Frank Gallivan

Structural equation models of VMT growth in US urbanised areas

Vehicle miles travelled (VMT) is a primary performance indicator for land use and transportation, bringing with it both positive and negative externalities. This study updates and refines previous work on VMT in urbanised areas, using recent data, additional metrics and structural equation modelling (SEM). In a cross-sectional model for 2010, population, income and freeway capacity are positively related to VMT, while gasoline prices, development density and transit service levels are negatively related. Findings of the cross-sectional model are generally confirmed in a more tightly controlled longitudinal study of changes in VMT between 2000 and 2010, the first model of its kind. The cross-sectional and longitudinal models together, plus the transportation literature generally, give us a basis for generalising across studies to arrive at elasticity values of VMT with respect to different urban variables.

Planning for Impacts of Climate Change at U.S. Ports

U.S. ports need to better understand climate change and how it may affect them. In the coming decades, ports are likely to experience higher sea levels and storm surges, as well as other direct and indirect impacts, due to climate change. Most ports do not appear to be thinking about, let alone actively preparing to address, the effects of climate change. Ports do not have specific information about either the types of impacts that they can expect on their facilities or the probabilities of different types of impacts occurring. Although climate change science is making considerable advances, projections of impacts at levels smaller than the regional scale are not available. In addition, ports’ typical planning processes are ill equipped to respond to the high levels of uncertainty associated with the impacts of climate change, the timescales of climate change, and the geographical scale of climate change. The data that ports typically use for planning purposes do not incorporate climate change forecasts. Some ports also believe that climate change does not pose an immediate threat to their facilities. However, several ports are beginning to think about how to prepare for climate change. These include the Port of Miami (Miami, Florida), the Port Authority of New York and New Jersey, the Massachusetts Port Authority, the Port of Seattle (Seattle, Washington), the Port of Corpus Christi (Corpus Christi, Texas), and the Georgia Ports Authority. To help these and other ports assess their risk, more and better data are needed, as well as better planning tools and methods.

Integrating Climate Change into State and Regional Transportation Plans

This paper aims to advance the practice and application of transportation planning for state, regional, and local transportation planning agencies to address the relationship between transportation and climate change. The focus of the paper is on long-range planning documents as tools for climate change planning. Reviews included federal regulations and statutes that govern transportation planning as well as a sample of current planning documents from state departments of transportation (DOTs) and metropolitan planning organizations (MPOs). Interviews were conducted with four DOTs and eight MPOs that were incorporating climate change into long-range transportation plans. The text of federal statutes provides opportunities to link climate change considerations with transportation planning. The current practice in transportation plans varies widely by agency. Climate change can appear in the vision, goals, policies, strategies, trends and challenges, and performance measures of planning documents. Some plans merely recognize that climate change is related to transportation and begin to relate existing plans and strategies to climate change. Other plans make climate change more central to their goals and policies. Some agencies are quantifying greenhouse gas emissions related to transportation plans and programs. Quantification will likely be a key component of plans in the future. Research highlighted several types of barriers and needs for agencies considering climate change in transportation plans. These barriers were reviewed. Some simple recommendations were provided for how state DOTs and MPOs could address them.

Combined Effects of Compact Development, Transportation Investments, and Road User Pricing on Vehicle Miles Traveled in Urbanized Areas

Vehicle miles traveled (VMT) is the primary determinant of traffic congestion, vehicle crashes, greenhouse gas emissions, and other effects of transportation. Two previous studies have sought to explain VMT levels in urbanized areas. This study updates and expands on previous work with more recent data, additional metrics, and structural equation modeling (SEM) to explain VMT levels in 315 urbanized areas. According to SEM, population, income, and gasoline prices are primary exogenous drivers of VMT. Development density is a primary endogenous driver. Urbanized areas with more freeway capacity are significantly less dense and have significantly higher VMT per capita. Areas with more transit service coverage and service frequency have higher development densities and per capita transit use, which leads to lower VMT per capita. The indirect effect of transit on VMT through land use, the so-called land use multiplier, is more than three times greater than the direct effect through transit ridership.

