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Laws and Regulations > Lookback Reviews > Regulatory Review of 29 CFR 1926, Subpart P: Excavations
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Regulatory Review of
29 CFR 1926, Subpart P:

Excavations

Pursuant to
Section 610 of the Regulatory Flexibility Act
and Section 5 of Executive Order 12866

Occupational Safety and Health Administration
Directorate of Evaluation and Analysis
Office of Evaluations and Audit Analysis

March 2007

Table of Contents

Executive Summary
1. Introduction and Background
   1.1 Nature of the Review
   1.2 Overview of Protective Systems Guarding Against Cave-Ins
   1.3 Regulatory History
   1.4 Requirements of the Excavations Standard
2. Industry Profile, Trends, and Issues
   2.1 Background
   2.2 Industry Sectors Affected by the Standard
   2.3 Economic Performance of Industry Sectors
   2.4 Developments in Technology
3. Fatalities
   3.1 National Fatalities and Trends
   3.2 Fatalities by Industry
   3.3 Fatalities by Cause of Death
4. Compliance with the Standard
   4.1 Compliance Violations
   4.2 Penalties
5. Cost Analysis
   5.1 Overview and Key Findings
   5.2 Cost Analysis of Protective Systems
   5.2.1 Sloping
   5.2.2 Trench Boxes
   5.2.3 Aluminum Shoring
   5.2.4 Timber Shoring
6. Public Comments
7. The Excavations Standard and Small Businesses
   7.1 Estimation of the Number of Small Businesses
   7.2 Distribution of Firms by Number of Employees
   7.3 Fatalities by Firm Size and Number of Workers on Site
   7.4 Impacts on Small Businesses
8. Section 610 Review
   Nature of Comments Received
9. Executive Order 12866 Review of the Standard
10. Summary and Conclusions
APPENDIX I: REGULATORY FLEXIBILITY ACT, SECTION 610
APPENDIX II: INTRODUCTION AND SECTION 5 OF EXECUTIVE ORDER 12866 REGULATORY PLANNING AND REVIEW
Appendix III: Crosswalk Between SIC Codes and NAICS Codes
Appendix IV: Outreach Materials


Executive Summary

On October 31, 1989, OSHA issued a final revised standard for excavation and trenching1. The revision updated the previous standard by simplifying many of the existing provisions, adding and clarifying definitions, eliminating duplicate provisions and ambiguous language, and giving employers added flexibility in providing protection for employees. In addition, the standard provided several new appendices. One appendix provided a consistent method of soil classification. Others provided sloping and benching requirements, pictorial examples of shoring and shielding devices, timber tables, hydraulic shoring tables, and selection charts that provide a graphic summary of the requirements contained in the standard.

This regulatory review of the Excavations Standard meets the requirements of both Section 610 of the Regulatory Flexibility Act and Section 5 of Executive Order (EO) 12866. Under Section 610, this review examines whether the standard should be continued without change, rescinded, or amended to minimize any significant impact on a substantial number of small entities considering the continued need for the rule, comments and complaints received, complexity of the rule, whether the rule is duplicative, and the degree to which technology and economic conditions have changed since its issuance. Under Section 5 of EO 12866, this review examines whether the standard has become unjustified or unnecessary as a result of changed circumstances, and whether the standard is compatible with other regulations or is duplicative or inappropriately burdensome in the aggregate. This review also ensures that the regulation is consistent with the priorities and the principles set forth in EO 12866 within applicable law, and examines whether the effectiveness of the standard can be improved. To assist OSHA in this review, OSHA requested public comments on these issues.

