An Update on Public Transportation's Impacts on Greenhouse Gas Emissions (2021)

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32 Conclusions and Suggested Research Public Transportation Is Essential to Climate Action Public transit has been a major source of GHG reductions in the United States, and that continued in 2018. The 63 MMT CO2e that public transportation saved in 2018 is a value larger than the entire national emissions of 111 individual countries. New Zealand, Finland, and Singapore each emitted 63 MMT CO2e across their entire economies in 2016 (ClimateWatch n.d.). Public Transportation’s Climate Actions The numerous efforts that transit agencies have made to improve efficiency and tackle their GHG emissions have come together with technology advances and other forces in the past decade to make public transportation an even cleaner mode of travel than it was found to be in previous national assessments of its climate impact. Transit Emissions Reduction Exceeds Other Modes. Transit GHG emissions reduc­ tions have kept pace with fuel efficiency improvements in gasoline personal vehicles on the road. Rail modes are more carbon efficient than personal electric cars and are becoming even lower emissions as our electricity decarbonizes nationwide. The latest battery electric buses rival electric cars in their per­passenger emissions profile as well. Transit Enhances Community Efficiency. Public transportation helps make communities more efficient. The land use efficiency research in this report shows large, statistically signifi­ cant reductions in VMT in communities with transit above and beyond the personal auto trips avoided by transit riders. Transit Is Expanding Its Climate Action Strategies. Transit agencies are taking a wide variety of climate actions, from leveraging biofuels and hybrid technologies to improving operations and operating conditions for transit vehicles to reduce fuel use while improving reliability and service. Some transit agencies are reaching beyond their usual sphere of activity to install renewable power generation on transit agency property as a means of managing their GHG impacts. Transit agencies are also supporting efforts toward decarbonization of commu­ nities by supporting and pursuing equitable transit­oriented housing development to help households live efficiently and affordably. All of this is good news for communities seeking to take action to address climate change. Public transportation is already creating positive climate impacts in communities in which it operates, and it has the potential to do even more. C H A P T E R   4

Conclusions and Suggested Research 33   Public Transportation’s Potential for Scalable Climate Solutions Economies of scale may make it possible for public transit to electrify and adopt clean power faster than the millions of individual drivers it would take to have the same impact on U.S. transportation emissions. Furthermore, public transportation can do this while creating cost savings for residents as it helps households avoid a second auto purchase or reduce reli­ ance on taxis and ridehailing. The access to essential jobs and services that public transportation provides is a critical part of a community’s overall resiliency. The ridership and service changes that occurred in 2020 due to the COVID­19 pandemic have disrupted business­as­usual transportation in many communities, and the GHG impacts of this remain to be seen, but climate action investments have the potential to make a post­ pandemic era one of lower­carbon transportation that supports equitable, healthy, and resilient communities. Public transportation is an essential element to achieving these outcomes. As transit agencies look to technology transformations to deepen their climate benefits, many will need funding and financing to make that change possible. The up­front cost to electrify a fleet, including infrastructure, maintenance facilities, training, and vehicles, is signifi­ cant and needs to be addressed in order to generate the many benefits electrification can bring to communities of all sizes. Applying These GHG Findings The GHG analysis presented here is meant to be a resource for transit agencies, decision makers, communities, and other public transportation and sustainability stakeholders. This information can be used to guide decision making toward lower­carbon fuels, technologies, and operations improvements, as well as demonstrating the importance of transit ridership and occupancy as a climate solution. The analysis in this research project is also meant to provide the information necessary to communicate public transportation’s important role as a climate solution. To those ends, tools for communication and ideation have been created as part of this project. These supplementary materials can be obtained at www.TRB.org by searching for “TCRP Research Report 226”: 1. Three one-page factsheets that present key findings regarding transit as a climate solution. 2. A PowerPoint slide deck summarizing these findings and the research they are based on with the infographics and charts used in this document. This tool also includes templates for transit agencies to add their own data for climate communications. These slides and infographics can be used by transit stakeholders. The key findings of this analysis are provided in several formats to enable use on social media and websites. 3. A simple spreadsheet tool that provides this study’s 2018 GHG impact findings by transit agency and allows the user to apply several of the climate action scenarios to see how their transit agency’s 2018 GHG impacts change with electrification, clean power, and ridership increases. Suggested Research Inclusion of GHGs in NTD Tracking GHG emissions impacts regularly is important to measuring progress and to continuous learning. Transit agencies report their activity data to the NTD each year, so the GHG calculations in this report could be repeated annually as part of the database compila­ tion process, which would provide transit agencies and communities necessary data to manage

