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102. Transport Industry and Warehousing

Chapter Editor: LaMont Byrd

Table of Contents

Tables and Figures

General Profile
LaMont Byrd  

     Case Study: Challenges to Workers’ Health and Safety in the Transportation and Warehousing Industry
     Leon J. Warshaw

Air Transport

Airport and Flight Control Operations
Christine Proctor, Edward A. Olmsted and E. Evrard

     Case Studies of Air Traffic Controllers in the United States and Italy
     Paul A. Landsbergis

Aircraft Maintenance Operations
Buck Cameron

Aircraft Flight Operations
Nancy Garcia and H. Gartmann

Aerospace Medicine: Effects of Gravity, Acceleration and Microgravity in the Aerospace Environment
Relford Patterson and Russell B. Rayman

David L. Huntzinger

Road Transport

Truck and Bus Driving
Bruce A. Millies

Ergonomics of Bus Driving
Alfons Grösbrink and Andreas Mahr

Motor Vehicle Fuelling and Servicing Operations
Richard S. Kraus

     Case Study: Violence in Gasoline Stations
     Leon J. Warshaw

Rail Transport

Rail Operations
Neil McManus

     Case Study: Subways
     George J. McDonald

Water Transport

Water Transportation and the Maritime Industries
Timothy J. Ungs and Michael Adess


Storage and Transportation of Crude Oil, Natural Gas, Liquid Petroleum Products and Other Chemicals
Richard S. Kraus

John Lund

     Case Study: US NIOSH Studies of Injuries among Grocery Order Selectors


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1. Bus driver seat measurements
2. Illumination levels for service stations
3. Hazardous conditions & administration
4. Hazardous conditions & maintenance
5. Hazardous conditions & right of way
6. Hazard control in the Railway industry
7. Merchant vessel types
8. Health hazards common across vessel types
9. Notable hazards for specific vessel types
10. Vessel hazard control & risk-reduction
11. Typical approximate combustion properties
12. Comparison of compressed & liquified gas
13. Hazards involving order selectors
14. Job safety analysis: Fork-lift operator
15. Job safety analysis: Order selector


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Monday, 04 April 2011 16:45


Warehousing has long been a global industry; warehouses are integrally linked to commerce and transportation of goods—by rail, sea, air and road. Warehouses may be classified by the type of products stored: food products stored in dry, chilled or frozen sections; clothing or textiles; construction equipment or materials; machinery or machine parts. In the United States in 1995, for exemple, 1,877,000 workers were employed in trucking and warehousing (BLS 1996); this statistic cannot presently be disaggregated into workers by warehouse type or category. Warehouses might sell directly to external (retail) or internal (wholesale) customers, and the quantities retrieved for customers may be either full-pallet or less-than-full-pallet (one or more cases selected from a single pallet). Mechanical means (fork-lifts, conveyors or automatic storage and retrieval systems (AS/RS)) may be used to transport full-pallet or less-than-full-pallet loads; or workers, working without pallet movers and conveyors, may manually handle stored materials. Regardless of the nature of the business, the products stored or the mode of transportation servicing the warehouse, the basic layout is quite uniform, although the operational scale, terminology and technology will likely differ. (For additional information on AS/RS in warehousing, see Martin 1987.)

Products are delivered by shippers or suppliers to a receiving dock, where they are then entered into either a manual or computerized inventory system, assigned a storage rack or “slot” location (an address) and then transported to that location, usually by mechanical means (conveyors, AS/RS, fork-lift trucks or tractors). Once a customer order is received, the desired containers or cases must be retrieved from their slot location. Where full pallets are retrieved, mechanical means (a fork-lift or tractor operator) are used (see figure 1). When less than a full pallet load (one or more cases from a rack or slot) is to be retrieved, manual material handling is required, using a worker called a selector, who will choose the desired number of cases and place them either onto a mechanical pallet mover, a push cart or a conveyor. The individual customer order is assembled onto a pallet or similar container for shipment to the customer; a label, tag or other mark containing invoice/billing and/or routing instructions is then applied. This task may be performed by the order selector or fork-lift operator, or, where conveyors are used to deliver single cases for final assembly, by an assembler. When the order is ready for shipment, it is loaded by mechanical means onto the truck, trailer, railroad car or ship. (See figure 2).

Figure 1. A fork-lift truck in a warehouse in the United Kingdom being loaded with apples.


