An upsurge in retirements, coupled with workplace trends such as telecommuting, is bound to affect travel on U.S. highways. Here’s what transportation planners will want to know.

In 2011, the first baby boomers--defined as those born between 1946 and 1964--reached age 65. Their move into retirement is causing a dramatic demographic shift, raising the question of how commuting will change in a post-baby boomer world.

The labor force now includes generation X (born between 1965 and 1980) and the millennials (born 1981–2000). Together, these groups now surpass baby boomers in numbers in the workforce and therefore dominate the commuting population. The future of commuting may be very different from what it has been.

Not only are the ages of workers changing, but so are the occupations that can be done remotely. In addition to the impacts of demographic changes and working from home, another trend is growing that might affect the traffic picture: the rapid transformations caused by technology’s influence. The presence of self-driving vehicles, for example, might well be felt on U.S. highways as early as 2030.

In addition to demographic, economic, and technological changes, another trend is likely to affect the transportation outlook. Domestic migration of working-age people continues to favor the South and West, leading to highly varying growth rates across the Nation.

Finally, the United States is recovering from a serious recession, raising uncertainties as to which changes are cyclical in character, and therefore likely to return to historical patterns as the economy recovers, and which are truly structural in nature, indicating more permanent change. For example, a substantial number of post-recession jobs appear to be part time and thus might not contribute to peak-period travel in the same way as full-time employment would.

These trends point to a complex and difficult time for forecasting. The answers needed by the transportation community to guide policy and planning might not be known until future data are available from the American Community Survey, which is released annually, and until completion of the 2015/2016 National Household Travel Survey.

The Labor Force

Currently, the United States has more than 145 million workers in the labor force, representing about 45 percent of the total population. Approximately 70 percent of the civilian population between ages 18 and 64 are employed.

Although the number of households without any workers is growing because of baby boomer retirements and deaths, 84 million households in the United States still have at least one worker. Nearly 50 percent have two or more workers. In total, about two-thirds of workers live in a household with other workers.

Because so many households include two or more workers, a family or household’s residential choice needs to account for multiple work locations, in addition to other factors such as housing cost, quality of schools, and safety and security. Thus commuting to work locations, combined with school trips for family members, result in additional travel complexities.

The Role of Commuting

What role does commuting play in overall travel? Statistically, commuting comprises a relatively small and declining share of total travel. Its influence remains significant, however, because the home and workplace are the linchpins that guide much of trip making. In other words, commuting is often the formative factor in the daily flows of human activity and frequently shapes the timing and locations of other travel. Even though commuting represents only 16 percent of person trips, it is a critical factor in urban travel.

Commuting trips are important because of the following factors:

• Work trips are slightly longer than the average length of all trips for any purpose.
• They are a major share of travel during the morning and evening peak periods, and therefore are major components of congestion, driving the peak demands on the U.S. transportation infrastructure and services.
• The regularity and stability of the work commute influence both residential choices and decisions about business locations.
• Commuting represents about 16 percent of person trips, but because work trips are longer and have lower vehicle occupancy, they constitute nearly 28 percent of household vehicle miles of travel (VMT).
• Nearly 40 percent of person miles of travel on transit are for commuting.

These factors make commuting fundamental to the performance of the U.S. transportation system.

Other Trends

Over the past four decades, the history of commuting has corresponded with the working years of the baby boomer generation. The United States is now in a crucial phase of that generation’s impact on society as the baby boomers leave center stage. Just as the great challenge of the past period was to find jobs for all those would-be workers of the baby boomer generation, especially working women, today the new challenge is finding the skilled workforce to replace them.

Based on current projections of the U.S. Census Bureau, forecasters expect the working-age population to increase by only 6.5 million between 2015 and 2025. Given a 65 percent rate of participation in the labor force, only 4.2 million of these potential workers would actually be added to the labor force.

Currently, about 15 percent of persons over 65 are still working, which is up from about 12 percent in 1990, putting that demographic at about 10 million workers over 65 in the near future.

In total, these trends suggest that the role of commuting and its impact on transportation may change in the future. A key role for transportation will continue to be improving access to jobs and to workers. But the pace of growth in commuters is likely to be far more modest than it has been in the past. Nevertheless, the criticality of linking workers and jobs, especially those that are highly specialized, will continue to be challenging.

