With potential for automobiles to cause increased greenhouse gas emissions and air pollution relative to other modes, there is concern that using automobiles to access or egress public transportation may significantly increase the environmental impacts from door-to-door transit trips. Yet little rigorous work has been developed that quantitatively assesses the effects of transit access or egress by automobiles. This research evaluates the life-cycle impacts of first-and-last mile trips on multimodal transit. An environmental life-cycle assessment of transit and automobile travel in the greater Los Angeles region is developed to evaluate the impacts of multimodal transit trips by utilizing existing transportation life-cycle assessment methods. First-last mile automobile trips with transit may increase multimodal trip emissions significantly, mitigating potential impact reductions from transit usage. In some cases, multimodal transit trips with first-last mile automobile use may have higher emissions than competing automobile trips. In the near-term, first-last mile automobile trips in some Los Angeles transit services may account for up to 66% of multimodal greenhouse gas trip emissions, and as much as 75% of multimodal air quality impacts. Fossil fuel energy generation and combustion, low vehicle occupancies, and longer trip distances contribute most to increased multimodal impacts. Supply chain analysis indicates that life-cycle air quality impacts may occur largely locally (in Los Angeles) or largely remotely depending on the propulsion method and location of upstream life-cycle processes. Reducing 10% of transit system greenhouse emissions requires a shift of 23–50% of automobile first-last mile trips to a neutral emissions mode.
Environmental and Economic Consequences of Permanent Roadway Infrastructure Commitment: City Road Network Life-cycle Assessment and Los Angeles CountyASCE Journal of Infrastructure Systems, 2016, 22(1), doi: 10.1061/(ASCE)IS.1943-555X.0000271
The environmental impacts and economic costs associated with passenger transportation are the result of complex interactions between people, infrastructure, urban form, and underlying activities. When it comes to roadway infrastructure, the ongoing resource commitments (which can be measured as embedded impacts) enables vehicle travel, which is a dominant source of air emissions in regional inventories. The relationship between infrastructure and the environmental impacts it enables are not often considered dynamic. Furthermore, the environmental effects of roadway infrastructure are typically assessed at a fine geospatial and temporal scale (i.e., a short distance of roadway over a short period of time) and there is generally poor knowledge of how the growth of a roadway network over time creates a need for long-term maintenance commitments that create environmental impacts and lock-in vehicle travel. A framework and operational lifecycle assessment (LCA) tool [City Road Network (CiRN) LCA] are developed to assess the extent to which roadway commitments result in ongoing and increasing environmental and economic impacts. Known for its extensive road network and automobile reliance, Los Angeles County is used as a case study to explore the relationship between historic infrastructure deployment decisions and the emergent behavior of vehicle travel. The results show that every kilogram of greenhouse gas (GHG) emissions resulting from construction and maintenance has led to 27 kg of GHG emissions in fuel combustion. Similarly, every public dollar invested into the network has created $21–$46 in private user spending. As states and regions grapple with financing the upkeep of aging infrastructure, a solid understanding of the relationship between upfront infrastructure capital costs, long-term maintenance costs, and associated long-term environmental effects are critical. In Los Angeles, the infrastructure that exists was largely deployed by 1987. Since then, maintenance costs are estimated to have exceeded city budgets despite minimal growth in infrastructure. The research demonstrates how infrastructure matures (i.e., its stages of growth toward completion), it becomes locked-in, leading to transitions from a capital financing focus to foci on securing rehabilitation and maintenance costs, and the share of environmental impacts changing from being somewhat balanced between embedded infrastructure construction impacts and vehicle use to today where vehicle use creates impacts several orders of magnitude greater than those associated with rehabilitation.
Time-based Life-cycle Assessment for Environmental Policymaking: Greenhouse Gas Reduction Goals and Public TransitTransportation Research Part D, 2016, 43, pp. 49-58, doi: 10.1016/j.trd.2015.12.003
As decision-makers increasingly embrace life-cycle assessment (LCA) and target transportation services for regional environmental goals, it becomes imperative that outcomes from changes to transportation infrastructure systems are accurately estimated. Greenhouse gas (GHG) reduction policies have created interest in better understanding how public transit systems reduce emissions. Yet the use of average emission factors (e.g., grams CO2e per distance traveled) persists as the state-of-the-art masking the variations in emissions across time, and confounding the ability to accurately estimate the environmental effects from changes to transit infrastructure and travel behavior. An LCA is developed of the Expo light rail line and a competing car trip (in Los Angeles, California) that includes vehicle, infrastructure, and energy production processes, in addition to propulsion. When results are normalized per passenger kilometer traveled (PKT), life-cycle processes increase energy use and GHG emissions up to 83%, and up to 690% for smog and respiratory impact potentials. However, the use of a time-independent PKT normalization obfuscates a decision-maker’s ability to understand whether the deployment of a transit system reduces emissions below a future year policy target (e.g., 80% of 1990 emissions by 2050). The year-by-year marginal effects of the decision to deploy the Expo line are developed including reductions in automobile travel. The time-based marginal results provide clearer explanations for how environmental effects in a region change and the critical life-cycle processes that should be targeted to achieve policy targets. It shows when environmental impacts payback and how much reduction is achieved by a policy-specified future year.