Figure 2. A dockworker in the United Kingdom using lifting machines to move quarters of beef.


Approximately 60% of the work activity in the warehouse is directly related to travel; the remainder relates to manual material handling. Aside from the important work of clerks, dispatchers, cleaners, supervisors and managers, the main work of the warehouse relating to the transporting and handling of goods is performed primarily by two classes of workers: fork-lift operators and selectors.

Intense worldwide competition and the rapid entrance of new firms have created the drive for increased labour and space efficiency, spawning a new discipline called warehouse management systems (WMSs) (Register 1994). These systems are becoming increasingly less expensive and more powerful; they rely on computer networks, bar coding, computer software and radio-frequency communications systems to vastly increase management and control of warehouse inventory and operations, allowing warehouses to improve customer order response times and responsiveness while dramatically increasing inventory accuracy and reducing costs (Firth 1995).

WMSs essentially computerize inventory and order dispatch systems. When incoming product from a supplier or shipper arrives at the receiving dock, bar code scanners record the product code and name, instantly updating the inventory database while assigning the incoming product an address in the warehouse. A fork-lift operator is then alerted to pick up and deliver the stock via a radio-frequency communications system mounted on the vehicle.

Orders from customers are received by another computer program which looks up the product address and availability of each item ordered in the inventory database and then sorts the customer order by the most efficient travel path to minimize travel. Labels with the product name, code and location are printed out for use by the order selectors who must then fill this order. While these features clearly help improve customer service and improve efficiency, they are important preconditions for engineered work standards (EWSs), which may pose additional health and safety hazards for both fork-lift operators and order selectors.

Information about each order—the number of cases, travel distances and so on—which is generated by the order dispatch programme can be further combined with standard or allowed times for each activity to calculate an overall standard time for selecting a particular customer order; it would be extremely time-consuming and difficult to retrieve this information without the use of the computer hardware and databases. Computer monitoring can then be used to record the elapsed time on each order, compare the actual with the allowed time and then compute an efficiency index, which any supervisor or manager can look up by pressing a few computer keys.

Warehouse EWSs have spread from the United States to Australia, Canada, the United Kingdom, Germany, Austria, Finland, Sweden, Italy, South Africa, the Netherlands and Belgium. While WMS systems themselves do not necessarily add safety and health hazards, there is considerable evidence to suggest that the resulting increased workload, lack of control over work pace and the impact of increased frequency of lifting contribute significantly to increased injury risk. In addition, the time pressure imposed by work standards may force workers to take risky short cuts and not utilize proper safe work methods. These risks and hazards are described below.


In the most basic warehouse, regardless of the level of technology and computerization, there are a myriad of basic health and safety hazards; modern WMSs can be linked with a different order of health and safety hazards.

Basic health hazards begin with potentially toxic materials which may be stored in warehouses; examples include petroleum products, solvents and dyestuffs. These require proper labelling, employee education and training and an effective hazard communication programme (including MSDSs) for all affected workers, who often know little about the health effects of what they are handling, much less proper handling, spill and clean-up procedures. (See, for example, the ILO Chemicals Convention, 1990 (No. 170), and Recommendation, 1990 (No. 177).) Noise may be present from gasoline or LP-powered fork-lifts, conveyors, ventilation systems and pneumatically-actuated equipment. Additionally, workers who operate such equipment may be subject to whole-body vibration. (See, for example, the ILO Working Environment (Air Pollution, Noise and Vibration) Convention, 1977 (No. 148), and Recommendation, 1977 (No. 156).)

Both fork-lift operators and selectors may be exposed to diesel and gasoline exhaust from trucks at the loading and receiving docks, as well as from fork-lifts. Lighting may not be adequate for fork-lift and other vehicle traffic or for ensuring proper identification of products desired by customers. Workers assigned to work in cold and frozen storage areas may experience cold stress from exposure to cold temperatures and air recirculation systems; temperatures in many freezer storage areas can approach –20ºC, even without wind chill factors being considered. Moreover, since few warehouses are air conditioned during warm months, warehouse workers, particularly those performing manual material handling, may be exposed to heat stress problems.

Safety hazards and risks are also many and varied. Besides the more obvious hazards evident when pedestrians and any motor-driven vehicle are put into the same work area, many of the injuries occurring among warehouse workers include slips, trips and falls from floors not kept free of ice, water or spilled product or that are poorly maintained; a number of injuries involve fork-lift operators who slip or fall while mounting or dismounting their fork-lift trucks.