Location, Location, Location

The workers and the jobs are not likely to be evenly distributed. One-third of U.S. counties are losing population. Another third, primarily in metropolitan areas on the coasts and in the South, account for the vast majority of the current growth. The populations of the remaining counties, mostly rural, are remaining about the same.

Population growth in the South and the West is predicted to continue. Between 2010 and 2013, the fastest growing metropolitan areas (in order by percentage of growth) were Austin, TX; Raleigh, NC; Houston, TX; Orlando, FL; San Antonio, TX; Denver, CO; Dallas-Ft. Worth, TX; Washington, DC; and Charlotte, NC.

Today’s employers are more able to locate based on access to labor and quality of life considerations. The labor market of the future will be heavily influenced by workers’ preferences regarding locations and schedules rather than employers’ preferences.

Central cities of metropolitan areas enjoyed growth in previous decades, gaining about 5 million in population in both the 1990s and 2000s. However, the growth rate of about 7 percent in each decade was not enough for central cities to retain their share of metropolitan or national population. In fact, they declined overall from 33 percent of the metropolitan population in 1990 to under 29 percent in 2010. Rural areas also recorded losses in the range of 3 to 5 percent during that period. The majority of national growth occurred predominantly in suburban areas and significant suburban activity centers.

“In Colorado, demographic trends are having a variety of effects on commuting,” says Erik Sabina, manager of the Colorado Department of Transportation’s Information Management Branch. “Many center cities are gaining population after decades of decline. The city and county of Denver have gained 60,000 residents since 2010, a 10 percent increase, significantly altering commuting and congestion patterns. In many mountain communities, large increases in housing costs have priced many ordinary workers out of town, often requiring them to make long--and sometimes hazardous--commutes from less expensive towns in locations less desirable to tourists. Planners across our State rely on current data on travel behavior to respond to these challenges.”

Modes of Travel

Between 2000 and 2010, the Nation added 8.7 million workers, for a total of almost 137 million workers, which rose to almost 140 million in 2013.

Commuting trends were relatively stable over the long period from 1980 to 2013. Still, significant pattern changes emerged:

• Driving alone grew substantially during the early part of the period, but after that reached relatively stable levels; in this period in which the number of workers rose by about 43 million, the driving alone mode gained 58 million.
• The percentage of workers carpooling declined sharply, down to one-half what it was in 1980.
• Transit commuting declined through the early period but regained some of its lost share in the recent decade.
• Walking continued its long-term decline to a share level of half what it was in 1980.
• The major growth story was working at home, which almost tripled in numbers and doubled in mode share. This statistic measures only those whose primary workplace is home.

Below the surface, there are five notable trend changes within the detailed elements of mode choice:

First, the differences between male and female workers in mode choice have been lessening, as women’s jobs become more like men’s in that they increasingly work full time and year round, and more are in management and professional occupations. Most noteworthy is that the share of women driving alone to work now exceeds men’s share for the first time. Substantial gaps still remain between men and women in the use of transit, but women have greater shares on buses and far lower shares on commuter rail and ferries. Women’s use of bicycling for commuting is only about 40 percent of men’s.

Second, significant changes in mode shares among varying racial and ethnic groups are also occurring. In the past decade, both African-Americans and Hispanics showed substantial gains in the driving alone mode. African-Americans increased their share from 67 percent in 2000 to 72 percent in 2010, and Hispanics increased from 61 percent to 68 percent during the same period.

Third, notable declines among these two demographics were registered in carpooling. The share of Hispanic workers who carpool declined from 23 percent to 16 percent in the 2000 to 2010 period, and African-American workers who carpool declined from 16 percent to 10 percent, just about to the level of the national average.

Fourth, among African-American workers, the share using transit has declined from 12 percent to about 11 percent between 2000 and 2010, and the share of Hispanic workers using transit also declined slightly from 9 percent to 8 percent.

Finally, biking to work has attracted a great deal of media attention but still represents less than 1 percent of commuters. Among localities with more than 100,000 workers, the counties with the largest increases in biking to work since 2000 have been (starting with the highest) Multnomah County, OR (Portland); Benton County, OR; the District of Columbia; Santa Barbara, CA; and San Francisco, CA.

