2

The Trucking and Bus Industries

Truck and bus operations in the United States are as diverse as the U.S. economy. Considerable heterogeneity in the truck and bus industries stems from operational characteristics ranging from fleet size and employer type to work schedules and on-the-job activities. Given this diversity, it is difficult to make simple statements about the relationship of such factors as work hours and periods of rest to fatigue among commercial motor vehicle (CMV) drivers and about drivers’ long-term health. Nonetheless, to help the reader understand the population regulated by the Federal Motor Carrier Safety Administration (FMCSA), this chapter reviews characteristics of the U.S. trucking and bus industries and provides a brief description of the lifestyles of CMV drivers and the policies and practices that influence driver fatigue and health. The chapter also touches on the attitudes in both industries toward driver fatigue and health and wellness programs and the information available on demographic and anthropometric variables with regard to CMV drivers.

Transportation in the United States occurs by road, rail, air, and waterways (boats) and can be broadly categorized into passenger and freight transportation. Passenger traffic is handled primarily by private automobiles (80%), planes (12%), trains (1%), and buses (7%) (U.S. Department of Transportation, 2014, Table 2-1). Freight traffic provides U.S. households with access to manufactured goods, and business establishments rely on freight transportation to move their raw materials and finished products. Trucks carry 67 percent of U.S. freight by weight and a much higher percentage by value. Trucks are crucial not only in the transportation

industry but also in many other sectors, such as agriculture, construction, and warehousing.

THE TRUCKING INDUSTRY

The trucking industry comprises hundreds of thousands of carriers and millions of drivers moving goods locally or in long hauls between cities. The industry is diverse, and different segments have different operational characteristics. FMCSA regulates trucks that are operated in interstate commerce or the transport of hazardous materials in quantities requiring a placard. There currently exists no single method for classifying truck drivers, but the major domains of classification are highlighted below.

Size of Carrier

Important differences exist among drivers by virtue of the size of the carrier for which they drive. Drivers may be employed by a large fleet or a small fleet, or they may be a one-truck operation, that is, an independent owner-operator.¹Table 2-1 shows the distribution of carriers and trucks by fleet size, displaying clearly the majority-minority industry structure. The majority of trucks on the road are operated by large carriers even though they represent a minority of the number of carriers in the industry. A very few of the large carriers are quite large, owning thousands of trucks. Conversely, as the table shows, smaller firms—those with 20 or fewer trucks—make up an appreciable fraction of the industry: nearly 95 percent of the more than 500,000 active truck carriers.

Types of Trucks

As shown in Table 2-2, truck drivers operate a variety of types of trucks. As a result, driver licensing requirements differ depending on the type of truck, as well as the type of load (discussed below). Any driver of a truck with a 26,001 or more lb gross vehicle weight rating (GVWR) must have a valid commercial driver’s license (CDL). The requirements for a valid CDL are set nationally, while each state regulates CDL testing and issues the licenses. Endorsements to the CDL are required for certain categories of truck and load type. For example, drivers of multiple-trailer trucks or any truck carrying hazardous materials must have the appropri-

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¹ There is no standard definition for “large” or “small” fleet. In compliance reviews published by FMCSA, carrier fleet size is categorized as very small (1-6 power units), small (7-20 power units), medium (21-100 power units), and large (> 100 power units). Available: https://ai.fmcsa.dot.gov/SafetyProgram/spRptReview.aspx?rpt=RVFS [March 2016].

TABLE 2-1 Distribution of Carriers and Trucks as of November 2014

NOTE: The companies are all registered with the Federal Motor Carrier Safety Administration to operate trucks in interstate commerce or to transport hazmat, and they have “recent activity.”

SOURCE: Truck count based on Motor Carrier Management Information System Carrier File.

TABLE 2-2 Classes of Trucks Operated by Truck Drivers by Gross Vehicle Weight Rating

NOTES: GVWR = gross vehicle weight rating, the maximum operating weight of a vehicle, including the driver and the cargo, as specified by the manufacturer. CDL = commercial driver’s license, which permits one to operate a commercial motor vehicle of a specific size.