34 An Update on Public Transportation’s Impacts on Greenhouse Gas Emissions climate impacts. There is interest in this type of standardization and economy of scale among transit agency staff members and decision makers. Overall, the NTD energy data provide a robust basis for calculating the GHG emissions associated with transit vehicles to a high degree of certainty on a national basis. However, parts of the data structure are not aligned with GHG accounting needs, as indicated in Appendix A. The energy data reported to NTD also exclude some newer fuel types, such as renewable diesel, which may be reported as biodiesel, diesel, or other. Furthermore, there are a small number of outlier values and data gaps when one looks at the data on an agency­by­ agency basis that should be corrected. An assessment of NTD reporting guidelines for the purpose of supporting GHG calcu­ lations would enable the relatively limited changes that would be necessary to make GHG calculations a regular part of NTD reporting. Metrics suggested for such reporting include GHG emissions per passenger mile traveled, GHG emissions per vehicle mile, average vehicle occupancy, and net transit GHG impacts including transportation efficiency and land use efficiency. The APTA 2019 Public Transportation Fact Book (APTA 2019) is another potential platform for this information. Additional fuel and technology life­cycle information matched specifically to transit opera­ tional needs and procurement choices would also support low­carbon decision making. Documenting Other Transit GHG Sources and Savings Opportunities This study examined the GHG emissions of transit vehicles based on fuel use and vehicle miles. The full GHG footprint of transit agencies includes other emissions sources, such as the energy use of facilities and non­transit vehicles. These are typically much smaller than vehicle GHG emissions; examination of five past transit agency GHG inventories found revenue transit vehicles represented 65% to 95% of transit agency GHG emissions (McGraw et al. 2010, Southworth et al. 2011), but facilities and other emissions sources may become larger shares of the total impact of transit agencies as service vehicle GHGs decrease. Further documentation of these activities and best practices in reducing their emissions would help transit agencies and communities prioritize climate action investments. This research would also be an opportunity to document transit agency clean power investments and purchases to better understand the scale of public transportation’s role as a zero­carbon–energy producer and consumer. Operational and infrastructure assessments should also include information on public transportation’s vulnerability to climate change and opportunities to harden assets to the increased flooding, fire, intense storms, and extreme heat we are now facing. Localizing Mode Shift Data The research presented here provides an assessment of the national GHG impacts of transit using best­practice GHG accounting techniques and activity data. The APTA data compilation used to calculate the mode shift factor is based on real­world passenger surveys and provides an up­to­date look at transportation options, including ridehailing. However, transit agencies would like more granular data of this type. Passenger surveys are time consuming and costly for smaller transit agencies. Using the national compilation of transit survey data along with place­based ridership and other travel information, such as from anonymized cell­phone data, it would be possible to build a national model of passenger mode shift preferences that

Conclusions and Suggested Research 35   would provide transit agencies more granular information on this issue. This would be valuable for GHG accounting reasons and could inform transit agency operations, partnerships, and investments. Further Unpacking Location Efficiency Impacts The transit multiplier modeling for this study presents a wealth of findings and opportu­ nities for further research. This could include a comparative look at model outputs in regions to better identify the causal forces of transit’s impacts on personal travel in the community; it is important to pay attention to causal effects on VMT, beyond correlation, when designing climate action. Land use patterns take time to develop, so the authors expect that areas with long­established transit and location­efficient land use patterns may see different impacts from areas with more recent changes. The authors also expect that regional variation may play a role. A more granular approach that looks at station­based ridership would be valuable but challenging to undertake on a national scale given the limits of existing ridership data (Pollack et al. 2015). Developing a method for mode­specific transit multipliers, though difficult to differentiate in areas with multiple modes overlapping spatially, would also be of use for transit service expansion decisions. Further unpacking transit’s location efficiency impacts would help shape climate action and target land use innovations that could help decarbonize communities while making them more transportation cost effective and healthy. Overall, in undertaking this research, the authors found a widespread interest in public transportation’s role as part of the essential infrastructure of communities addressing and responding to climate change. Continued research and action to identify and grow transit’s substantial climate benefits is of great importance to communities around the United States and the world.