Information on Data Sources
Information on Data Sources
Airline freight and passenger data
The U.S. Department of Transportation's (USDOT), Research and Innovative Technology Administration (RITA), Bureau of Transportation Statistics (BTS) collects and compiles data on the volume of revenue passengers, freight, and mail traffic handled and reported by the nation's large certificated air carriers. These carriers hold Certificates of Public Convenience and Necessity (CPCN) issued by the USDOT authorizing the performance of air transportation. Large certificated air carriers operate aircraft with seating capacity of more than 60 seats or a maximum payload capacity of more than 18,000 pounds or conduct international operations. Data for commuters, intrastate, nonscheduled air taxi operators, and foreign flag air carriers are not included.
Contact: USDOT, RITA, Bureau of Transportation Statistics, Office of Airline Information
Commodity Flow Survey
The Commodity Flow Survey (CFS) provides data on the movement of freight by type of commodity shipped and by mode of transport. In 2007, approximately 100,000 domestic establishments were randomly selected from a universe of approximately 750,000 engaged in mining, manufacturing, wholesale trade, warehouses and managing offices of multi-establishment companies, and some selected activities in retail and services based on the 2002 NAICS classification system. The survey excluded establishments classified as farms, forestry, fisheries, governments, construction, transportation, foreign establishments, and most services and retail trade establishments. For the 2007 CFS, each selected establishment reported on average about 25 of its outbound shipments for a one-week period in each of four calendar quarters in 2007. This produced a total sample of over 2.4 million shipments. Due to industry-wide reporting problems, shipments by oil and gas extraction establishments were excluded from data tabulations.
For each sampled 2007 CFS shipment, zip code of origin and destination, 5-digit Standard Classification of Transported Goods (SCTG) code, weight, value, and modes of transport were provided. Information on whether the shipment was a hazardous material or an export was also obtained. The miles traveled by each shipment was determined using the shipment information reported by the respondents, and a software tool, called GeoMiler, that has been developed by the Bureau of Transportation Statistics (BTS) in partnership with MacroSys Research and Technology (MacroSys) for estimating freight travel. Distance was used to compute ton-mileage by mode of transport. The 2007 CFS also provides nationwide geographic coverage and in-state and selected sub-state areas.
Contact: USDOT, RITA, Bureau of Transportation Statistics
Print source: USDOT, RITA, Bureau of Transportation Statistics and U.S. Department of Commerce (USDOC), U.S. Census Bureau, 2007 Commodity Flow Survey (Washington, DC: 2009).
Commuting data are from the American Community Survey (ACS), a nationwide Census Bureau survey designed to replace the long form in the decennial census. Instead of collecting data every ten years, the data collection occurs continuously. The ACS uses a series of monthly samples to produce annually updated data. This survey has an annual sample of three million housing units and will provide estimates of demographic, housing, social, and economic characteristics every year for states, cities, counties, metropolitan areas, and other geographic areas. Data products based on twelve-month periods are already available for geographic areas of 65,000 and greater population. Data products based on thirty-six-month periods are available starting in 2008 for geographic areas of 20,000 and greater population. Data products based on sixty-month periods are available as of 2010 for all geographic areas. Once the data products based on sample periods of more than twelve months are released for the first time, they will be released annually thereafter.
Contact: USDOC, U.S. Census Bureau
Gas and hazardous liquid pipeline data
Fatality and injury data for natural gas pipelines and hazardous liquid pipelines are based on reports filed with the USDOT, Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety under 49 CFR 191 and 49 CFR 195. Accidents must be reported as soon as possible, but no later than 30 days after discovery. Undetected releases are a possible source of error; even if subsequently detected and reported, it may not be possible to accurately reconstruct the accident. Property damage figures are estimates.
Gas pipeline incidents involve: 1) releases of gas from a pipeline or liquefied natural gas (LNG) or gas from an LNG facility that results in a) death or personal injury necessitating in-patient hospitalization, or b) estimated property damage, including cost of gas lost, of the operator or others, or both, of $50,000 or more; 2) an event that results in an emergency shutdown of an LNG facility; or 3) an event that is significant, in the judgment of the operator, even though it did not meet the criteria of 1) or 2).