SOURCE: For greater detail, see Burks et al. (2010).

ate endorsement. To qualify for this endorsement, they must demonstrate additional knowledge and skills beyond those required for the basic CDL. Since each state issues CDLs, FMCSA, in concert with the states, maintains a national database of CDL licenses, so a driver should not be able to obtain multiple licenses, and a driver with a suspended or revoked license in one state is precluded from continuing to drive a truck with a license from a different state.

Following are the common truck types driven by truck drivers:

• two- and three-axle straight trucks, with van, dump, or tank cargo bodies, such as the two-axle, six-tire vans used for local package delivery;
• two- and three-axle straight trucks pulling a trailer, which include small vans or dump trucks with equipment trailers;
• bobtail tractors (tractors with no trailer);
• tractor-semitrailers; and
• tractor two- or three-trailer combinations, which include the so-called STAA² doubles (two 28-foot trailers), turnpike doubles (two 40+-foot trailers), and triple-trailer combinations.

Employer

Many truck drivers are employed by private carriers that are not for-hire trucking firms. Private carriers transport their own goods or use the trucks in furtherance of their business. This means the operations of the trucks (times, road types, loads, etc.) are constrained by the needs of the business. Some private carriers move such a large volume of freight that they can operate like a big truckload (TL) or less-than-truckload (LTL) for-hire carrier (see definitions of TL and LTL in the following subsection). These are manufacturers, distributors, or retailers that move their own goods among factories, distribution centers, and retail outlets. They can have regular schedules, routes, and driving times, which can be controlled to address driver needs for regular rest, returning home every night after work, and so on. The drivers’ jobs can be like any other regular shift jobs. Other private carriers use trucks incidental to their primary business, such as construction, landscape, or retail.

Unlike the private carriers described above, for-hire carriers primarily provide freight transportation services for their customers; their business is not to transport their own freight.

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² STAA refers to the Surface Transportation Assistance Act of 1982, which allows large trucks, referred to as STAA trucks, to operate on routes that are part of the National Network.

Type of Load

Within the for-hire carrier domain, the distinction between TL and LTL services can have important ramifications for driver schedules and rest. In the case of TL services, the load is typically being transported from a single shipper to a single destination. LTL services combine shipments from multiple shippers and transport them to multiple destinations.

LTL carriers usually aggregate multiple small shipments into a load, transport them between terminals (as described below), and then distribute the shipments locally. TL carriers generally do not have such a terminal structure and focus on transporting large shipments, often for relatively long distances. Drivers for TL carriers typically pick up a full load from a shipper and move it directly to the receiver of the goods. A large majority of TL carriers’ business is regular and predictable under contracts or less formal agreements. Some TL carriers provide dedicated service, regularly hauling loads for a particular customer. Drivers in these situations may have predictable and regular schedules.

Big TL firms move enough freight that they can control dispatch to allow relatively regular schedules for their drivers. Other types of TL services are more occasional and episodic. For example, a TL firm or independent owner-operator may work with a freight broker. Such brokers find loads and arrange for carriers or owner-operators to haul them. In these situations, drivers can have much less regular schedules and unpredictable routes. The driver picks up a load, delivers it, then checks in with the broker for the next load; overall this process can result in unpredictable and irregular schedules.³

In contrast, a defining feature of LTL service is that, as noted above, many small loads from a variety of shippers are consolidated into one load (at a terminal), transported to destination terminals, and then dispersed to their destinations. Some LTL drivers operate primarily terminal to terminal, on regular schedules and routes. They drive tractors pulling one, two, or three trailers. At the terminals, the consolidated load may be broken down into smaller loads and then loaded on medium-duty vans and delivered by other drivers to recipients. Thus some LTL drivers make long-haul trips in big tractor-trailer rigs, while others perform package delivery in smaller trucks, in neighborhoods and to businesses. Although the package delivery drivers operate within a local area, their routes may vary day by day. They also spend a good part of each day loading and unloading at multiple locations.