Workers are often exposed to falling product from overhead racks. Workers may be caught in or between fork-lift masts, forks and cargo, resulting in serious physical injury. Wooden pallets handled by workers often result in exposure to slivers and related puncture wounds. Using knives to cut apart boxes and cases often results in cuts and lacerations. Workers who move boxes or containers on or off conveyors may be exposed to in-running nip points. Selectors, assemblers and other workers engaged in manual material handling are exposed to varying degrees of risk of developing low-back pain and other related injuries. Weight-lifting regulations and recommended methods for materials handling are discussed elsewhere in the Encyclopaedia.

Recordable injuries and lost workday cases in the US warehouse industry, for example, are considerably higher than those for all industry.

Data regarding injuries (and particular back injuries) among grocery order selectors, the group at greatest risk from lifting-related injuries, are not available on a national or international scale. The US NIOSH, however, has studied lifting and other related injuries at two grocery warehouses in the United States (see US NIOSH) and found that “all order selectors have an elevated risk for musculoskeletal disorders, including low-back pain, because of the combination of adverse job factors, all contributing to fatigue, a high metabolic load and the workers’ inability to regulate their work rate because of the work requirements” (NIOSH 1995).

A comprehensive application of ergonomics to the warehouse should not be confined to lifting and to order selectors. A wide focus is required, involving detailed job analysis, careful measurement and assessment (part of the job analysis begins with the job safety analyses below). A more comprehensive look at the design of racks and shelves is required, as is establishment of a closer working relationship with suppliers to design or retrofit fork-lift controls to reduce ergonomic risk factors (extensive reaches, foot flexion and extension, winging, awkward neck and body positions) and to design containers that are less heavy and bulky, with handles or grips to reduce lifting risk.

Corrective Actions

Basic health hazards

Employers, workers and trade unions should cooperate to develop and implement an effective hazard communication programme which emphasizes the three following fundamentals:

  1. adequate labelling of all toxic substances
  2. availability of detailed MSDSs that provide more detailed information about health effects, fire, reactivity, PPE, first aid, spill clean-up and other emergency procedures
  3. regular and relevant worker training in proper handling of these substances.


Lack of an effective hazard communication programme is one of the most frequent standards violations cited in this industry by the US Occupational Safety and Health Administration (OSHA).

Noise and vibration from mechanical equipment, conveyors and other sources require frequent noise and vibration testing and worker training, as well as engineering controls where needed. These controls are most effective when applied at the source of the noise in the form of noise insulation, mufflers and other controls (since most fork-lift operators are seated on top of the engine, vibration and noise dampening at this point are generally most effective). Lighting should be checked frequently and maintained at levels sufficient to reduce vehicle-pedestrian accidents and ensure that product identification and other information can be easily read. Heat (or cold) stress prevention programmes should be implemented for workplaces in warm and humid climates and for selectors or fork-lift operators assigned to cold storage or freezer rooms, to ensure that workers receive adequate breaks, fluids, training and information and that other preventive measures are implemented. Finally, where diesel or petroleum-based fuels are used, exhaust systems should be periodically tested for emissions of carbon monoxide and nitrogen oxides to ensure that they are within safe levels. Proper maintenance of vehicles and restricting their use to adequately ventilated areas will also help reduce the risk of over-exposure to these emissions.

Safety hazards for fork-lift and vehicle operators

Vehicle-pedestrian accidents are a constant risk in any warehouse. Pedestrian lanes should be clearly marked and respected. All vehicle operators should receive training in the safe operation of the vehicle, including traffic rules and speed limits; refresher training should also be considered. Mirrors should be installed at busy intersections or at blind corners to enable vehicle operators to check for traffic or pedestrians before proceeding, and operators should sound their horn before proceeding; back-up beepers or signals may also be considered. Dockplates from loading and receiving docks to the truck, railroad car or barge need to be sufficient to support the load and adequately secured.

Table 2 gives a job safety analysis for fork-lift operators, with recommendations.

Table 2. Job safety analysis: Fork-lift operator.

