Publication Number: FHWA-HRT-12-001

What's in the Numbers?

by Brian Lomax

Here's a snapshot of the history of FHWA's Highway Statistics and a sampling of the data that make the publication so highly respected and so fascinating.

FHWA's Highway Statistics publication compiles a variety of data on the Nation's roads, including vehicle miles traveled, driver demographics, and the performance of existing infrastructure like this suburban highway.

Monday morning. As alarm clocks go off all across the country, Americans gather themselves to begin their workdays. Showered, dressed, and having finished their first cups of coffee, millions of Americans begin their daily commutes. Although some use public transportation, walk, or bicycle, many more will hit the roads in cars or trucks or on motorcycles only to find themselves…stuck in traffic.

Devising solutions to address the Nation's traffic problems and improve the transportation system's performance depends on the availability of high-quality data for decisionmaking. One critical data source is the Federal Highway Administration's (FHWA) annual Highway Statistics, which provides a comprehensive snapshot of the U.S. population's use of the roadway system.

"The goal of the Highway Statistics publication is to provide the most accurate statistical data," says FHWA Motor Fuel Analyst Marsha Reynolds. These data cover highway infrastructure, motor fuels, driver licensing, vehicle registration, State and local finance, and commercial and personal travel. Some of these data are crucial in apportioning funds to the States for various Federal highway programs.

Produced by the FHWA Office of Highway Policy Information, Highway Statistics compiles data used extensively by Federal, State, and local governments, institutions of higher learning, industry, consultants, professional organizations, and the public for a host of purposes. Policymakers, researchers, and academics have used the data to assess the performance and quality of the Nation's highway system and to identify potential problems and solutions.

The history of the Highway Statistics publication, followed by a selection of its key statistics and figures, demonstrates the diversity of data that FHWA publishes in each issue of Highway Statistics.

The data collected and published in FHWA's annual Highway Statistics are used by all levels of government and the public to assess the performance of the highway system.

Early History of Highway Statistics

Highway Statistics dates back to 1945, when FHWA's predecessor, the Public Roads Administration, released the publication's first issue. According to the preface of the inaugural issue, Highway Statistics would compile "statistical and analytical tables of general interest on the subjects of motor fuel consumption, motor vehicle registration, State highway user taxes, financing of State highways, and highway mileage."

The preface to the following year's publication acknowledged that "the favorable public reception of Highway Statistics 1945 indicates that the issuance of the tables in assembled, permanent form makes the data much more convenient and serviceable to…users."

In 1965, the U.S. Congress mandated that FHWA report biennially on the conditions, performance, and future investments needed by the Nation's street and highway systems. At that time, statistical data were fragmented, archaic, and incomplete, necessitating the assembly of large staffs to meet the objectives and data reporting requirements that Congress had outlined. These staffs made use of regularly reported data as well as ad hoc reports specific to each biennial reporting cycle.

Out of this manpower-intensive effort, a more streamlined approach emerged in 1978—a continuous, sample-based monitoring program that requires annual data reporting instead of relying on special studies every 2 years. FHWA dubbed the new approach the Highway Performance Monitoring System (HPMS). The new system featured an integrated database that contained basic information on the entire public road system and was capable of estimating current and future needs for program development and legislative initiatives. The HPMS contained State-specific data that met the needs of the Highway Statistics publication, as well as those of Federal-aid apportionment formulas and other purposes in the transportation community.

The content of Highway Statistics has evolved with new demands on FHWA for information and new ways to meet those demands. The development of the HPMS was followed in 1979 by the issuance of A Guide to Reporting Highway Statistics. The guide consolidated 16 separate State reporting forms into one volume. It also included instructions for collecting highway-related data on fuel consumption, vehicle registration, driver licensing, and the sources of funding for State and local government highway programs. Further, the guide served as a consolidated reference and promoted a unified reporting concept with an understanding of interrelationships among different reporting areas.

Highway Statistics evolved to turn HPMS tables into useful forms for the public and to take advantages of new data sources such as surveys and technology-based data. The most important, long-term survey conducted by FHWA is the National Household Travel Survey, started in the 1960s as the Nationwide Personal Transportation Survey. This survey is designed to measure the reasons why people travel and the consequences of that travel. Data collection technology is improving the efficiency and accuracy of surveys and has revolutionized FHWA's approaches to measuring traffic and infrastructure.

Technological Evolution

Significant technological advances in the 1980s and 1990s led to development of more sophisticated data collection equipment. For example, the collection of traffic data shifted from a manual observation activity to the use of pneumatic rubber hoses placed on the roadway for vehicle detection. This approach was followed by the use of magnetic loops embedded in the pavement. Corresponding advances took place in retrieving data, as traffic managers now could query remote sites in real time from a central location, which negated the need to visit local sites to gather data.