The overall decline in carpooling, in light of higher gas prices, a challenging economy, and public investment in incentivizing carpooling, is discouraging. Filling vacant seats in private vehicles is a seemingly efficient way to provide mobility while minimizing negative externalities, as carpooling moves more people with little or no additional vehicle travel. The magnitude of the multidecade decline in carpooling suggests that workers prefer the flexibility and convenience of driving alone and are reluctant to expend or tolerate the effort required to carpool. This trend might have repercussions because future scenarios involving autonomous vehicles envision shared travel being critical to accomplishing efficiency objectives. Again, higher vehicle occupancy means fewer vehicles are needed to make the same number of person trips.

Some of these trends may be attributable to the recession in which job losses were significantly greater in those industries with high carpooling tendencies, such as construction and large factory concentrations. Nevertheless, the United States is moving in a direction where racial, ethnic, and gender disparities are less significant as factors in travel trends, replaced by more broad measures such as education, income, occupation/industry, and location.

Travel Times And Start Times

Throughout the new century, average travel times to work have been stable. From 2000 to 2010, 26 States and the District of Columbia saw reductions in average travel times, but 24 States realized increases.

In 2000, the average national travel time to work was 25.5 minutes, and in 2011, it was exactly the same, rising only 0.3 of a minute by 2013. Much of this can be attributed to the recession and the consequent slow growth in work travel and softer overall travel demand.

A factor in this trend has been the decline in long-distance travel wherein so-called extreme commutes (those taking more than 90 minutes) actually declined compared to 2000, and trips over 60 minutes showed little change. If 20 minutes is considered a threshold for acceptable commute lengths, less than 44 percent of workers today meet this threshold. In 2000 close to half of workers made it to work in less than 20 minutes. This trend excludes those who work at home.

As expected, modal commute times vary. Walking--the shortest commute in terms of time--came in at just below 12 minutes, biking at above 19 minutes, driving alone was 24 minutes, while transit use varied from the 40-minute range for bus, light rail, and subway to between 60 and 70 minutes for commuter rail and ferry.

This first decade of the new century exhibited no sharp changes in travel start times. A significant attribute of start times, however, is the disparities among men and women. The 6:30 a.m. and earlier start time is a very male-oriented travel pattern. At 7 a.m., the traffic stream is a roughly equal mix in gender. By 7:30 a.m., women predominate.

Commuting Flows

Although travel times and modal shares are often major topics in discussions of commuting, perhaps the dominant questions are the following: Where are the workers, where are the jobs, and what are the flows like between them?

Over recent decades, there has been a growing balance as jobs follow population to the suburbs. But now population growth is re-emerging in central cities, such that the ratio of jobs to workers is moving closer to 1.0 (that is, one job per worker) in both areas. For example, Fairfax County, VA, had a ratio of approximately 0.7 (70 jobs per 100 workers) in 1980, rising to 0.85 in 2000 and almost a perfect 1.0 in 2010 with 574,000 jobs and 582,000 workers.

Even so, the skills mix of jobs and workers is the more significant factor in terms of workers being employed closer to home. Perhaps surprisingly to some, the tendency to travel long distances to work increases with wealth, as households choose other benefits over short commutes; either housing and school preferences or a preferred location may govern. Moreover, with about two-thirds of workers living in a household with other workers and lower job tenure, the ability to locate near a job is far more challenging today.

The result of these factors is a rising national pattern of cross-county flows. The long-term trend is in the number of workers who leave their county of residence to work each day. This trend has grown astronomically over the years, more than quadrupling since 1960, resulting in a doubling of the share of workers exported each day.

The Keys to the Future

Greg Slater, director of planning and preliminary engineeringat the Maryland State Highway Administration, reiterates the importance of commuting information: “Commute travel is a huge factor in Maryland for its population of more than 5.8million residents. Looking at our peak hour travel and the workforce makeup, 12 percent of the [resident] workers in Maryland are employed by the Federal Government centered in the Washington, DC, region, and 19 percent of workers are employed by the public sector.”

Slater continues: “Analyzing data on this system at a very detailed level in real time and at a higher level with national trends using products like [the American Association of State Highway and Transportation Officials’ (AASHTO)] Commuting in America series is critical for educating our traveling citizens and for developing the best value solutions for making commuting in Maryland more reliable. As the commute demographics change and technology continues to develop, we planners not only need to understand the challenges of today, but also the needs of tomorrow as the local economy grows and the function of our system changes with multimodal needs.”

Instead of a few dominant factors that define the future of commuting, the hallmark of the coming decade might be that it will be influenced by myriad, sometimes conflicting, pressures. The forecast appears to be varying and countervailing trends.