Finally, some truck drivers work for private carriers, for which, as

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³ On the other hand, owner-operators in this situation are their own bosses and can more easily take a break when needed, without having to get permission or be accountable to a dispatcher.

described above, the truck operation is incidental to the main line of business. Some big retailers operate their own trucking arms, which provide LTL-like service between suppliers and retail stores. At the other end of the spectrum are construction firms that use large trucks to transport building materials and farmers who haul agricultural products to market.

Relationship to Hours-of-Service Regulations and Driver Fatigue

The major domains of classification described above influence drivers’ work schedules, the types and lengths of routes they drive, and what constitutes their daily duty. Given the scope of this report, it is useful to describe the complexities of these influences from the perspective of hours-of-service (HOS) regulations and driver fatigue:

• Regular versus irregular schedules
  • — LTL service typically entails more regular schedules, both for long-haul and package delivery operations. Regular schedules make it easier for drivers to comply with HOS regulations and may give them more opportunities to get regular rest and sleep at home each night.
  • — Private carriers may have regular schedules for the most part, with variations for some industries and in the case of some seasons or circumstances. For example, farmers and custom harvesters operate in response to the needs dictated by crops, while utility workers may work extended hours to restore service following an outage.
  • — Large TL carriers generally can provide more regular schedules and hauls, although that may not always be the case. Smaller TL carriers are likely to have less regular schedules and hauls, and their drivers may be away from home for longer periods and have less control over their schedules.
  • — Hazmat drivers transport dangerous cargo for which a timely delivery schedule becomes primary, which may place the driver in conflict with HOS regulations.
• Regular versus irregular routes
  • — As described above, TL carriers may be more likely than LTL carriers to have irregular routes, which in turn create difficulties in adhering to HOS regulations. Driver fatigue may be an issue when schedules are irregular.⁴

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⁴Crum and colleagues (2002) investigated the influence of motor carrier scheduling practices on driver fatigue for 116 truck companies and 66 motor coach companies and found that regular schedules and routes appeared to diminish fatigue.

• • — LTL package delivery entails elements of irregular routes, but the delivery operations are typically on a regular schedule, which should be conformable to the limits set by HOS regulations.
  • — Private carriers generally have regular routes and can manage operations to maintain regular schedules. As noted above, there are exceptions depending on their operations (e.g., seasonal demands related to agriculture or utility work).
• Length of haul⁵
  • — LTL and TL carriers, irrespective of fleet size, are more likely to have long than shorter routes.
  • — Large private carriers, such as the big retail companies, are more likely to have long than shorter routes.
  • — Smaller private carriers are more likely to have local or regional routes than longer routes.
• Primary activity in the job
  • — In for-hire operations, driving is the job almost by definition, so for-hire truck drivers are more likely than drivers for private carriers to face difficulties related to the limits of the HOS regulations, and driving-related fatigue may be an issue for them.
  • — There is more variability in private operations.
    • In some private operations, the primary job of the driver is driving. For these drivers, HOS regulations and driving-related fatigue are salient but fairly readily controlled in a well-managed firm.
    • In other private operations, truck driving is incidental to the job. HOS, especially time behind the wheel and driving-related fatigue, are less of an issue for these drivers unless they are told to put in more hours driving to get a critical job done. Under such circumstances, HOS regulations become relevant.
• Loading/unloading
  • — Big LTL carriers are involved in terminal-to-terminal operations; drivers likely are not involved in loading/unloading of their cargo.
  • — Drivers working for TL carriers, particularly small ones, may load and unload their cargo.
  • — The same may be true for drivers for private firms, except those working for big retail distribution companies.

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⁵ The terms long haul, regional, and short haul are often used to indicate the typical distance traveled to deliver a load. Long haul often means greater than 700 miles, regional between 300 and 700 miles, and short haul less than 300 miles.