For hazardous liquid pipelines, an accident report is required for each failure in a pipeline system in which there is a release of the hazardous liquid or carbon dioxide transported resulting in any of the following: 1) explosion or fire not intentionally set by the operator; 2) loss of 50 or more gallons of hazardous liquid or carbon dioxide; 3) release to the atmosphere of more than 5 barrels (0.8 cubic meters) per day of highly volatile liquids; 4) death of any person; 5) bodily harm to any person resulting in one or more of the following: a) loss of consciousness, b) an individual being carried from the scene, c) medical treatment, or d) disability that prevents the discharge of normal duties or the pursuit of normal activities beyond the day of the accident; or 6) estimated property damage, including cost of clean-up and recovery, value of lost product, and damage to the property of the operator or others, or both, exceeding $50,000.
Contact: USDOT, Pipeline and Hazardous Materials Safety Administration, Office of Pipeline Safety
Government transportation revenue and expenditure data
The U.S. Department of Commerce, U.S. Census Bureau conducts an Annual Survey of Government Finances. Alternatively, every five years, in years ending in a '2or '7, a Census of Governments, including a finance portion, is conducted. The survey coverage includes all state and local governments in the United States. For both the census and annual survey, the finance detail data encompass revenue, expenditure, debt, and assets. These data are the primary source of state and local government data used by BTS to produce Government Transportation Financial Statistics.
The data collection for the annual survey by the U.S. Census Bureau uses two methods: mail canvas and central collection from state sources. Data for local governments include counties, municipal, townships, special districts, and school districts. Data for state governments are compiled from state government audits, budgets, and other financial reports into the classification categories used for reporting by the Census Bureau.
Reporting of government finances by the Census Bureau involves presentation of data in uniform categories. While often similar to, or identical to, the classification used by the state or local government, there could be instances in which a significant difference exists between the name used by a state for a financial item and the final category to which it is assigned by the Census Bureau.
Like financial transactions are combined. The financial categories for revenue involve grouping of items by source. Revenue items of the same kind are merged. Financial transactions for expenditures are classified both by function and by object category. Debt items are classified by term (short and long term), as well as by type of debt and, to a limited extent, by purpose. Assets also are put into uniform categories, grouped by type of holding, with holdings for insurance trust systems grouped separately from general government.
The share of government sector financial totals contributed by a state government or by local governments differs materially from one state to another. Users can review the Government Finance and Employment Classification Manual for additional information regarding the financial categories. The financial amounts in the tables and files are statistical in nature and do not represent accounting statements or conditions.
The local government statistics are developed from a sample survey. Therefore, the local totals, as well as state and local aggregates, are considered estimated amounts subject to sampling error. State government finance data are not subject to sampling. Consequently, state-local aggregates for individual states are more reliable (on a relative standard error basis) than the local government estimates they include.
Contact: USDOC, U.S. Census Bureau, Finance Branch; or USDOT, RITA Bureau of Transportation Statistics.
Hazardous materials incidents data
Incidents resulting in certain unintentional releases of hazardous materials must be reported under 49 CFR 171.16. Each carrier must submit a report to the USDOT, Pipeline and Hazardous Materials Safety Administration (PHMSA) within 30 days of the incident, including information on the mode of transportation involved, results of the incident, and a narrative description of the accident. These reports are generally made available on PHMSA's incident database within 90 days of receipt.
Fatalities and injuries are counted only if directly caused by a hazardous material. For example, a truck operator killed by impact forces during a motor vehicle crash would not be counted as a hazardous-material fatality. PHMSA contacts the submitting carrier by telephone to verify all reported fatalities.
Although PHMSA acknowledges there is some level of underreporting, it believes the underreporting is mostly limited to small, nonserious incidents. The reporting requirements were extended to intrastate highway carriers on Oct. 1, 1998. Property damage figures are estimates determined by the carrier prior to the 30-day reporting deadline and are generally not subsequently updated. Property damage figures, therefore, may underestimate actual damages.
