Factors such as the economic recession, the rise of the on-demand economy, changes in the regulatory environment, population growth and urbanization have affected the distribution of goods. One example is the shift in the location of warehouses and distribution facilities away from consumer markets. This shift or logistics sprawl brings about unintended consequences such as increased vehicle miles traveled and concentration of freight activity in specific, usually disadvantaged, communities. In California, especially in Southern California, previous research showed an increase in the concentration of these facilities at longer distances from their primary delivery locations. Additional research also showed that while the trend exists in the region, it has not continued at the same pace in the last decade, or it may have even reversed. The 2008-2009 recession and the growth of e-commerce activity are two of the main factors that potentially explain this phenomenon. These changes are relevant for freight planning because they do not only affect the location of the facilities, but also traffic generation and potential changes in vehicles used. For example, smaller facilities closer to customer may use smaller vehicles distributing smaller shipments at higher frequencies; or, the redistribution of the freight activity and supply chain configurations.

This research brief summarizes findings from the project which used the California Department of Transportation Weigh-in-Motion data from stations located in Southern California from January 2003 to December 2015 to validate some of these assumptions.

Local governments have steadily increased their initiative to address global climate change, and many present their proposed strategies through climate action plans (CAPs). This study conducts a literature review on current local approaches to greenhouse gas (GHG) reduction strategies by assessing CAPs in California and presents common strategies in the transportation sector along with useful tools. One identified limitation of many CAPs is the omission of quantitative economic cost and emissions data for decision-making on the basis of cost-effectiveness. Therefore, this study proposes a framework for comparing strategies based on their life cycle emissions mitigation potential and costs. The results data can be presented in a marginal abatement cost curve (MACC) to allow for side-by-side comparison of considered strategies. Researchers partnered with Yolo and Unincorporated Los Angeles Counties to analyze 7 strategies in the transportation and energy sectors (five and two, respectively). A MACC was subsequently developed for each county. Applying the life cycle approach revealed strategies that had net cost savings over their life cycle, indicating there are opportunities for reducing emissions and costs. The MACC also revealed that some emissions reduction strategies in fact increased emissions on a life cycle basis. Applying the MACC framework to two case study jurisdictions illustrated both the feasibility and challenges of including quantitative analysis in their decision-making process. An additional barrier to using the MACC framework in the context of CAPs, is the mismatch between a life cycle and annual accounting basis for GHG emissions. Future work could explore more efficient data collection, alternative scopes of emissions for reporting, and environmental justice concerns.

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Local governments increasingly prepare Climate Action Plans to lay out specific strategies for achieving local and state greenhouse gas reduction goals. Strategies to reduce transportation emissions are often a key component of these plans, as the transportation sector is responsible for 41% of greenhouse gas emissions in California and 28% in the US. However, many Climate Action Plans do not quantify the emissions reductions or costs of proposed strategies, and even fewer consider the life cycle impacts of the strategies. Life cycle-based assessments consider emissions and costs that occur at the outset of a strategy’s implementation (e.g., purchase, installation, and construction), during operation and maintenance, and at end-of-life. Quantifying the life cycle cost effectiveness and emissions reductions of different strategies can, along with other community priorities, inform the design and implementation of Climate Action Plans that achieve climate goals at a reasonable cost. A marginal abatement cost curve is a useful way to present this information, offering a visualization of the rank order cost-effectiveness and total possible emissions reductions of alternative strategies in a Climate Action Plan.

Researchers at the University of California, Davis developed a decision support framework for local governments to assess life cycle greenhouse gas reductions and costs of Climate Action Plan strategies. The researchers demonstrated their approach by developing marginal abatement cost curves for two California counties, Yolo and Unincorporated Los Angeles, based on strategies from their respective Climate Action Plans. This policy brief summarizes findings from that research.

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The objective of this study was to develop a framework for determining the fuel use and environmental impacts caused by construction work zones (CWZs) on a range of vehicles and to produce initial calculations of these impacts by modeling traffic closure conditions for highway maintenance and rehabilitation (M&R) activities. The framework was developed and demonstrated in several scenarios. The study included three common highway categories—freeways, multi-lane highways, and two-lane highways—and common California vehicle types. The framework uses realistic drive cycle values and CWZ operation scenarios as inputs to the simulation software MOtor Vehicle Emission Simulator (MOVES) to estimate total fuel consumption and air pollutant emissions. In this study, the framework was demonstrated using three CWZ operations under different traffic congestion levels: light, medium, and heavy.

Fuel consumption and pollutant emissions results obtained for the CWZ operation scenario with and without congestion were compared with those for a no-CWZ, no-congestion scenario. In the simulation results for a freeway with a CWZ and heavy congestion, fuel consumption increased by 85% and the CO2 equivalent (CO2-e) emissions increased by 86%, NOx by 62%, SOx by 85%, and PM2.5 by 128%. In the multi-lane highway scenarios, fuel consumption increased by 85%, and CO2-e emissions increased by 88%, NOx by 75%, SOx by 87%, and PM2.5 emissions by 129% for a CWZ with heavy congestion. Lessening traffic congestion in a CWZ from heavy (average speed 5 mph) to medium (average speed 25 mph for a freeway section and 15 mph for a multi-lane road section) reduced fuel consumption by 40% on a freeway and 33% on multi-lane highway.

This study also included use of a pilot car in a CWZ on a two-lane road. This approach was undertaken to estimate the possible benefits of different CWZ lane closure strategies and traffic management plans. The pilot-car operation scenario results indicate that a one-lane closure with pilot-car operation on a two-lane road might consume 13% more fuel because of idling time and the slow movement of vehicles following the pilot car. This scenario generated emissions increases of 10% for CO2-e, 14% for NOx, 13% for SOx, and 65% for PM2.5.

The results of these scenarios indicate that the impacts from heavy vehicles far exceed those from smaller vehicles in CWZs. Phase 2 of the study will develop methods for pavement management, conceptual evaluation, and project design that consider construction closures by implementing this life cycle assessment framework. These methods will also be used in studies to evaluate pavement design lives (20 years versus 40 years) and pavement selection for truck lanes and in-place recycling and to evaluate lane closure schedules and tactics to minimize CWZ impacts on highways by using project-specific traffic congestion levels.