Given the heterogeneity of the operational structure of truck driving, it is no surprise that big carriers have a different cost structure from that of medium-sized carriers and independent owner-operators—each industry segment faces a different average cost and average benefit curve. The market is highly segmented, with multiple players and intense competition leading to thin profit margins. According to IBIS World, the top six carriers represented about 10 percent of total sales in 2012. There are a small number of large players and a large number of small players, and none of the players hold substantial market power. As different players operate differently, the impact of HOS regulations varies across the industry. The challenge FMCSA faces is devising HOS regulations that do not compromise either the economic feasibility of different-sized trucking operations or highway safety.

WORKING CONDITIONS AND PAY OF A TRUCK DRIVER

Individuals working as long-haul truck drivers for smaller firms are more likely than drivers for larger firms to be away from home for most of the year and to be alone while driving. Their job is physically demanding because they may be required to load and unload cargo, which increases the risk of injuries. Given the current HOS regulations, being on duty 14 hours per day is common (Hege et al., 2015). Drivers can face long waiting periods during pickup and drop-off operations at warehouses and ports. The combination of long working hours, physically demanding tasks, and the pressures of a just-in-time economy creates a work environment for truck drivers that is not favorable to their health and has safety implications. Box 2-1 presents information from three studies on the workday of truck drivers.

Along with such issues, compensation provided to truck drivers plays a role in their decision to drive long hours. Truck drivers are paid in one of three general ways: (1) by the hour, (2) by the mile, or (3) by the load (which can include a percentage of the revenue associated with the load). The per-mile rate varies among employers and may depend on the type of cargo and the driver’s experience. Some long-distance drivers, especially owner-operators, are paid a share of the revenue from shipping. Along with these three types of compensation schemes, there exist hybrids that entail some combination of base pay and incentives. According to the Bureau of Labor Statistics, the median annual wage for heavy and tractor-trailer truck drivers was $38,200 in May 2012, with a wide range: the low-

est 10 percent earned less than $25,110, while the top 10 percent earned more than $58,910 (U.S. Bureau of Labor Statistics, 2014).

Two general dimensions of driver compensation are relevant to this study:⁶

1. Level of compensation—offering higher pay gives carriers the opportunity to attract and retain more highly skilled and safer drivers.

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⁶ Key among the laws that impact the compensation of truck drivers is the Fair Labor Standards Act exemption issued in 1938, which exempted the trucking industry from overtime compensation. For details, see http://www.dol.gov/whd/flsa/ [March 2016].

2. Type of compensation—paying by the mile, by the hour, or by the trip encourages drivers to drive more miles, hours, or trips, which contributes to driver fatigue. Regardless of the compensation method, it is common practice not to pay for loading and unloading. The laborious nature of these activities contributes to driver fatigue, which may be exacerbated by the fact that drivers may try to rush through them given that the time is unpaid.

It is not clear how the compensation scheme and hours of service interact and which predominates in terms of influencing safe driving. Paying by the hour incentivizes drivers to accumulate more time. On non-Interstate/freeway-quality roads, driving time often increases because of traffic volume, lower speed limits, and traffic lights. Thus distance may decrease, but driving time increases. This puts compensation and HOS regulations in conflict.

Belzer (2000) makes the point that deregulation in the trucking industry has led to negative externalities—declining wages and poor working conditions. Deregulation led to extreme competition in certain sectors of the industry, which in turn drove down wages as carriers were keen to find clients, and driver wages were a primary target for cutting costs (Belzer, 2000).

Evidence suggests that compensation and safety are linked. Using driver-level data from a large carrier—J.B. Hunt—Rodriguez and colleagues (2006) highlight the results of an experiment done by the carrier when it increased driver wages by 39.1 percent (on average) in a single move. Controlling for demographic factors, work experience, and operational factors, the higher wages reduced driver turnover and improved safety performance (lower crash probability on average). Another study (Thompson et al., 2015) found that manipulation of payment methods in a simulator produced poor decision making in fatigued drivers.