Contact: USDOT, Pipeline and Hazardous Materials Safety Administration, Office of Hazardous Materials Planning and Analysis
Highway mileage, condition, usage, driver license, and highway vehicle registration data
Data on roadway mileage, condition, and use are extracted from the Highway Performance Monitoring System (HPMS), which uses a stratified simple random sample of highway links (small sections of roadway) selected from state inventory files. The HPMS sample was designed as a fixed sample to minimize data-collection costs, but adjustments to maintain adequate representation are carried out periodically. The HPMS also consists of universe reporting (a complete census) for the Interstate and the National Highway System, and tabular summary reporting of limited information.
Data are collected independently by the states, metropolitan planning organizations (MPOs), and other local jurisdictions. Many of the geometric data items (e.g., number of lanes) change slowly, while other data items (e.g., traffic volumes) are more dynamic over time. The U.S. Department of Transportation, Federal Highway Administration (FHWA) provides guidelines for data collection in the HPMS Field Manual, which the states follow to varying extents, depending on factors such as staff, resources, state perspective, uses of the data, and state/MPO/local needs for the data. State Departments of Transportation (DOTs) report HPMS data annually to FHWA.
HPMS data are subject to sampling and nonsampling error. Nonsampling error is the major concern with these data. For some of the most variable and important data items, such as traffic, guidelines for measurement and data collection have been produced. States have the option of using the guidelines or using their own procedures. Many data items are difficult and costly to collect and are reported as estimates not based on direct measurement. The data are collected and reported by many entities within the responsible organizations.
States provide vehicle registration data to FHWA. Vehicle registration data are shown on a calendar year basis. Efforts are made to exclude transfers, re-registrations, and any other factors that could result in duplication in the vehicle counts. Registration practices for commercial vehicles differ greatly among the states. Some states register a tractor-semitrailer combination as a single unit; others register the tractor and the semitrailer separately. Some states register buses with trucks or automobiles, while many states do not report house and light utility trailers separately from commercial trailers or semitrailers. Some states do not require registration of car or light utility trailers. In some instances, FHWA has supplemented the data supplied by the states with information obtained from other sources.
States also provide driver licensing data to FHWA. Although efforts are made to minimize license duplication, drivers who move from one state to another are sometimes counted in both states until the license from the previous state of residence expires. Problems with the data also arise because: 1) some individuals obtain their drivers licenses in states other than those of legal residence; 2) some individuals fraudulently obtain multiple licenses; 3) not all individuals who drive are licensed; and 4) the purging of expired licenses or licenses from deceased individuals is not performed on a continual basis.
Contact: USDOT, Federal Highway Administration, Office of Highway Policy Information
Print source: USDOT, Federal Highway Administration, Highway Statistics (Washington, DC: Annual Issues).
Highway safety data
Fatalities: Highway fatality data are extracted from the Fatality Analysis Reporting System (FARS), which is compiled by USDOT National Highway Traffic Safety Administration (NHTSA). Data are gathered from a census of police accident reports (PARs), state vehicle registration files, state drivers licensing files, state highway department data, vital statistics, death certificates, coroner/medical examiner reports, hospital medical reports, and emergency medical service reports. A separate form is completed for each fatal crash. Blood alcohol concentration (BAC) is estimated when not known. Statistical procedures used for unknown data in the FARS can be found in the NHTSA report, A Method for Estimating Posterior BAC Distributions for Persons Involved in Fatal Traffic Accidents, DOT HS 807 094 (Washington, DC: July 1986).
Data are collected from relevant state agencies and electronically submitted for inclusion in the FARs database on a continuous basis. Cross-verification of PARs with death certificates helps prevent undercounting. Moreover, when data are entered, they are checked automatically for acceptable range values and consistency, enabling quick corrections when necessary. Several programs continually monitor the data for completeness and accuracy. Periodically, sample cases are analyzed for accuracy and consistency.