Parking Infrastructure: A Constraint on or Opportunity for Urban Redevelopment? A Study of Los Angeles County Parking Supply and GrowthJournal of the American Planning Association, 2015, 81(4), pp. 268-286 doi: 10.1080/01944363.2015.1092879
Many cities have adopted minimum parking requirements but we have relatively poor information about how parking infrastructure has grown. We estimate how parking has grown in Los Angeles County from 1900 to 2010 and how parking infrastructure evolves, affects urban form, and relates to changes in automobile travel, using building and roadway growth models. We find that since 1975 the ratio of residential offstreet parking spaces to automobiles in Los Angeles County is close to 1.0 and the greatest density of parking spaces is in the urban core while most new growth in parking occurs outside of the core. 14% of incorporated land in Los Angeles County is committed to parking. Uncertainty in our space inventory is attributed to our building growth model, onstreet space length, and the assumption that parking spaces were created as per the requirements. The continued use of minimum parking requirements is likely to encourage automobile use at a time when metropolitan areas are actively seeking to manage congestion and increase transit use, biking, and walking. Widely discussed ways to reform parking policies may be less than effective if planners do not consider the remaining incentives to auto use created by the existing parking infrastructure. Planners should encourage the conversion of existing parking facilities to alternative uses.
Cost-effectiveness of Reductions in Greenhouse Gas Emissions from High-speed Rail and Urban Transportation Projects in CaliforniaTransportation Research Part D, 2015, 40, pp. 104-113, doi: 10.1016/j.trd.2015.08.008
As California establishes its greenhouse gas emissions cap-and-trade program and considers options for using the new revenues produced under the program, the public and decision-makers have access to tenuous information on the relative cost-effectiveness of passenger transportation investment options. Towards closing this knowledge gap, the cost-effectiveness of greenhouse gas reductions forecast from High-Speed Rail are compared with those estimated from recent urban transportation projects (specifically light rail, bus rapid transit, and a bicycling/pedestrian pathway) in California. Life-cycle greenhouse gas emissions are joined with full cost accounting to better understand the benefits of cap-and-trade investments. Results are largely dependent on the economic cost allocation method used. Considering only public subsidy for capital, none of the projects appear to be a cost-effective means to reduce greenhouse gas emissions (i.e., relative to the current price of greenhouse gas emissions in California’s cap-and-trade program at $11.50 per tonne). However, after adjusting for the change in private costs users incur when switching from the counterfactual mode (automobile or aircraft) to the mode enabled by the project, all investments appear to reduce greenhouse gas emissions at a net savings to the public. Policy and decision-makers who consider only the capital cost of new transportation projects can be expected to incorrectly assess alternatives and indirect benefits (i.e., how travelers adapt to the new mass transit alternative) should be included in decision-making processes.
Policymaking Should Consider the Time-dependent Greenhouse Gas Benefits of Transit-oriented Smart GrowthTransportation Research Record, 2015, 2502, pp. 53-61, doi: 10.3141/2502-07
Cities are developing greenhouse gas (GHG) mitigation plans and reduction targets on the basis of a growing body of knowledge about climate change risks, and changes to passenger transportation are often at the center of these efforts. Yet little information exists for characterizing how quickly or slowly GHG emissions reductions will accrue given changes in urban form around transit and whether benefits will accrue quickly enough to meet policy year targets (such as reaching 20% of 1990 GHG emissions levels by 2050). Achieving GHG reductions through integrated transportation and land use planning is even more complicated for cities because changes in emissions can occur across many sectors (such as transportation, building energy use, and electricity generation). With the use of the Los Angeles, California, Expo Line, a framework was developed to assess how financing schemes could affect the rate of building redevelopment and resulting life-cycle GHG emissions from travel and building energy use. The framework leveraged an integrated transportation and land use life-cycle assessment model that captured upfront construction of new development near transit and the long-term changes in household energy use for travel and buildings. The results show that for the same amount of development around the Expo Line, it is possible either to meet state GHG goals by 2050 (if aggressive redevelopment happens early) or not meet those goals by 2050 (if significant redevelopment does not start for decades). The time-based approach reveals how redevelopment schedules should be considered when strategies for meeting future GHG emissions targets are set.