THE BUS INDUSTRY

Table 2-3 lists total bus registrations in 2013 by type of ownership. Like the trucking industry, the bus industry has various segments. Based on the type of operation run, the bus industry can be divided into four sectors:

1. Scheduled service—Bus companies offering a posted service, such as that operated by Greyhound and Megabus, which runs specific routes regionally throughout the United States and Canada. Drivers bid on these routes, and successful drivers receive a 90-day contract.
2. Tour and charter—Bus companies specializing in group tours and

TABLE 2-3 Bus Registrations in 2013, by Type of Ownership

SOURCE: U.S. Federal Highway Administration (2013, Table MV-10).

3. excursions. For this service, there is usually no repetitive fixed or specific route. Drivers are assigned this work a few days in advance.

4. Hybrid service—Bus companies operating both scheduled and tour and charter services.
5. Transit service—Buses operated by or for municipalities or regional authorities. They have a structured schedule by route.

Bus types and bus operators are at least as diverse as is the case for trucks, possibly more so. The above four are the dominant for-hire passenger operations, but there are others, including the following:

• school buses;
• shuttle buses belonging to any industry sector required to transport people as part of its service (e.g., airports, hotels, retirement homes, canoe liveries);⁷
• buses operated by private companies that transport employees between work sites or work locations;
• buses operated by municipalities and units of government that transport clients, prisoners, and workers; and
• buses operated by churches and other social service organizations.

Types of Buses

Types of buses driven in the United States include the following:

• School buses are specifically designed to transport school students.
• Motorcoaches are operated by bus companies running scheduled

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⁷ If a shuttle bus is big enough (seating for nine or more occupants, including the driver), it falls under HOS regulations.

• and tour and charter services and are used to convey passengers between cities.

• Transit buses are used to provide local transportation services.
• Van-based buses, such as shuttle buses, are used by companies or organizations for transporting people.

Employer

Most transit bus drivers work for local governments or urban transit systems, which are private companies that contract with a city or town to provide bus service. Most charter bus drivers work in the charter bus industry. Intercity bus drivers typically work in the interurban and rural bus transportation industry. School bus drivers and special-client bus drivers are usually employed by a school district or private transportation company that contracts with a district to provide bus service. Some school bus services are provided by the local government.

Size of Fleet

As in the trucking industry, the firm size of bus carriers varies, from large intercity carriers that operate a fleet of buses to small charter/tour carriers operated as a family business. Although not large in number, some large school bus operators provide service under contract with school districts, while some school districts operate their own buses.

WORKING CONDITIONS AND PAY OF A BUS DRIVER

According to the Bureau of Labor Statistics, about one-half of all bus drivers worked full-time in 2012. The rest either worked part-time or had variable schedules. Most school bus drivers work only when school is in session. Some make multiple runs if the schools in their district open and close at different times. Others make only two runs, one in the morning and one in the afternoon, so their work hours are limited. Transit drivers may work weekends, late nights, and early mornings. Charter or tour bus drivers travel with their vacationing passengers. Driver hours are dictated by a tour schedule, and drivers may work all hours of the day, as well as weekends and holidays. Some intercity bus drivers have long-distance routes, so they spend some nights away. Other intercity bus drivers make a round trip and return home at the end of each shift.

The median annual wage for transit and intercity bus drivers, which includes charter bus drivers, was $36,600 in May 2012. The lowest-paid 10 percent earned less than $21,320, and the highest-paid 10 percent earned more than $59,480. The corresponding median annual wage of

school or special client bus drivers was $28,080, with the lowest-paid 10 percent earning less than $17,610 and the highest-paid 10 percent earning more than $43,560.

ATTITUDES IN THE TRUCKING AND BUS INDUSTRIES TOWARD FATIGUE AND HEALTH AND WELLNESS PROGRAMS

The trucking and bus industries are playing a significant role in moving freight and people across the country, but safety remains an issue. In 2013, there were 3,541 fatal crashes involving large trucks in which 3,964 people were killed. The analogous statistics for fatal crashes involving a bus in 2013 are 280 and 310, respectively (U.S. Department of Transportation, 2013). Beyond loss of life, fatal crashes result in economic losses to the truck and bus companies and to society more generally.