Job elements or tasks

Hazards present

Recommended protective actions

Mounting/dismounting fork-lift

Slipping/tripping on floor (grease, water, cardboard) during mounting/dismounting; back or shoulder strain from repeated incorrect entry/exit and bumping head on protective structure

Proper maintenance and clean-up of floors, particularly in high-traffic areas; exercising caution when mounting/dismounting; using three-point method to get in and out of fork-lift cab, being careful not to bump your head on overhead protective structure: grasping the support beams for the overhead protective structure with both hands, placing the left foot into the foot-hold (if one is provided) and then pushing off with the right foot and levering oneself into the cab.

Driving with and without loads

Pedestrian traffic and other vehicles might cross path suddenly; inadequate lighting; noise and vibration hazards; turning and twisting neck into awkward postures; steering may require wrist deviation, winging and/or excessive force; brake and accelerator pedals often require awkward foot and leg posture together with static loading

Slowing down in high traffic areas; waiting and sounding horn at all crossings with other aisles; exercising caution around other pedestrians; observing speed limits; ensuring proper lighting is provided and maintained through periodic inspections of illumination; installing and maintaining material that dampens noise and vibration on all vehicles and equipment; regular noise testing; operators should twist their upper torso at their waist, not at their neck, particularly when looking behind mirrors installed on the fork-lift and throughout the work facility will also help reduce this risk factor; purchasing, retrofiting and maintaining power steering and steering wheels which can tilt and raise to fit operators and avoiding winging; providing frequent rest breaks for recovery from static loading fatigue; considering redesign of foot pedals to reduce angle of foot (extension) and by hinging accelerator pedals to the floor

Raising or lowering forks with or without loads

Leaning and twisting of neck in order to see load clearly; reaching for hand controls which may involve excess reach or winging

Twisting or leaning from the waist, not from the neck; selecting fork-lifts which provide adequate visibility about the mast and which have hand controls within easy reach (located at side of operator, not on control console by steering wheel), but which are not so close or high as to involve winging; possibly retrofiting fork-lifts, with manufacturer’s permission.

Filling gas tanks or changing batteries

Changing LPG or gasoline tanks or batteries may require excessive and awkward lifting

Using at least two employees to lift, or using a mechanical hoist; considering redesign of fork-lift to facilitate a more accessible location for fuel tank


Implementing ergonomic solutions will require closer coordination with fork-lift and vehicle manufacturers; relying solely upon operator training and traffic rules will not eliminate hazards by itself. In addition, safety and health regulatory agencies have prepared mandatory standards for the design and use of fork-lifts—for example, requiring overhead guards to offer protection against falling objects (see figure 3).

Figure 3. An overhead guard fitted to a fork-lift truck.


Safety hazards for order selectors

Table 3 is a job safety analysis listing most of the corrective actions necessary to reduce the safety and lifting hazards for order selectors. However, just as improved fork-lift design to reduce ergonomic risk factors requires closer coordination with vehicle manufacturers, reducing safety and lifting hazards for order selectors requires similar coordination with designers of racking systems, consultants who design and install warehouse control systems and engineered standards systems and the vendors who store their products in the warehouse. The latter can be enlisted to design products that are less bulky, weigh less and have better handles or grips. Rack manufacturers can be very helpful in designing and retrofitting rack systems which allow the selector to stand upright during selection.

Table 3. Job safety analysis: Order selector.

Job elements or tasks

Hazards present

Recommended protective actions

Mounting/dismounting pallet jack

Slipping/tripping on floor (grease, water, cardboard) during mounting/dismounting

Proper maintenance and clean-up of floors, particularly in high-traffic areas; exercising caution when mounting/dismounting

Travel up and down aisles

Pedestrian traffic and other vehicles might cross path suddenly; lighting; noise

Slowing down in high-traffic areas; waiting and sounding horn at all crossings with other aisles; exercising caution around other pedestrians; observing speed limits; ensuring that proper lighting is provided and maintained; installing and maintaining material that dampens noise and vibration on all vehicles and equipment; regular noise testing

Select case from rack, walk to pallet, place case on pallet

Lifting injuries, shoulder, back and neck strain; bumping head on racks; heat stress; cold stress in freezer or cold rooms