Recent climatic trends show more flooding and extreme heat events and in the future transportation infrastructure may be susceptible to more frequent and intense environmental perturbations. Our transportation systems have largely been designed to withstand historical weather events, for example, floods that occur at an intensity that is experience once every 100 years, and there is evidence that these events are expected become more frequent. There are increasing efforts to better understand the impacts of climate change on transportation infrastructure. An abundance of new research is emerging to study various aspects of climate change on transportation systems. Much of this research is focused on roadway networks and reliable automobile travel. We explore how flooding and extreme heat might impact passenger rail systems in the Northeast and Southwest U.S..
Transit-oriented Smart Growth Can Reduce Life-cycle Environmental Impacts and Household Costs in Los AngelesTransport Policy, 2014, 35, pp.21-30, doi: 10.1016/j.tranpol.2014.05.004
The environmental and economic assessment of neighborhood-scale transit-oriented urban form changes should include initial construction impacts through long-term use to fully understand the benefits and costs of smart growth policies. The long-term impacts of moving people closer to transit require the coupling of behavioral forecasting with environmental assessment. Using new light rail and bus rapid transit in Los Angeles, California as a case study, a life-cycle environmental and economic assessment is developed to assess the potential range of impacts resulting from mixed-use infill development. An integrated transportation and land use life-cycle assessment framework is developed to estimate energy consumption, air emissions, and economic (public, developer, and user) costs. Residential and commercial buildings, automobile travel, and transit operation changes are included and a 60-year forecast is developed that compares transit-oriented growth against growth in areas without close access to high-capacity transit service. The results show that commercial developments create the greatest potential for impact reductions followed by residential commute shifts to transit, both of which may be effected by access to high-capacity transit, reduced parking requirements, and developer incentives. Greenhouse gas emission reductions up to 470 Gg CO2-equivalents per year can be achieved with potential costs savings for TOD users. The potential for respiratory impacts (PM10-equivalents) and smog formation can be reduced by 28–35%. The shift from business-as-usual growth to transit-oriented development can decrease user costs by $3100 per household per year over the building lifetime, despite higher rental costs within the mixed-use development.
We model the deployment of roadway infrastructure in Los Angeles County. Presented below is an animation of the deployment of the Los Angeles Roadway network, from 1990 to present. The work is published: A Fraser and M Chester, Environmental and Economic Consequences of Permanent Roadway Infrastructure Commitment: City Road Network Life-cycle Assessment and Los Angeles County, ASCE Journal of Infrastructure Systems, 2016, 22(1), doi: 10.1061/(ASCE)IS.1943-555X.0000271.
Infrastructure and Automobile Shifts: Positioning Transit to Reduce Life-cycle Environmental Impacts for Urban Sustainability GoalsEnvironmental Research Letters, 2013, 8(1), 015041, doi: 10.1088/1748-9326/8/1/015041
Public transportation systems are often part of strategies to reduce urban environmental impacts from passenger transportation yet comprehensive energy and environmental life-cycle measures, including upfront infrastructure effects and indirect and supply chain processes, are rarely considered. Using the new bus rapid transit and light rail lines in Los Angeles, near-term and long-term life-cycle impact assessments are developed, including reduced automobile travel. Energy consumption and emissions of greenhouse gases and criteria pollutants are assessed, as well the potential for smog and respiratory impacts. Results show that life-cycle infrastructure, vehicle, and energy production components significantly increase the footprint of each mode (by 48-100% for energy and greenhouse gases, and up to 6200% for environmental impacts), and emerging technologies and renewable electricity standards will significantly reduce impacts. Life-cycle results are identified as either local (in Los Angeles) or remote and show how the decision to build and operate a transit system in a city produces environmental impacts far outside of geopolitical boundaries. Ensuring shifts of between 20-30% of transit riders from automobiles will result in passenger transportation greenhouse gas reductions for the city, and the larger the shift the quicker the payback, which should be considered for time-specific environmental goals.