Driver fatigue is one of many factors that contribute to crashes. How serious is the problem of fatigue in the bus and trucking industry? Estimates from police accident report-based databases, such as the General Estimates System and the Fatality Analysis Reporting System (FARS), suggest that fatigue plays a role in 1 to 2 percent of fatal crashes involving trucks and buses annually. However, these estimates are generally known to be underestimates because driver fatigue is difficult to detect. In 1990, the National Transportation Safety Board conducted in-depth investigations of 182 fatal-to-driver large-truck crashes and found fatigue to be a principal cause in 31 percent of these cases (56 of 182 crashes) (National Transportation Safety Board, 1990). Among all the factors investigated, fatigue turned out to be the most common cause. This 31-percent statistic should not be generalized to larger crash populations, such as “all fatal truck crashes” or “all truck crashes.” Nonetheless, it shows the importance of fatigue-related crashes for commercial drivers.

Putcha and colleagues (2002) analyzed FARS data looking for fatal crashes in which bus drivers were involved during the period 1995-1999. The five cases they found that were attributed to bus driver fatigue occurred in 1997, 1998, and 1999. In percentage terms, 0.3 percent of the bus drivers involved in fatal crashes during the 5-year period were coded as drowsy, fatigued, or asleep, which can be considered an underestimate for the reason mentioned above. One of the first studies of fatigue among bus drivers was conducted by Mackie and Miller (1978). Their most significant finding was that bus drivers who operate on irregular schedules suffer greater subjective fatigue and physiological stress relative to drivers operating on a regular schedule. A further description of studies investigating the linkage between driver fatigue and highway safety, including their limitations, is included in Chapter 7.

Efforts have been made over time to educate stakeholders in the

trucking and bus industries on the issue of driver fatigue and the importance of the health and wellness of CMV drivers. An outreach and communication program initiated in 1996, a collaborative effort of the Federal Highway Administration’s Office of Motor Carriers and Highway Safety and the American Trucking Associations, educated drivers and truck and bus companies about the risks of and the countermeasures for driver fatigue. The program arrived at a crucial finding: “if a driver’s lifestyle could be focused on health, wellness, and fitness, it would be a precursor to overall safety consciousness” (Krueger, 2010b, p. 3). Efforts by other agencies, such as the Centers for Disease Control and Prevention and the National Institute for Occupational Health and Safety (NIOSH), either through research studies or conferences, have likewise made the point that the occupational health of CMV drivers is a central issue in highway safety.

It can safely be said that there is industry-wide acceptance that fatigue is an issue. Big trucking fleets take proactive approaches to improve their safety figures by formulating various health and wellness programs based on internal research and evaluation. Regarding bus companies, Greyhound has a fatigue management initiative based on input received from focus groups made up of drivers, operations managers, and safety directors throughout the industry. Independent owner-operators are left to their own devices and the North American Fatigue Management Program serves as an information source for them. Chapter 8 describes the various initiatives of particular carriers, FMCSA, and industry associations with regard to fatigue management and health and wellness programs. Chapter 11 addresses how to evaluate the effectiveness of a web-based approach to education.

DEMOGRAPHIC AND HEALTH INFORMATION ON TRUCK AND BUS DRIVERS

As noted in Chapter 1, demographic and anthropometric information on truck and bus drivers is needed to examine the relationship between hours of service (or hours of sleep) and crash frequency. In examining this relationship, various confounders must be kept in mind. For example, the relationship could be considerably different for young and old drivers. Also, it is important to know various medical and psychological characteristics of the drivers, including whether they suffer from medical conditions (e.g., obstructive sleep apnea [OSA]); whether they take prescribed medicines, many of which can make one drowsy; and whether they have a propensity for risky driving.