FARS data do not include motor vehicle fatalities on nonpublic roads. These are thought to account for about 2 percent or fewer of the total motor vehicle fatalities per year.
Injuries and crashes: NHTSA's General Estimates System (GES) data are a nationally representative sample of police-reported crashes that contributed to an injury or fatality or resulted in property damage and involved at least one motor vehicle traveling on a traffic way. GES data collectors randomly sample PARs and forward copies to a central contractor for coding into a standard GES system format. Documents such as police diagrams or supporting text provided by the officers might be further reviewed to complete a data entry.
Contact: USDOT, National Highway Traffic Safety Administration, National Center for Statistics and Analysis
Print source: USDOT, National Highway Traffic Safety Administration, Traffic Safety Facts (Washington, DC: Annual Issues).
International visitors data
Data on international visitors to the United States are based on international arrivals by air to the United States (excluding those from Canada and Mexico). Information is derived from the U.S. Department of Homeland Security Customs and Border Protection's Visitor Arrivals Program (I-94) and the U.S. Department of Commerce, Tourism Industries Office's Survey of International Air Travelers. The survey obtains data on overseas travel patterns, characteristics, and spending patterns of international travelers to and from the United States. Between 69,000 and 95,000 travelers are surveyed each year. The survey results are weighted so that they represent the international travel populations of U.S. residents and nonresidents based on U.S. Customs and Border Protection's data.
Contact: U.S. Department of Commerce (USDOC), International Trade Administration, Tourism Industries Office
Print source: USDOC, International Trade Administration, Office of Travel and Tourism Industries, Overseas Visitors to Select U.S. States and Territories (Washington, DC: Annual Issues); and USDOC, International Trade Administration, Office of Travel and Tourism Industries, Overseas Visitors to Select U.S. Cities/Hawaiian Islands (Washington, DC: Annual Issues).
Passenger border-crossing data
U.S. Customs and Border Protection personnel collect passenger border-crossing entry data for all U.S. land, air, and maritime ports. These numbers reflect all entries, and it is not possible to divide these data into separate entries for same-day and overnight travel or by country of residence for the traveler. Additionally, for border-crossing figures, the total number of people is not the number of unique individuals, but rather indicates the number of border crossings. Multiple crossings by the same individual count as multiple border crossings.
Contact: USDOT, RITA, Bureau of Transportation Statistics
Railroad industry and shipments data
The Association of American Railroads (AAR) database aggregates data from several sources and covers the freight railroad industry and movement of freight, both nationally and statewide. The state-level data include commerce, employment, and financial contributions.
The primary source of data for Class I railroads is Schedule 702 of the R-1 Annual Report to the Surface Transportation Board (STB) by individual carriers (100 percent reporting) and the Carload Waybill Sample. The primary source of data for non-Class I railroads is AAR's Profiles of U.S. Railroads from statistics supplied annually by nearly all operating U.S. freight railroads. Some of the data are estimated based on more aggregated, national figures.
The STB defines Class I railroads as having operating revenues at or above a threshold indexed to a base of $250 million (1991) and adjusted annually in concert with changes in the Railroad Freight Rate Index published by the Bureau of Labor Statistics. In 2008, the STB Class I threshold was annual operating revenue of $401.4 million. Declassification from Class I status occurs when a railroad falls below the applicable threshold for three consecutive years. Although few in number, Class I railroads account for over 90 percent of the industry's revenue.
AAR determines the number of non-Class I railroads through an annual survey sent to each U.S. freight railroad.
Historical reliability may vary due to changes in the railroad industry, including bankruptcies, mergers, and declassification by STB. Small data errors may also have occurred because of independent rounding in this series by AAR.
Contact: AAR, Policy and Economics Department
Railroad safety data
Railroads are required to file a report for each accident or incident to the Federal Railroad Administration (FRA). These include: 1) train accidents, reported on Form F 6180.54, comprised of collisions, derailments, and other events involving the operation of on-track equipment and causing reportable damage above an established threshold ($8,500 for 2008); 2) highway-rail grade crossing incidents, reported on Form F 6180.57, involving an impact between railroad on-track equipment and highway users at crossings; and 3) other incidents, reported on Form F 6180.55a, involving all other reportable incidents or exposures that cause a fatality or injury to any person or an occupational illness to a railroad employee.
