Transit-oriented smart growth can reduce life-cycle environmental impacts and household costs in Los Angeles

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

Policy Making Should Consider Time-Dependent Greenhouse Gas Benefits of Transit-Oriented Smart Growth

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

Integrating Life-cycle Environmental and Economic Assessment with Transportation and Land Use Planning

The environmental outcomes of urban form changes should couple life-cycle and behavioral assessment methods to better understand urban sustainability policy outcomes. Using Phoenix, Arizona light rail as a case study, an integrated transportation and land use life-cycle assessment (ITLU-LCA) framework is developed to assess the changes to energy consumption and air emissions from transit-oriented neighborhood designs. Residential travel, commercial travel, and building energy use are included and the framework integrates household behavior change assessment to explore the environmental and economic outcomes of policies that affect infrastructure. The results show that upfront environmental and economic investments are needed (through more energy-intense building materials for high-density structures) to produce long run benefits in reduced building energy use and automobile travel. The annualized life-cycle benefits of transit-oriented developments in Phoenix can range from 1.7 to 230 Gg CO₂e depending on the aggressiveness of residential density. Midpoint impact stressors for respiratory effects and photochemical smog formation are also assessed and can be reduced by 1.2–170 Mg PM₁₀e and 41–5200 Mg O₃e annually. These benefits will come at an additional construction cost of up to $410 million resulting in a cost of avoided CO₂e at$16–29 and household cost savings