Obtaining demographic information on the truck driver population is difficult as there have been no censuses of truck drivers, and the sur-

veys that have been conducted have by their design either excluded or underrepresented portions of the universe of truck drivers. Considerable information is available on drivers for most of the large carrier fleets. Also, the Owner-Operator Independent Drivers Association (OOIDA) has been conducting a biennial survey of its members since 1998. As is clear from its name, OOIDA focuses on owner-operators, so the information it collects excludes drivers that are employed by carriers. The drivers on whom these data are collected operate mainly tractor-semitrailers, which are almost all three-axle or larger trucks. The most salient feature of OOIDA members is that they are small carriers and probably operate a large number of TL loads.

According to OOIDA’s 2012 membership profile, 97 percent of owner-operators are male, their mean age is 55, and 48 percent live in rural areas with populations of less than 5,000. Their average height is 5’11”, their average weight is 221 pounds, and their average body mass index (BMI) is 31. Twenty-nine percent have no medical insurance. Their mean net income is $55,367. They drive an average of 110,000 miles per year. Forty-seven percent are away from home more than 200 nights per year. Twenty-nine percent believe their medical plan covers sleep apnea, and 6 percent are receiving treatment for that condition (OOIDA Foundation, 2015). As seen in Table 2-1, there were more than 500,000 active truck carriers as of October 2014. Carriers with 1 to 3 trucks make up about 75 percent of motor carriers but operate only 13 percent of all trucks, while those motor carriers with 50 or more trucks account for 50 percent of all trucks. Also, there are some very large carriers with thousands of trucks, and while they are small in number, they employ a large number of truckers. Therefore, the demographic information from the OOIDA membership profile provides information for a relatively small percentage of truck drivers.

With respect to anthropometric information on truck drivers, some information on the general health of truck drivers was collected in a survey sponsored in late 2010 by NIOSH and carried out by Westat. The sample design randomly selected 1,670 truck drivers at randomly selected truck stops along randomly selected limited-access highway segments. Truck drivers were defined as people for whom truck driving was their main occupation. In addition, this survey was restricted to those driving trucks with three or more axles. Furthermore, the drivers had to have driven a heavy truck 12 months or longer and had to have taken at least one mandatory 10-hour rest period away from home during each delivery run. Eligibility was established in a preliminary interview, and 1,265 drivers completed the full survey. The findings indicated that 69 percent were obese, with 17 percent of all respondents being morbidly obese. Fifty-one percent smoked, 14 percent were diabetic, and 38 percent were

not covered by health insurance. Twenty-seven percent admitted to sleeping on average less than 6 hours a night.

With regard to information on sleep received by truck and bus drivers, survey estimates are available from a poll of transportation workers conducted by the National Sleep Foundation in 2012 to understand their sleep habits and work performance. The poll was conducted among pilots, train operators, truck drivers, bus/limousine/taxi drivers, and a control group. Among the respondents were 203 truck drivers (mainly short-haul drivers employed by a company) and 116 bus drivers. Of these, 19 percent of truck drivers and 18 percent of bus/limousine/taxi drivers reported getting less sleep than needed.⁸ These figures were considerably below what was reported by pilots and train operators. As noted earlier, not getting adequate sleep at night causes daytime sleepiness, which results in taking naps during workdays. Fully 42 percent of truck drivers and 53 percent of bus/limousine/taxi drivers reported taking naps on workdays. The average number of naps per day (average amount of time napping) taken by truck drivers was 3.4 (43.5 minutes) and by bus/limousine/taxi drivers was 3.5 (42.1 minutes). The survey also included items on sleep disorders. Eleven percent of truck drivers and 10 percent of bus/limousine/taxi drivers reported ever being diagnosed with a sleep disorder, with the majority (more than 80%) reporting that disorder to be OSA.

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⁸ Respondents were asked to compare the hours of sleep they needed according to survey workers with the hours of sleep they were actually getting on workdays. On the basis of the responses, the proportions of those getting (1) more sleep than needed, (2) sufficient sleep, and (3) less sleep than needed on workdays were calculated.