Railroads are required by FRA regulations to use the current FRA Guide for Preparing Accident/Incident Reports when preparing reports.
The Systems Support Division of FRA maintains the Railroad Accident/Incident Reporting System (RAIRS), consisting of four databases: rail equipment, injury/illness, grade-crossing accidents, and railroad summary (freight and passenger). These databases include information on all railroad accidents, grade-crossing accidents, railroad employee casualties, and any other injuries on railroad property, and provide the basis for accident analyses and assessment as well as annual reports. The databases are updated monthly from information submitted by the railroads.
Contact: USDOT, Federal Railroad Administration, Office of Safety
Print publication: USDOT, Federal Railroad Administration, Railroad Safety Statistics (Washington, DC: Annual Issues).
Recreational boating safety and registration data
The U.S. Coast Guard, of the U.S. Department of Homeland Security, collects data on recreational boating accidents from two sources: 1) Boating Accident Report (BAR) data forwarded to the Coast Guard by jurisdictions with an approved boat numbering and casualty reporting system, and 2) reports of Coast Guard investigations of fatal boating accidents that occurred on waters under federal jurisdiction. Recreational Boating Accident Investigation data are used if submitted to the Coast Guard and are relied on as much as possible to provide accident statistics. In the absence of investigations, information is collected from reports filed by boat operators.
Boat operators are required to file a BAR if an accident results in 1) loss of life, 2) personal injury that requires medical treatment beyond first aid, 3) damage to the vessel and other property exceeding $2,000, or complete loss of the vessel, or 4) disappearance of a person from the vessel under circumstances that indicate death or injury.
Boat operators are required to report their accidents to authorities in the state where the accident occurred. States with approved boat numbering systems furnish the Coast Guard with BAR data. The minimum reporting requirements are set by federal regulation, but states are allowed to have stricter requirements. The Coast Guard reports recreational boating safety data in their report Boating Statistics, which covers accidents meeting the federal minimum reporting requirements.
The data in Boating Statistics cover boating accidents reported on waters of joint federal and state jurisdiction and exclusive state jurisdiction.
The Coast Guard believes nearly all fatal accidents and most boating accidents that result in serious injury (i.e., hospital admission) are included in Boating Statistics. A smaller percentage of nonfatal accidents are reported because of reporting thresholds, ignorance of the law, and difficulties enforcing the law. Federal law does not require the reporting of accidents on private waters where states have no jurisdiction. Reports of accidents on such waters are included when received by the Coast Guard if they satisfy the other requirements of inclusion. Accidents excluded are those in which the boat was used as a platform for other activities (e.g., swimming), and those in which a person dies of natural causes aboard a boat. However, the data do include accidents involving people in the water who are struck by their boat or another boat.
Contact: U.S. Department of Homeland Security (USDHS), U.S. Coast Guard, Office of Boating Safety
Print source: USDHS, U.S. Coast Guard, Office of Boating Safety, Boating Statistics (Washington, DC: Annual Issues).
Transborder surface freight data
The TransBorder Surface Freight Data is extracted from the Census Bureau's Foreign Trade Statistics Program and made available by the Bureau of Transportation Statistics. Import and export data are extracted from administrative records required by the Departments of Commerce and Treasury. This dataset incorporates all shipments entering or exiting the United States by surface modes of transport (i.e., other than air or maritime vessel) to and from Canada or Mexico. Prior to January 1997, this dataset also included transhipments in its detailed tables (i.e., shipments entering or exiting the United States by way of U.S. Customs ports on the northern or southern borders, even when the actual origin or final destination of the goods was other than Canada or Mexico). Shipments that neither originate nor terminate in the United States (i.e., intransit shipments) are beyond the scope of this dataset because they are not considered U.S. international trade shipments.
