to their destinations (such as homes, business, and schools)
Fuel type and vehicle efficiency matter and so does the mix of transportation options people have to get to their destinations. The rate of vehicle miles traveled decreases – and associated emissions - when there are transportation options and more connected development patterns.
Carbon emissions are also produced from transportation infrastructure construction and maintenance and the generation of electricity used in equipment, facilities and EVs, as well as other upstream emissions from fuel processing. These carbon emissions are not accounted for as transportation sector emissions but are important to consider when looking at the overall impact of transportation systems on statewide emissions.
MnDOT’s role in reducing emissions
To meet Minnesota’s climate targets, multiple strategies are needed to reduce carbon emissions in transportation beyond the transition to electric and zero emissions vehicles.
The legislature directed the transportation community to look more directly at the unintended emission impacts of capacity expansion of highways, the role of land use and figure out how to offset impacts.
Greenhouse gas (GHG) emission and per capita vehicle miles traveled (VMT) reduction support MnDOT’s mission to connect and serve all people through a safe, equitable and sustainable transportation system.
How impacts from capacity expansion will be assessed
Step 1
A project that adds lane capacity of more than a half mile (2,500ft) or creates a new interchange on the highway system will need to assess the added tailpipe emissions and VMT (typically 3-6 total projects across Minnesota).
Step 2
Capacity expansion projects will assess increased emissions from increased VMT that the added lanes or interchange will generate over 20 years. Using the same vehicle fleet assumptions for gas, hybrid and electric vehicles over the time period, which will isolate the emissions added under the build scenario.
Step 3
Projects can offset GHG/VMT using any of the nine offset categories identified by the legislature. For example, expanding road capacity can be offset by implementing transportation or land use changes that reduce emissions such as making transit or bike investments.
Offsets categories
- Transit expansion
- Transit service improvements
- Active transportation infrastructure (biking and walking)
- Micromobility
- Transportation demand management
- Parking management
- Land use changes (residential, mixed-use, transit-orientated)
- Infrastructure improvements related to traffic operations
- Natural systems