Working in conjunction with vendors to reduce container weight to lowest possible levels and to install handles or better grips on bulky or heavy products; storing heavy products at knuckle height or higher; not storing products to require significant lifting over the shoulder, or provide steps, stairs or platforms; providing “turntable” pallets which can be rotated when selecting products, to avoid stretching; modifying carts or pallet jacks to raise higher, to minimize bending and stooping when placing product on the cart or pallet jack; restricting the “cube” of the pallet so that over-the-shoulder lifting is minimized; providing regular heat and cold stress monitoring; providing adequate fluids, conditioning programmes, clothing and frequent rest breaks

Separate pallets to wrap, mark or drop off at loading docks

Slipping/tripping on floor (grease, water, cardboard) during mounting/dismounting

Proper maintenance and clean-up of floors, particularly in high traffic areas; exercising caution when mounting/dismounting


Consultants who design and install warehouse control systems and engineered standards need to be more aware of the health and safety risks concerning the effect of work intensification on manual material-handling injuries. NIOSH (1993a, 1995) has recommended that more objective forms of determining fatigue allowance, such as oxygen consumption or heart rate, be used. They have also recommended that the height of the pallet being constructed (the “cube”) be limited to no more than 150 cm, and that there be an “order break” after one pallet has been assembled by the order selector, thus increasing the frequency of recovery periods between orders. In addition to more frequent breaks, NIOSH has recommended restricting overtime for workers based on engineered standards, considering worker rotation and installing “light duty” programmes for order selectors who return from injury or leave.



Thursday, 31 March 2011 16:42

General Profile

The transport sector encompasses industries that are involved in the transportation of goods and passengers throughout the world. This sector is structurally complex and vitally important to economies locally, nationally and globally.

Economic Importance

The transport sector is vitally important to the economic viability of nations. Transportation plays a key role in economically important factors such as employment, utilization of raw and manufactured goods, investment of private and public capital and generation of tax revenues.

In most industrialized countries, transport accounts for 2 to 12% of the paid employment (ILO 1992). In the United States alone, the Department of Transportation reported that in 1993, there were approximately 7.8 million employees in trucking-related firms (DOT 1995). The transport sector’s share in the gross domestic product (GDP) and total employment tends to decrease as the country’s income increases.

The transport sector is also a major consumer of raw materials and finished goods in most industrialized countries. For example, in the United States, the transport sector utilizes approximately 71% of all rubber produced, 66% of all petroleum refined, 24% of all zinc, 23% of all cement, 23% of all steel, 11% of all copper and 16% of all aluminium (Sampson, Farris and Shrock 1990).

Capital investment utilizing public and private funds to purchase trucks, ships, airplanes, terminals and other equipment and facilities easily exceeds hundreds of billions of dollars in industrialized countries.

The transport sector also plays a major role in generating revenues in the form of taxes. In industrialized countries, transport of passengers and freight is often heavily taxed (Sampson, Farris and Shrock 1990; Gentry, Semeijn and Vellenga 1995). Typically these taxes take the form of fuel taxes on gasoline and diesel fuels, and excise taxes on freight bills and passenger tickets, and easily exceed hundreds of billions of dollars annually.

Evolution of the Sector

In the early stages of the transport sector, geography greatly influenced what was the dominant mode of transportation. As advances were made in construction technology, it became possible to overcome many of the geographical barriers that limited the development of the transport sector. As a result, the modes of transport that have dominated the sector evolved in accordance with the technology available.

Initially, water travel over the oceans was the primary mode of transport of freight and passengers. As large rivers were navigated and canals were built, the volume of inland transport over the waterways increased significantly. In the late nineteenth century, transport over railways began to emerge as the dominant mode of transport. Rail transport, because of its ability to overcome natural barriers such as mountains and valleys through the use of tunnels and bridges, offered flexibility that waterways could not provide. Furthermore, unlike transport over waterways, transport over the rails was virtually unaffected by winter conditions.

Many national governments recognized the strategic and economic advantages of rail transport. Consequently, rail companies were awarded governmental financial assistance to facilitate the expansion of rail networks.

In the early twentieth century, the development of the combustion engine combined with the increased use of motor vehicles enabled road transport to become an increasingly popular mode of transport. As the highway and throughway systems were developed, road transport enabled door-to-door deliveries of goods. This flexibility far surpassed that of railways and waterways. Eventually, as advances were made in road construction and improvements were made to the internal combustion engine, in many parts of the world road transport became faster than rail transport. Consequently, road transport has become the most used mode of transport of goods and passengers.