Cost-Effective Approaches to Reduce Greenhouse Gas Emissions Through Public Transportation in Los Angeles, California

The Los Angeles County, California, Metropolitan Transportation Authority (Metro) commissioned a study of strategic options for the agency to reduce greenhouse gas (GHG) emissions. This study compared a comprehensive range of strategies on potential GHG reductions and cost-effectiveness, in dollars per ton of GHG emissions reduced. Sixteen strategies were analyzed in four categories: promotion of alternative travel modes, transit service, vehicle technology, and facility energy use. Strategies with the greatest potential for GHG emission reductions (regardless of cost) included transit-oriented development, vanpool subsidy, onboard railcar energy storage, and ridesharing and transit programs for employers. The first three would save or generate money for Metro. Ridesharing and transit programs have the potential for net revenue generation, but the results were uncertain. Four more strategies would reduce smaller amounts of emissions while also saving money for the agency: recycled water for bus washing, low-water sanitary fixtures, Red Line tunnel lighting retrofits, and facility lighting efficiency. Understanding opportunities for GHG reductions requires expertise in transit operations, vehicles, facilities, and planning. Cost-effectiveness and total reduction potential can be supporting criteria in making funding decisions. The largest GHG reduction opportunities for Metro are typically those that reduce vehicle miles traveled, whereas many of the most cost-effective strategies address GHG emissions from facility energy use. Cost-effectiveness of a strategy to Metro can depend greatly on receipt of external funding, including federal funds or utility rebates. In some cases, the range of cost-effectiveness for a strategy is so great that it is not useful to inform decision making without some further definition.

Quantifying Transit’s Impact on GHG Emissions and Energy Use—The Land Use Component

This report analytically examines the complex interrelationships between transit and land use patterns to better understand their contribution to compact development and the resulting greenhouse gas (GHG) reduction benefits. The report is accompanied by an Excel-based sketch-modeling tool (“calculator tool”) that applies the research findings. The calculator tool estimates the land use benefits of existing or planned transit projects with a minimum amount of input data required. The report presents transit’s impact on GHG emissions and energy use, including both the ridership effects and the land use effects; introduces and provides a user’s guide to the calculator tool; identifies future research; and includes two technical appendices pertaining to the use of statistical models in this research. This research will be useful to transit agencies, planners, modelers, and researchers seeking to better understand and to quantify the impacts of transit service on compact development, energy use, and air quality in urbanized areas.

Inclusion of Regional Transit Emissions in Local Greenhouse Gas Inventories: Comparison of Methods with Examples from Portland, Oregon, and San Francisco Bay Area, California

Methods to attribute greenhouse gas emissions from transit vehicles across cities in a multijurisdictional region are explored. Four methods and one submethod are proposed, tested, and evaluated with real-world data from the Bay Area Rapid Transit District, serving the San Francisco Bay Area, California, and the Tri-County Metropolitan Transportation District of Oregon, serving the Portland area. Each methodology is evaluated on the basis of the likely availability of necessary data, ease of calculation, policy implications, and accuracy. Method 1 allocates emissions on the basis of each jurisdictions total population and employment as a share of population and employment from all of the regions jurisdictions that have transit access. Method 2 allocates emissions on the basis of each jurisdictions share of vehicle revenue miles traveled within the jurisdiction. Method 3 allocates emissions on the basis of each jurisdictions share of linked transit trip origins and destinations weighted by trip distances. Method 4 allocates emissions on the basis of each jurisdictions share of boardings and alightings. The methods have clear differences in the amount and type of data and the complexity of calculations required. These differences can be readily compared with the data and analytical resources available to a region to provide a partial ranking of methods. Questions of fairness, accuracy, and policy incentives are complicated by theoretical challenges in assigning responsibility for transit service as well as by the unique urban and transportation contexts of each region. Each region will need to select the method that is most appropriate for its unique circumstances in order to achieve intraregional consistency.

Toward a Better State Climate Action Plan: Review and Assessment of Proposed Transportation Strategies

A major body of transportation greenhouse gas (GHG) reduction strategies is contained in state-level climate action plans (CAPs). There has been some concern among major stakeholder groups that CAPs are not rigorously developed documents and that the reductions estimated in CAPs are unrealistic given real constraints on funding and implementation authority. This paper analyzes a subset of 84 strategies in nine states’ CAPs to determine how reliable reduction estimates are and where significant sources of uncertainty arise. Measures from these CAPs are evaluated according to requirements for enactment, external factors that play a role in implementation, quantification methods, and variables used in the quantification. For enactment of strategies, nearly all of the transportation GHG reductions estimated in state CAPs would require new state legislation or state agency rulemaking. Half of the reductions would require major new funding. For implementation factors, one-third of state CAP GHG reductions relies heavily on assumptions about the future price of transportation. A relatively small portion (10%) of the estimated GHG reductions depends on changes in land use. Some of the greatest uncertainty stems from strategies that are quantified with goals rather than empirical data and are not supported by a feasibility study. The authors judge that if state CAP transportation strategies are enacted as stated, roughly one-third of the estimated reductions in GHG emissions is highly uncertain. As states develop and revise CAPs in the future, they can focus on developing and quantifying strategies in a way that increases the likelihood that strategies will achieve at least the reductions estimated.