In what is perhaps the most complex and difficult period for planning and forecasting travel demand since World War II, some factors to consider include the following:

• In the near term, the key will be to discern whether current commuting and other travel behavior patterns are cyclical and part of the recession’s aftermath, or structural and opening distinct new patterns. In fact, it is increasingly clear that economic conditions explain a great deal of the current changes in travel.
• One clear reality is that the boomer generation is reaching the end of its working years, and modest population growth will limit workforce expansion unless significant changes occur. In addition, the places where baby boomers live and grow older will influence where the demand will occur for the fast-growing jobs in personal and home health, physical and occupational therapy, and nursing.
• To meet the demand for more workers, several approaches will be needed, including enhancing access over long distances to workers with needed skills.
• Population and jobs will be centered even more in metropolitan areas and in the suburbs. Millennials most likely will prefer living in big cities and are most eager to live in places with extensive public transit options, according to the National Cooperative Highway Research Program (NCHRP) Report 750, Strategic Issues Facing Transportation.
• Millennials now commute by public transit more than any other generation, but the youngest workers have always been more likely to use transit than other age groups. Whether millennial workers will remain loyal transit users as they increase their income and possibly purchase vehicles is not yet clear.
• Diminishing differences among men, women, and racial and ethnic groups will force a new focus on other factors that influence commuting, such as income, education, occupation, industry, and geographic locations.
• The population will continue to shift to the South and West regions of the country.
• Lengths of work trips are likely to increase as more workers seek to connect with more specialized positions in ever-larger metropolitan areas.
• In a world of relatively footloose industries that can locate almost anywhere but face looming scarcities of skilled workers, employers may more readily relocate near where the workers are or want to be.
• Part of employer responses will be greater flexibility in working hours and schedules.
• Among the potential factors affecting commuting in the future, but still emerging at this time, are new technology-assisted “semimodes” of transportation and transportation service business models. These new models include transportation network companies such as Uber and Lyft, technology-assisted payment, dynamic or variable pricing, scheduling, ridematching, and vehicle-sharing capabilities. With 64 percent of U.S. adults owning a smartphone (up from 35 percent in 2011), the influence of personal technology on transportation is clear and likely will increase in importance.
• Other external factors such as environmental constraints, shifts in energy availability and costs, and changes in infrastructure capacity and condition also may have an impact on future commuting.

The Federal Highway Administration currently has a project underway that includes analyses of current and future trends in travel behavior. The Next Generation of Travel project is a compilation of work that focuses primarily on youth ages 18–29, youth travel decisions, lifestyle changes, technology, and geography. (See www.fhwa.dot.gov/policy/otps/transfutures.cfm for more information.)

Similarly, the NCHRP report, The Effects of Socio-Demographics on Future Travel Demand, includes discussion of the uncertainty of future forecasts because of fundamental societal changes that cannot yet be foreseen. (See http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_750-v6.pdf.)

In an era of rapid change, it is critical that transportation planning professionals and policymakers have access to current, high-quality information on travel demand and the performance of the transportation system. Developing a strong understanding of future commuting and other travel behavior, and having adequate data and analyses to support that understanding, are essential to helping ensure that the transportation system stands ready to support improved mobility for people and goods while mitigating the negative impacts of transportation to the greatest extent possible.

Alan Pisarski is a writer and consultant in transportation policy, travel behavior, and statistics. In addition to books that focus on commuting and travel behavior trends, he has provided continuity to the Commuting in America report series and played a significant role in the Transportation Research Board’s Transportation History Committee and with the National Household Travel Survey.

Steve Polzin, Ph.D., is director of mobility policy at the Center for Urban Transportation Research at the University of South Florida. Polzin’s work focuses on travel behavior and transportation policy, especially commuting, public transportation, and the impacts of demographic, economic, and technology changes on future travel. His B.S. degree in civil engineering is from the University of Wisconsin-Madison, and master’s and Ph.D. degrees are from Northwestern University.

Elaine Murakami recently retired from her position as a community planner with FHWA’s Office of Planning. Her work centered on regional and national surveys of travel behavior, including use of the American Community Survey for the Census Transportation Planning Products, and the use of new technology such as GPS and smartphones for regional surveys.

For more information, contact Brian Gardner at 202–366–4061 or brian.gardner@dot.gov.