The transport sector continued to evolve with the advent of airplanes. The use of airplanes as a means to transport freight and passengers began during the Second World War. Initially, airplanes were primarily used to transport mail and soldiers. However, as aircraft construction was perfected and an increasing number of persons learned to operate airplanes, air transport grew in popularity. Today, air transport is a very fast, reliable mode of transport. However, in terms of total tonnage, air transport handles only a very small percentage of freight.

Structure of the Sector

Information on the structure of rail systems in industrialized countries is generally reliable and comparable (ILO 1992). Similar information on road systems is somewhat less reliable. Information on the structure of waterways is reliable, having not changed substantially in the past few decades. However, similar information regarding developing countries is scarce and unreliable.

European countries developed economic and political blocs that have had a significant impact on the transport sector. In Europe, road transport dominates the movement of freight and passengers. Trucking, with a heavy emphasis on less-than-trailer-load freight, is conducted by small national and regional carriers. This industry is heavily regulated and highly fractured. Since the early 1970s, the total volume of freight transported by road has increased by 240%. Conversely, rail transport has declined by approximately 8% (Violland 1996). However, several European countries are working diligently to increase the efficiency of rail transport and are promoting intermodal transport.

In the United States, the primary mode of transport is over the roadways. The Department of Transportation, Office of Motor Carriers, reported in 1993 that there were over 335,000 firms operating medium and heavy trucks (DOT 1995). This included large companies that transport their own products, smaller private firms, and for-hire truckload and less-than-truckload common and contract carriers. The majority of these fleets (58%) operate six or fewer trucks. These companies operate a total of 1.7 million combination units, 4.4 million single-unit medium and heavy trucks and 3.8 million trailers. The road system in the United States increased by roughly 2% from 1980 to 1989 (ILO 1992).

The rail systems in the United States have declined, due primarily to the loss of Class 1 status of some rail lines, and due to the abandonment of less profitable lines. Canada has increased its rail system by some 40%, due mainly to a change in the classification system. The road system in Canada has decreased by 9% (ILO 1992).

In the industrialized nations of the Pacific Rim, there is great variability of the rail and road systems, due mainly to the different levels of industrialization of the respective countries. For example, rail and road networks in the Republic of Korea are similar to those in Europe, whereas in Malaysia, the rail and road networks are significantly smaller, but experiencing tremendous growth rates (over 53% for roads since 1980) (ILO 1992).

In Japan, the transport sector is heavily dominated by road transport, which accounts for 90.5% of the total Japanese freight transport tonnage. Approximately 8.2% of the tonnage is transported by water and 1.2% by rail (Magnier 1996).

Developing countries in Asia, Africa and Latin America typically suffer from inadequate transport systems. There is significant work underway to improve the systems, but a lack of hard currency, skilled workers and equipment inhibits the growth. Transport systems have grown significantly in Venezuela, Mexico and Brazil.

The Middle East in general has experienced growth in the transport sector, with countries such as Kuwait and Iran leading the way. It should be noted that due to the large size of the countries, sparse populations and arid climatic conditions, unique problems are encountered that limit the development of transport systems in this region.

An overview of railroad and road systems for selected countries and world regions is shown in figure 1 and figure 2.

Figure 1. World road network distribution 1988-89, kilometers.


Figure 2. World railroad network distribution, 1988-89, in kilometers.


Workforce Characteristics

The transportation sector contributes significantly to employment in most countries in both the private and public sectors. However, as per capita income increases, the impact of the sector on total employment decreases. The overall number of workers in the transport industries has declined steadily since the 1980s. This loss of workforce in the sector is due to several factors, especially technological advances that have automated many of the jobs related to the construction, maintenance and operation of transport systems. In addition, many countries have passed legislation which deregulated many transport-related industries; this has ultimately resulted in the loss of jobs.

Workers who are currently employed in transport-related industries must be highly skilled and competent. Due to the rapid advances in technology experienced in the transport sector, these workers and prospective workers must receive continual training and retraining.



The transportation and warehousing industry is fraught with challenges to worker health and safety. Those involved in loading and unloading of cargo and in storing, stacking and retrieving materials are prone to musculoskeletal injuries, slips and falls due to uncertain, irregular or slippery work surfaces and being struck by falling objects. See figure 1. Those operating and maintaining vehicles and other machinery are not only vulnerable to such injuries but also to the toxic effects of fuels, lubricants and exhaust fumes. If ergonomic principles are not heeded in the design of seats, pedals and instrument panels, drivers of trains, planes and motor vehicles (those used in warehousing as well on roads) will not only be subject to musculoskeletal disorders and undue fatigue, but will also be prone to operating mishaps that can lead to accidents.

