The technique of hydraulic fracturing (also known as fracking) has been widely used to increase domestic oil and gas production in the United States. The process involves injecting a water solution deep into the bedrock formation using a well. Pressure from the water creates cracks in the shale rock formations and creates oil and/or gas flow from the formation [USGS 2016]. The hydraulic fracturing process has existed since around 1949, but only since the 1990s has it gained national attention as various energy companies began utilizing it to produce gas/oil in commercial quantities. In 2015 hydraulic fracturing accounted for more than half of U.S. domestic crude oil production. From 2000 to 2015, the number of hydraulically fractured wells in the United States increased from about 23,000 to around 300,000 [USDOE EIA 2016d].

Hydraulic fracturing has altered patterns of domestic energy transportation by expanding oil and gas production in many areas, including those that do not have pipelines in place to deliver the oil to refineries. According to the Energy Information Administration (EIA), crude oil movement by rail has shown large increases over the past 5 years, with much of the growth stemming from oil being transported from the upper Midwest to the Gulf of Mexico and northeast for processing [USDOE EIA 2016c].

Oil production requires significant transportation inputs, such as the transport of well development equipment and supplies by truck as well as the transport of the crude oil from well fields to refineries via pipelines and/or rail or barge. Well development requires thousands of gallons of water and chemicals resulting in high volumes of truck traffic that far exceed the design and capacity of local roads while potentially creating a safety hazard for local drivers [NPHL 2011]. Each well requires 2,300 drilling-related truck movements [UGPTI 2014]. Once the well goes into production mode, trucks may again be used to transport the oil from the well to a pipeline, barges, or rail cars for transport to a processing facility.