Achieving Goals of San Francisco, California, for Greenhouse Gas Reductions in Transportation Sector: What Would It Take?

Although several studies analyze strategies for reducing transportation's contribution to greenhouse gas (GHG) emissions, few do so at the local level, particularly for a city such as San Francisco, California, that is already a leader in climate-friendly transportation. This study examined nine GHG-reducing strategies within the San Francisco context, where local ordinance establishes a goal to reduce the city's GHGs 80% below 1990 levels by 2050. Strategies that were analyzed included infrastructure improvements, expansion of demand management policies including pricing, and accelerated penetration of electric vehicle technology. The study used a combination of travel demand model and sketch-planning methods to estimate the effectiveness and cost-effectiveness of strategies in reducing GHGs and their cumulative ability to achieve San Francisco's goal. The analysis results showed roadway pricing and electric vehicle strategies to have had the largest potential to reduce GHGs, although these two strategies differed significantly in cost-effectiveness. The results also showed that strategies involving share costs between public sector, private sector, and individuals had great promise in delivering reductions. Although investments in transit alone may not produce large GHG reductions, they are necessary to accommodate the mode shift of other strategies and can be paired strategically with pricing strategies. According to analysis results, San Francisco's policy goals appeared unachievable, even with ambitious assumptions about funding and policy change. These findings point to the need for policy change at a higher scale and for unprecedented changes in individual behavior to achieve GHG goals.