Differences in Truck Driver Labor Supply Between Owner-Operators and Employees

This study seeks to examine the work hours of truck drivers and the factors influencing drivers’ supply of labor to the freight transportation market. Recently, truck driver hours have been the object of regulatory scrutiny and regulation by the U.S. Department of Transportation, ostensibly for safety reasons. The new Hours of Service regulations are being blamed by some in the trucking industry for decreasing the amount of labor supplied by drivers by drivers entering other fields of employment. While drivers operate under this regulatory environment, the current study examines the other determinants of labor hours for truck drivers. These determinants are particularly relevant in light of projections of a shortage in the supply of truck drivers within the United States in the near future, and the associated costs and rates of driver turnover within the trucking industry. The nature of driver employment, either as an employee of a firm, or as an owner-operator, is also examined within the context of modern industrial organization theories of transaction costs and agency. ___________________________________________________ *The author wishes to acknowledge the assistance of Kristen Monaco at California State University – Long Beach in obtaining the data used in this study and to Dr. Duane Leigh and members of a graduate seminar in labor economics at Washington State University. Introduction A truism of the current market economy is the fact that practically all goods consumed or produced in the United States moved at some point by truck, either from its place of production to a center of manufacturing, or from a center of manufacturing to a final point of consumption. Integral to this process are the truck drivers who physically move these goods from place to place. In light of recent surveys (American Transportation Research Institute, 2005) indicating the importance of driver retention and driver shortages, examinations of the motivating factors in the labor supply are timely. This study seeks to examine the work hours of truck drivers and the factors influencing drivers’ supply of labor to the transportation market. Recently, truck driver hours have been the object of regulatory scrutiny and regulation by the U.S. Department of Transportation, ostensibly for safety reasons. The new federal Hours of Service regulations are effectively decreasing the amount of labor supplied by drivers and exacerbating an already existing truck driver shortage (Guido, 2005). While drivers operate under this regulatory environment, the current study examines other possible determinants of labor hours for truck drivers. These determinants are particularly relevant in light of projections of truck driver shortages within the United States in the near future, and the associated costs and rates of driver turnover within the trucking industry. The nature of driver employment, either as an employee of a firm, or as an owneroperator, is also examined within the context of modern industrial organization theories of transaction costs and agency. Previous studies have documented declining wages for truck drivers over the last 25 to 30 years (Hirsch and MacPherson 1997) and those factors of deregulation and human capital contributing to this decline (Belman and Monaco 2001). The American Trucking Association iv in 1997, identified driver retention and driver shortages as significant issues facing the trucking industry since the period of deregulation circa 1980. This study also found that several factors are crucial in retaining drivers such as “higher pay, more regular and predictable hours, greater benefits, or better equipment and working conditions.” Given these recent trends of declining wages and truck-driver shortages, this paper seeks to address several questions. First, what is the real wage rate of truck drivers in comparison to the actual number of hours worked? Do various performance incentive schemes affect a driver’s willingness to work? Do compensation and benefit programs provide incentives to drivers to provide more labor? What demographic, or specific individual characteristics affect the labor supply decisions of truck drivers? To what extent do these conditions affect a driver’s employment relation decisions? In order to answer these questions a unique data set based upon an extensive driver survey conducted by the University of Michigan, is used to construct a model of driver wages and labor supply. One factor that may influence labor supply decisions from the truck drivers’ perspective is the nature of the employment type that the drivers operate under. As noted by Nickerson and Silverman (2003), modern industrial organization theories of transaction costs and agency posit that the owner-operator form of employment should dominate truck driving. Reasons for this are the nature of trucks as non-specific capital assets that are easily redeployed (Williamson, 1985; Klein, Crawford and Alchian, 1978). This general lack of asset specificity in trucking argues against vertical integration by trucking firms (Tirole, 1988). Also, agency theory posits that delivery performance is usually easily measured, but that vehicle condition and depreciation are less easily monitored by trucking firms and these costs should be internalized by the drivers (Milgrom and Roberts, 1992; Tirole, 1988; Williamson, et al, 1975; Alchian and Demsetz, 1972) through driver ownership of the trucks. Yet, in a 1991 study by the American Trucking Association, almost 70 percent of truck drivers were employees of firms that own the tractor rigs, assign the shipments to various drivers and manage the logistical functions associated with transporting goods from origin to destination. One explanation for this divergence between theory and reality is in the organizational market niche the trucking firm seeks to exploit (Scheraga, 2005). Using the University of Michigan Trucking Industry Program (UMTIP) survey data, a final question is asked. Given the labor supply variables noted above, the nonspecific nature of truck assets, and that the apparently “structureless” nature of the truck driver labor market (Williamson, et al, 1975), what is the probability that a driver will choose to be the employee of a trucking firm, or choose an owner-operator form of employment relation? Data and Models Standard models of labors supply (Borjas 1999) identify many of the variables associated with the hours-of-work decisions made by participants in the labor force. In addition to the hourly wage, demographic variables such as educational attainment, race, marital status and gender have all been shown to have an effect on labor supply. Other factors that may influence labor supply decisions are nonlabor income and other forms of labor-related income such as health insurance, pensions and deferred income from savings plans, and the award of bonuses or imposition of penalties. This study uses information drawn from a truck driver survey conducted by the University of Michigan Trucking Industry Program (UMTIP) in 1997. The survey is an extensive questionnaire of 573 individuals regarding many aspects of truck driver’s working conditions and work lives (Belman, et al 1998). From this survey, 481 observations have been extracted in order to examine the hours-of-work decisions made by truck drivers in relation to factors such as hourly wage, payment schemes, the provision of benefits such as health insurance, pensions or deferred compensation programs, and the presence of bonuses or penalties related to service. Monaco and Willmert (2003) have also examined wages and hours using UMTIP data in comparison to Current Population Survey data from the U.S. Census Bureau. The current study also uses the UMTIP data to examine the factors influencing the employment relation decisions made by truck drivers. The survey also has the benefit of detailed demographic and employment characteristic information regarding the drivers. Information obtained from the UMTIP survey includes data on the drivers experience as a truck driver, union status, the type of employer, and whether the driver classifies their job as “over-the-road,” i.e., long-haul trucking, or local pick-up and delivery. Demographic information includes race, gender, marital status, spousal employment, the number of children, total family income in 1996, and the educational attainment of the driver. Educational attainment is classified as less than high school, some high school, high school, vocational or technical school, some college, associate’s degree and bachelor’s or higher college