Figure 1. Lifting parcels above shoulder height is an ergonomic hazard.


Teamster Union

All workers—and the general public as well—may be exposed to toxic substances in the event of leaks, spills and fires. Since much of the work is done out-of-doors, transportation and warehousing workers are also subject to extremes of weather such as heat, cold, rain, snow and ice, which can not only make the work more arduous but also more dangerous. Aviation crews must adjust to changes in barometric pressure. Noise is a perennial problem for those operating or working near noisy vehicles and machinery.


Perhaps the most pervasive hazard in this industry is work stress. It has many sources:

Adjusting to work hours. Many workers in this industry are burdened by the necessity of adjusting to changing shifts, while flight crews who travel long east-west or west-east distances must adjust to changes in circadian body rhythms; both of these factors may cause drowsiness and fatigue. The danger of functional impairment due to fatigue has led to laws and regulations stipulating the number of hours or shifts that may be worked without a rest period. These are generally applicable to aviation flight crews, railroad train crews and, in most countries, drivers of road buses and trucks. Many of the last group are independent contractors or work for small enterprises and are frequently forced by economic pressures to flout these regulations. There are always emergencies dictated by problems with traffic, weather or accidents which require exceeding the work hours limits. Led by the airlines, large transportation companies are now using computers to track employees’ work schedules to verify their compliance with the regulations and to minimize the amount of down time for both workers and equipment.

Timetables. Most passenger and a good part of freight transport is guided by timetables stipulating departure and arrival times. The necessity of keeping to schedules which often allow too little leeway is often a very potent stressor for the drivers and their crews.

Dealing with the public. Meeting the sometimes unreasonable and often forcefully expressed demands of the public can be a significant source of stress for those dealing with passengers at terminals and ticket offices and en route. Drivers of road transport must contend with other vehicles, traffic regulations and diligent highway traffic officers.

Accidents. Accidents, whether due to equipment failure, human error or environmental conditions, place the transportation industry at or near the top of listings of occupational fatalities in most countries. Even when a particular worker’s injuries may not be serious, post-traumatic stress disorder (PTSD) can lead to profound and prolonged disability, and in some instances it can prompt changing to another job.

Isolation. Many employees in the transportation industry work alone with little or no human contact (e.g., truck drivers, workers in control rooms and in railroad switch and signal towers). If problems arise, there may be difficulty and delays in getting help. And, if they are not kept busy, boredom may lead to a drop in attentiveness that can presage accidents. Working alone, especially for those driving taxis, limousines and delivery trucks, is an important risk factor for felonious assaults and other forms of violence.

Being away from home. Transportation workers are frequently required to be away from home for periods of days or weeks (in the maritime industry, for months). In addition to the stress of living out of a suitcase, strange food and strange sleeping accommodations, there is the reciprocal stress of separation from family and friends.

Health problems

Most industrialized countries require transportation workers, especially drivers and operating crew members, to take periodic medical examinations to verify that their physical and mental capacities meet the requirements established by regulations. Visual and hearing acuity, colour vision, muscular strength and flexibility and freedom from causes of syncope are some of the factors tested for. Accommodations, however, make it possible for many individuals with chronic disorders or disabilities to work without danger to themselves or others. (In the United States, for example, employers are mandated by the federal Americans With Disabilities Act to provide such accommodations.)

Drugs and alcohol

Prescription and over-the-counter medications taken for a variety of disorders (e.g., hypertension, anxiety and other hyperkinetic conditions, allergies, diabetes, epilepsy, headaches and the common cold) may cause drowsiness and affect alertness, reaction time and coordination, especially when alcoholic beverages are also consumed. Abuse of alcohol and/or illegal drugs is found frequently enough among transportation workers to have led to voluntary or legislatively mandated drug testing programmes.


The health and safety of workers in the transportation and warehousing industry are critical considerations, not only for the workers themselves but also for the public being transported or involved as bystanders. Safeguarding health and safety, therefore, is the joint responsibility of the employers, the employees and their unions and governments on all levels.