Also, the use of new technology, such as video logging, global positioning systems, geographic information systems, and electronic devices to measure pavement roughness, has streamlined roadway inventorying.

Today, compiling and analyzing data to publish Highway Statistics is one of the most important tasks performed by the Office of Highway Policy Information. FHWA uses these data to assess highway system performance under its strategic planning and performance reporting process developed in accordance with requirements of the Government Performance and Results Act of 1993, a series of laws designed to improve government project management. The act requires agencies to engage in project management tasks such as setting goals, measuring results, and reporting their progress.

"Retaining a historical context as we approach present policy is crucial to effective policy formation," says independent transportation consultant Alan Pisarski. "For much of my work, Highway Statistics going back to 1945 provides the fundamental source of historical trends in American travel behavior. Highway Statistics demonstrates to all of us how valuable that historical context can be."

Adds FHWA Office of Highway Policy Information Director David Winter, "the longevity of Highway Statistics is remarkable. There aren't that many reports that have been produced every year since 1945!"

In 2008 and 2009, motorists traveled a total of 6 trillion miles on U.S. highways, including this section of I–78 near the Berks/Lebanon County border in Pennsylvania.

Sample of the Data: VMTs

Highways are the transportation backbone of the country, providing a conduit along which people and goods move from coast to coast and everywhere in between. According to Highway Statistics 2009 (the latest year for which data were available at press time), Americans logged nearly 3 trillion vehicle miles traveled (VMT) that year, and it was essentially the same in 2008. Of that amount, 717 billion VMT (24 percent) of those miles were traveled on interstates, and two-thirds of all VMT were on urban roads.

"The VM-1, VM-2, and VM-3 tables in Highway Statistics are some of our most widely used tables," says Winter. "They combine highway mileage, travel, motor fuel, and registered vehicle data in a way that tells a story."

Table VM-1 is a summary of estimated travel by vehicle type and system. FHWA derives the total travel values from the highway functional system data contained in table VM-2, while pulling the vehicle type breakdowns from HPMS summary data. Simply put, the VM-1 table presents a picture of what the Nation's vehicles are doing on the interstate system. Economists, environmentalists, the Federal Government, and other stakeholders can use the table to provide an accurate assessment of the driving habits of motorists traveling in trucks, cars, and motorcycles.

"VMT has increased continuously since 1980 but declined from 2008 to mid-2009, reflecting economic conditions, "says Brad Gudzinas, a transportation specialist in the FHWA Office of Highway Policy Information. "Since early 2010, VMT resumed increasing until March of this year [2011]."

But despite a decline from 2007 to 2008, light-duty truck VMT (which includes travel in passenger and small commercial vehicles) showed a rebound in 2009. Light-duty truck VMT increased 0.8 percent to 2.7 trillion in 2009. Truck VMT declined for both single-unit and combination trucks in 2009. Light trucks, used primarily for personal transportation, track with automobile VMT. VMT for single-unit trucks, which includes commercial vehicles and some recreational vehicles, declined 5 percent to 121 billion in 2009. VMT for combination trucks, which includes tractor trailers and other large commercial vehicles, declined 9 percent to 168 billion in 2009. VMT of single-unit and combination trucks, which are mostly commercial vehicles, are greatly affected by the business cycle; in the current situation, commercial truck VMT is down significantly.

Data on Personal Vehicle Types

As the U.S. population grows and more cars take to the road, FHWA relies on its National Household Travel Survey, some results of which are reported in Highway Statistics, to learn more about the personal traveling behaviors of the American public. The 2009 survey, which does not include information about freight movement and truck ownership, asked respondents about the make, model, and year of private vehicles in their households.

The average age of private vehicles has continued to increase. In 2009, the average vehicle age was 9.4 years. In 1990, the average age of vehicles was 7.7 years, and in 2001, 8.9 years. In 2009, only 6 percent of vehicles were 1 model year old or newer.

The 2009 National Household Travel Survey also asked respondents whether any household vehicles were hybrids or alternative fuel vehicles, which includes those powered by ethanol, biodiesel, natural gas, propane, and hydrogen. Respondents indicated that 5 percent of household vehicles were either hybrid or powered by an alternative fuel.

Demographics of Noncommercial Drivers

Obtaining a driver's license marks a rite of passage for adolescents, while many older Americans view retaining one as a sign of continuing independence. "Our senior citizen drivers value their independence and mobility," says Gudzinas. "Many continue to work or volunteer well beyond what is thought of as retirement age. They appreciate that having a vehicle available helps them stay active."

In 2009, 87 percent of the driving-age population (age 16 and over) had a license—a total of 210 million licensed drivers. In 1960, just a few years after all States required driver licensing, there were 487 drivers for every 1,000 residents. As of 2009, that number had increased to 683 drivers for every 1,000 residents.

