criteria. For GHG accounting purposes, TIP projects are separated into two categories: 1) projects with readily quantifiable carbon dioxide (CO2) impacts and 2) projects with assumed CO2 impacts.
MassDOT provides spreadsheets to quantitatively calculate emissions impacts for the following project types:
Adoption of alternative fuel vehicles
Anti-idling strategies
Bike sharing
Bike and pedestrian facilities
Bus replacements
Complete Streets projects
Induced travel
Intersection and traffic flow
improvements
New bus or shuttle services
Park and ride lots
Speed reduction
Transit signal priority
Truck stop electrification
For projects that cannot be quantitatively assessed, the MassDOT guidelines include qualitative direction to help MPOs determine the category of impact as either increase, decrease, or no impact. An example of the methodology can be seen in Figure 2). The 2022-2026 STIP outlines categories of projects intended to result in decreased GHG emissions for the transportation sector, including quantified decrease in emissions from new/additional transit, bus replacement, pedestrian and bicycle projects.
Figure 2: Example of Qualitative Methodology for Determining GHG Impact Direction Source: Transportation Improvement Program Greenhouse Gas Assessment and Reporting Guidance
IMPLEMENTATION AT THE MPO LEVEL
The MPOs in Massachusetts work with MassDOT and other stakeholders to assess the GHG impacts of projects included in the TIP by examining additions or reductions in CO2. Amendment 1 to the Boston Region MPO's LRTP, Charting Progress to 2040, outlined the MPOs' efforts to complete modeling and develop long-range statewide projections for GHG emissions produced by the transportation sector. The Boston Region MPO's travel demand model and the statewide travel demand model were used to
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project GHG emissions levels for 2018, 2019, and 2020 No-Build (base conditions). Reducing GHG emissions and improving multimodal options are key drivers for determining the MPO's goals and investments. To monitor and evaluate the GHG impacts of TIP projects, MassDOT and the MPOs developed approaches for identifying anticipated GHG emissions impacts of different types of projects. Given that CO2 is the largest component of GHG emissions overall and is the focus of regulation 310 CMR 60.05, CO2 has been used to measure the GHG emissions impacts of transportation projects in the TIP and LRTP. Projects with quantified impacts consist of capacity-adding projects from the LRTP and other projects from the TIP for which MassDOT's guidance requires a quantitative GHG assessment. Projects with qualitative impacts are those that would be expected to produce a minor decrease or increase in emissions, and those that would be assumed to have no CO2 impact. NEXT STEPS MassDOT will continue to work with the State's MPOs to reduce GHG emissions from transportation, by providing technical resources such as GHG quantification tools and MOVES emissions factors to help MPOs annually evaluate the GHG impacts of their TIPs and the aggregate GHG impact of the STIP. According to the GWSA, interim emission limits are revisited every five years. Regional and state transportation agencies will continue to advance their GHG accounting efforts to inform transportation system investments.
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