No abstract
More than 11 million Americans reside within 150 meters of a highway, an area of high air pollution exposure. Traffic congestion further contributes to environmental pollution (e.g., air and noise), but its unique importance for population health is unclear. We hypothesized that degraded environmental quality specifically from traffic congestion has harmful impacts on fetal growth. Using a population-based cohort of births in Texas (2015–2016), we leveraged connected vehicle data to calculate traffic congestion metrics around each maternal address at delivery. Among 579,122 births, we found consistent adverse associations between traffic congestion and reduced term birth weight (8.9 grams), even after accounting for sociodemographic characteristics, typical traffic volume, and diverse environmental coexposures. We estimated that up to 1.2 million pregnancies annually may be exposed to traffic congestion (27% of births in the United States), with ~256,000 in the highest congestion zones. Therefore, improvements to traffic congestion may yield positive cobenefits for infant health.
The U.S. Army Corps of Engineers (USACE) is responsible for the maintenance of federally authorized navigation channels and associated infrastructure. As such, USACE requires objective performance measures for determining the level of service being provided by the hundreds of maintained navigation projects nationwide. To this end, the U.S. Army Engineer Research and Development Center partnered with Texas A&M Transportation Institute to develop a freight fluidity assessment framework for coastal ports. The goal was to use archival automatic identification system (AIS) data to develop and demonstrate how ports can be objectively compared in relation to fluidity, or the turnaround time reliability of oceangoing vessels. The framework allows USACE to evaluate maintained navigation project conditions alongside port system performance indices, thereby providing insight into questions of required maintained channel dimensions. The freight fluidity concept focuses on supply chain performance measures such as travel time reliability and end-to-end shipping costs. Although there are numerous research efforts underway to implement freight fluidity, this is the first known application to U.S. ports. This paper covers AIS data inputs, quality control, and performance measures development, and also provides a demonstration application of the methodology at the Port of Mobile, Alabama, highlighting travel time and travel time reliability operating statistics for the overall port area. This work provides foundational knowledge to practitioners and port stakeholders looking to improve supply chain performance and is also valuable for researchers interested in the development and application of multimodal freight fluidity performance measures.
For more than 30 years, the Texas A&M Transportation Institute (TTI) has developed methodologies and appropriate performance measures for estimating congestion performance and communicating them to technical and nontechnical audiences. TTI's Urban Mobility Report (UMR) has historically focused on passenger car congestion (i.e., congestion caused by the average commuter). However, roadway traffic congestion certainly affects both commuters and goods movement. With the documented growth of freight shipments and value, particularly in trucking, researchers developed and applied a methodology to include in UMR the truck freight commodity value that is affected by congestion in urban areas. The methodology uses data from FHWA's Freight Analysis Framework (FAF) and Highway Performance Monitoring System (HPMS). Commodity values supplied by the FAF are integrated into truck vehicle miles of travel calculated from the HPMS roadway inventory. Researchers estimated that $7 trillion worth of commodities were trucked on America's urban streets and highways during 2010. At the urban-area level, the results of the truck value measure appear to be intuitive, as bigger cities consume more goods and the greater consumption means a higher value of freight movement. The addition of a truck value to the UMR provides another dimension to inform policy makers and decision makers about the congestion problem. This addition also serves to inform trucking stakeholders with an estimate of the amount of truck value that is affected by congestion. Researchers will continue to include the truck freight value performance measure in subsequent releases of the UMR.
Few analytical techniques fully incorporate freight aspects into transportation system monitoring, system evaluation, and project selection. Transportation investment decisions are frequently based on typical performance measures of travel time and delay for passenger travel, and little, if any, attempt is made to incorporate goods movement into such analysis. Research was performed by the Texas Transportation Institute for a better understanding of freight mobility and reliability issues. The research developed a conceptual framework to help transportation professionals communicate, visualize, and understand factors affecting freight mobility and reliability; a methodology with which to estimate congestion for the conceptual framework; and two applications of the methodology to truck freight (one in Austin, Texas, and one in Denver, Colorado). The conceptual framework visually incorporates the effects of geographic area, commodity type, and time period on freight mobility and reliability. This framework provides a method to communicate freight congestion, mobility, and reliability and can be expanded to include all freight modes (truck, rail, maritime, air, and pipeline). The conceptual framework and methodology can help transportation professionals to better communicate, understand, and make planning-level decisions based on the factors that affect freight mobility and reliability.
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