The National Institute for Occupational Safety and Health (NIOSH) studied lifting and other related injuries at two grocery warehouses (referred to hereafter as “Warehouse A” and “Warehouse B”) (NIOSH 1993a; NIOSH 1995). Both warehouses have engineered standards against which order selector performance is measured; those who fall below their standard are subject to disciplinary action. The data in table 1 are expressed in percentages of order selectors only, reporting either all injuries or back injuries alone each year.

Table 1. Back and all reported workplace injuries and illnesses involving order selectors at two grocery warehouses studied by NIOSH, 1987-1992.


Warehouse A: all injuries (%)

Warehouse B: all injuries (%)

Warehouse A: back injuries only (%)

Warehouse B: back injuries only (%)































Sources: NIOSH 1993a, 1995.

At the risk of generalizing these data beyond their context, by any reckoning, the magnitude of recordable injury and illness percentages in these warehouses are quite significant and considerably higher than the aggregate data for the industry as a whole for all job classifications. While the total injuries at Warehouse A show a slight decline, they actually increase at Warehouse B. But the back injuries, with the exception of 1992 at Warehouse B, are both quite stable and significant. In general terms, these data suggest that order selectors have virtually a 3 in 10 chance of experiencing a back injury involving medical treatment and/or lost time in any given year.

The US National Association of Grocery Warehouses of America (NAGWA), an industry group, reported that back strains and sprains accounted for 30% of all injuries involving grocery warehouses and that one-third of all warehouse workers (not just order selectors) will experience one recordable injury per year; these data are consistent with the NIOSH studies. Moreover, they estimated the cost of paying for these injuries (workers’ compensation primarily) at $0.61 per hour for the 1990-1992 period (almost US$1,270 per year per worker). They also determined that manual lifting was the primary cause of back injuries in 54% of all cases studied.

In addition to a review of injury and illness statistics, NIOSH utilized a questionnaire instrument which was administered to all grocery order selectors. At Warehouse A, of the 38 full-time selectors, 50% reported at least one injury in the last 12 months, and 18% of full-time selectors reported at least one back injury in the previous 12 months. For Warehouse B, 63% of the 19 full-time selectors reported at least one recordable injury in the last 12 months, and 47% reported having at least one back injury in the same period. Seventy per cent of full-time workers at Warehouse A reported significant back pain in the previous year, as did 47% of the full-time selectors at Warehouse B. These self-reported data closely correspond with the injury and illness survey data.

In addition to reviewing injury data regarding back injuries, NIOSH applied its revised lifting equation to a sample of lifting tasks of order selectors and found that all the sampled lifting tasks exceeded the recommended weight limit by significant margins, which indicates the tasks studied were highly stressful from an ergonomic point of view. In addition, compressive forces were estimated on the L5/S1 vertebral disc; all exceeded the recommended biomechanical limits of 3.4 kN (kilonewtons), which has been identified as an upper limit for protecting most workers from the risk of low-back injury.

Finally, NIOSH, using both energy expenditure and oxygen consumption methodologies, estimated energy demand on grocery order selectors in both warehouses. Average energy demands of the order selector exceeded the established criterion of 5 kcal/minute (4 METS) for an 8-hour day, which is recognized as moderate to heavy work for a majority of healthy workers. At Warehouse A, the working metabolic rate ranged from 5.4 to 8.0 kcal/minute, and the working heart rate ranged from 104 to 131 beats per minute; at Warehouse B, it was 2.6 to 6.3 kcal/minute, and 138 to 146 beats per minute, respectively.

Order selectors’ energy demands from continuous lifting at a rate of 4.1 to 4.9 lifts per minute would probably result in fatigued muscles, especially when working shifts of 10 or more hours. This clearly illustrates the physiological cost of work in the two warehouses studied to date. In summing up its findings, NIOSH reached the following conclusion concerning the risks faced by grocery warehouse order selectors:

In summary, all order assemblers (order selectors) have an elevated risk for musculoskeletal disorders, including low back pain, because of the combination of adverse job factors all contributing to fatigue, a high metabolic load and the workers’ inability to regulate their work rate because of the work requirements. According to recognized criteria defining worker capability and accompanying risk of low back injury, the job of order assembler at this work site will place even a highly selected work force at substantial risk of developing low back injuries. Moreover, in general, we believe that the existing performance standards encourage and contribute to these excessive levels of exertion (NIOSH 1995).



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