Users should be aware that the trade data fields (e.g., value and commodity classification) are typically more rigorously reviewed than transportation data fields (i.e., mode of transportation and port of entry/exit). Also, although this dataset provides surface transportation information for individual Customs districts and ports on the northern and southern borders, filing procedures for trade documents do not always correspond to the port where goods physically crossed the border. This is because the filer of information may choose to file trade documents at one port, while shipments actually enter or exit at another port.
Import data are generally more accurate than export data primarily because Customs uses import documents for enforcement purposes, while it performs no similar function for exports.
Contact: USDOT, RITA, Bureau of Transportation Statistics
Transit operating, financial, and safety data
Transit data are from the National Transit Database (NTD) produced by the USDOT, Federal Transit Administration (FTA). Data are collected from transit agencies that receive Urbanized Area Formula Program funds. Transit operators that do not report to FTA are those that do not receive federal funding, typically private, small, and rural operators. FTA reviews and validates information submitted by individual transit agencies. Reliability may vary because some transit agencies cannot obtain accurate information or may interpret certain data definitions differently than intended.
In 2008, 692 agencies submitted data to the NTD. Of that total, 101 transit agencies received exemptions from detailed reporting because they operated 9 or fewer vehicles and 15 received a waiver from detailed reporting. Thus, 576 individual reporters were included in the NTD.
Data are collected on a range of variables including capital and operating funding, transit service supplied and consumed, and transit safety and security. Transit operators must report fatalities, injuries, accidents, incidents, and property damage in excess of $25,000.
Contact: USDOT, Federal Transit Administration
Print source: USDOT, Federal Transit Administration, Data Tables (Washington, DC: Annual Issues); and USDOT, Federal Transit Administration, National Transit Database Reporting Manual (Washington, DC: Annual Issues).
Transportation establishment, employees, and payroll data
Data on employees, establishments, and payroll are taken from County Business Patterns, a database of employment in the United States using the North American Industry Classification System (NAICS). Data are collected annually. Data are extracted from the Business Register, the Census Bureau's file of all known single and multi-establishment companies. The Annual Company Organization Survey and quinquennial Economic Censuses provide individual establishment data for multi-location firms. Data for single-location firms are obtained from various programs conducted by the Census Bureau, such as the Economic Censuses, the Annual Survey of Manufacturer, and Current Business Surveys. They are also obtained from administrative records of the Internal Revenue Service, the Social Security Administration, and the Bureau of Labor Statistics.
Contact: USDOC, U.S. Census Bureau, Economic Planning and Coordination Division
Waterborne shipments data
The U.S. Army Corps of Engineers' (Corps) Navigation Data Center (NDC) collects data on waterborne commodity and vessel movements, domestic commercial vessel characteristics, port and waterway facilities, and navigation dredging projects.
The NDC's databases contain information on physical characteristics, infrastructure, and commodities for principal facilities on the U.S. coast, Great Lakes, and inland ports. The data consist of listings of port area's waterfront facilities, including information on berthing, cranes, transit sheds, grain elevators, marine repair plants, fleeting areas, and docking and storage facilities.
All vessel operators of record report their domestic waterborne traffic movements to the Corps via ENG Forms 3925 and 3925b. Cargo movements are reported according to points of loading and unloading. Excluded cargo movements are: 1) cargo carried on general ferries, 2) coal and petroleum products loaded from shore facilities directly into vessels for fuel use, 3) military cargo moved in U.S. Department of Defense vessels, and 4) cargo weighing less than 100 tons moved on government equipment. The Corps calculates ton-miles by multiplying the cargo's tonnage by the distance between points of loading and unloading.
An annual survey of companies that operate inland waterway vessels is the principal source of data for inland nonself-propelled, self-propelled, flag passenger, and cargo vessels. More than 3,000 surveys are sent to these companies, and response rates are typically above 90 percent.
Contact: U.S. Army Corps of Engineers, Waterborne Commerce Statistics Center
Print source: U.S. Army Corps of Engineers, Waterborne Commerce of the United States (New Orleans, LA: Annual Issues).