Highway Statistics also reveals insights on changes in the gender balance of the driving public. In 1970, 112 million drivers held licenses, and there were 1.3 male drivers for every female driver. However, by 2009, the number of licensed female drivers exceeded the number of licensed male drivers by 1 percent.

The number of licensed drivers per 1,000 residents differs significantly from State to State, ranging from 580 licensed drivers per 1,000 State residents in New York to 864 licensed drivers per 1,000 residents in Indiana. Alabama, Connecticut, Delaware, Maine, New Hampshire, and Vermont have among the highest numbers of licensed drivers per capita. States in the more rural northern Midwest and western mountain areas, such as Montana, Nebraska, Oregon, Washington, and Wyoming, also have higher numbers of licensed drivers per capita.

Those Americans between the ages of 45 and 54 had the greatest numbers of licensed drivers in 2009. Mirroring the population in general, 80 percent of licensed drivers are between the ages of 20 and 64. Five percent of licensed drivers are under the age of 20, while 16 percent are age 65 or older.

Data on Fuel Consumption

With more people driving—and driving for more years of their lives—fuel availability and options are taking on a greater role in the national discourse. As the cost of oil per barrel rises, so does the price for a gallon of gas. Although the Federal and State governments and industry researchers are devoting resources to developing alternative fuels and technologies to power motor vehicles, at this point gasoline, diesel, natural gas, and other petroleum-related products remain the primary sources of fuel for motor vehicles. In fact, U.S. vehicles consumed a total of more than 172 billion gallons of fuel in 2009. Of this total, 137 billion gallons (80 percent) are gasoline, and the remaining 35 billion gallons (20 percent) are special fuels such as diesel.

From 2008 to 2009, vehicle consumption of gasoline increased 0.3 billion gallons (0.2 percent), while special fuels consumption decreased 3.3 billion gallons (9 percent). Overall, vehicle fuel consumption decreased 1.7 percent from 2008 to 2009. Since 1970, total highway fuel consumption has increased 86 percent from 92 million gallons, an annual growth rate of 1.6 percent. Special fuels consumption is five times greater than in 1970, an annual growth rate of 4.3 percent.

At the State level, the five with the highest total fuel consumption—California, Florida, New York, Pennsylvania, and Texas—consume 56 billion gallons of fuel, which is 33 percent of total vehicle fuel consumption nationwide. The five States consuming the most diesel fuel—California, Illinois, New York, Pennsylvania, and Texas—consume 11 billion gallons, which is 30 percent of all diesel vehicle fuel consumption nationwide. These States lead in fuel consumption due to their high populations, as they are all within the top seven in terms of State population, with California and Texas being among the largest States in the country as well.

After more than 65 years in publication, Highway Statistics continues to provide the transportation industry and the public with data to guide policy decisions for roads like this one outside Reidsville, NC.

Making Statistics Reliable And Accessible

High-quality data on the Nation's highways can reveal much about both the economy and where the country stands in terms of mobility, fuel use, infrastructure condition, safety, and other critical issues. Other publications produced by FHWA have some of the same content as Highway Statistics but with different approaches and purposes. Our Nation's Highways, for example, is a graphical presentation for audiences using the Highway Statistics data in a more dynamic way. The Travel Volume Trends is a monthly publication and is presented in table format in Highway Statistics at the end of each year. The National Bridge Inventory is a table included in Highway Statistics in recent years. Also, FHWA's safety data program uses data on miles driven and age of drivers from Highway Statistics for transportation policy decisionmaking.

Throughout its history, Highway Statistics has evolved with the times as FHWA has strived to increase the publication's information value, improve the quality of its presentation, and expand its accessibility to the public. As time and technology have changed the way FHWA's Office of Highway Policy Information conducts business, Highway Statistics has moved into the technological age. In an effort to cut costs while considering the economic impact, the manual itself, once a massive undertaking of tables, numbers, and words, has been downsized to a "selected" booklet, featuring 25 to 30 of the most viewed and requested tables. The remaining tables are available, free of charge, at FHWA's "Office of Highway Policy Information" Web site (www.fhwa.dot.gov/policyinformation/index.cfm). Other technological advances, such as the creation of the Microsoft^® spreadsheet software, Excel^®, have made data entry, calculations, and graphing more efficient and less time consuming. Now available online in multiple formats such as HTML and PDF, the data in Highway Statistics are easier than ever for users to access and analyze.

"Highway Statistics may be the ultimate example of the cooperative joint Federal-State transportation process," says Pisarski, "each element bringing its skills together to produce a better final product."

Brian Lomax is a journalist working in the FHWA Office of Policy. He graduated in 2010 from Salisbury University with a degree in communications, specializing in journalism and public relations.

For more information, visit www.fhwa.dot.gov/policyinformation/statistics.cfm or contact Brian Lomax at 202–493–0599 or brian.lomax@dot.gov.