The Section 610 review of the standard finds the following:
  • There is a continued need for the standard. The annual number of trenching and excavation fatalities has declined from an estimated 90 fatalities per year prior to the enactment of the 1989 standard, to approximately 70 per year since 1990. This 22% reduction is even more impressive given the 20% real increase in construction activity over this period. Therefore, in relation to increased construction activity, fatalities have been reduced by more than 40%. Although the standard has improved safety, it remains needed in light of the ongoing occurrence of related fatalities most of which result from violations of the standard. OSHA intends to expand outreach and maintain enforcement to further reduce fatalities.
  • The standard was revised in 1989 to reduce complexity and add clarity. There is no indication that employers are unable to comply due to the complexity of the revised standard. Nonetheless, public comments suggested some ways in which the standard might be simplified or clarified (although some argued that any changes would only serve to confuse and discourage those who now understand and follow the standard). The expanded outreach will address these matters.
  • In general, the standard does not overlap, duplicate, or conflict with other state or federal rules. Several commenters, however, identified a possible conflict between the Excavations Standard and OSHA's standard for confined spaces. OSHA will address this issue in its future rulemaking for confined spaces in construction.
  • Economic and technological trends have not reduced the need for the standard. However, the development of so-called "trenchless" technologies (e.g., directional boring machines) has added a new dimension to excavation work (including additional hazards) that OSHA will monitor.
  • Public comments contained some specific suggestions for how the standard could be made more effective, although the comments were divided as to whether or not the standard should be modified. In light of the effectiveness of the standard, the certainty it has created, and limited regulatory resources, major modifications are not of high priority.
  • The National Transportation Safety Board (NTSB) recommended the OSHA amend the Excavations standard to require employers to notify appropriate authorities after excavation activities create a gas leak or leak of other hazardous substances. Since then, the "Pipeline Inspection, Protection, Enforcement, and Safety Act (PIPES) of 2006" has been enacted. Section 2 of PIPES requires all persons (including employers) engaged in demolition, excavation, tunneling, or construction to immediately call 911 if: (1) they damage a pipeline that may endanger life or cause serious bodily harm or damage to property; and (2) such damage results in the escape of flammable, toxic, or corrosive gas or liquid. The enactment of PIPES may obviate the need for OSHA to promulgate a standard implementing the NTSB's recommendation. It also may affect OSHA's authority to issue such a standard. OSHA will monitor the implementation of PIPES and consider whether amending the excavations standard as suggested by NTSB is necessary and appropriate.
  • The standard does not impose an unnecessary or disproportionate burden on small businesses or on industry in general. The cost of protective systems has decreased by about 10 percent in real dollars between 1990 and 2001. The number of small businesses engaged in excavation activity has increased and the percentage of excavation work done by small business has increased. Real construction activity has increased.
Based on the findings of this review, OSHA finds that the Excavations Standard should be continued. OSHA also believes that further increases in safety might be achieved, through increased outreach and training.

OSHA's review of the Excavations Standard under Executive Order 12866 finds the following:
  • The standard has significantly reduced the annual number of fatalities (from 90 to 70, on average) resulting from accidents involving excavations and trenching, despite growth in the relevant industry sectors. The standard remains justified and necessary in light of ongoing hazards and fatalities.
  • In general, the standard is compatible and not duplicative with other state or federal rules. Several commenters, however, identified a possible conflict between the Excavations Standard and OSHA's standard for confined spaces which OSHA will address in a further rulemaking for confined spaces in construction.
  • The standard remains consistent with the President's priorities to the extent that it has produced the intended benefits, a reduction in trenching and excavation fatalities and injuries, while not causing negative economic effects.
  • In light of suggestions contained in public comments, and given the ongoing incidence of accidents, injuries, and fatalities occurring each year during excavation and trenching activities, generally from violations of the standard, OSHA intends to evaluate whether further increases in safety can be achieved by various means such as expanded outreach and training.

1. Introduction and Background

Excavation accidents and fatalities most frequently involve cave-ins of excavations or trenches, but also may result from a variety of other accident types, including machine accidents, falling objects, electrocution, vehicular accidents, explosions or fires, falls, drowning, and asphyxiation due to noxious fumes. In 1987, prior to OSHA's 1989 revision of the standards protecting workers in or near excavations and trenches, OSHA estimated the average annual number of excavation-related fatalities at 902. OSHA also estimated that the 1989 revision to the standard would reduce annual fatalities to 70 (a 22 percent reduction).

It now has been over ten years since the promulgation of the 1989 revision to the Excavations Standard. The purpose of this study is to "look back" and review the current standard, in accordance with Section 610 of the Regulatory Flexibility Act and Section 5 of Executive Order 12866, to determine whether the rule has functioned as intended, whether it could be simplified or improved, or whether it is no longer needed and should be rescinded.

The study methodology consists of evaluating the industries that conduct excavation and trenching activities, examining available literature and data on accidents and compliance issues, assessing trends in compliance costs, and considering issues raised by the public with respect to the standard. The remainder of this first chapter provides background information that is helpful in understanding the issues and analyses presented in this study. Section 1.1 discusses, in additional detail, the nature of the review. Section 1.2 briefly introduces and summarizes the basic types of systems available to protect workers from cave-ins of soil at sites where excavation or trenching activities are being conducted. Section 1.3 provides an overview of the history of the Excavations Standard. Finally, Section 1.4 describes the provisions in the current standard.

1.1 Nature of the Review

In 2002, the Occupational Safety and Health Administration (OSHA) began a review of its Excavations Standard under Section 610 of the Regulatory Flexibility Act3 and Section 5 of Executive Order (EO) 12866 on Regulatory Planning and Review4.

The purpose of a review under Section 610 of the Regulatory Flexibility Act:
    "(S)hall be to determine whether such rule should be continued without change, or should be rescinded, or amended consistent with the stated objectives of applicable statutes to minimize any significant impact of the rules on a substantial number of small entities."

    "The Agency shall consider the following factors:

    1. The continued need for the rule;
      2. The nature of complaints or comments received concerning the rule from the public;
    2. The complexity of the rule;
    3. The extent to which the rule overlaps, duplicates or conflicts with other Federal rules, and, to the extent feasible, with State and local governmental rules; and
    4. The length of time since the rule has been evaluated or the degree to which technology, economic conditions, or other factors have changed in the area affected by the rule."
The review requirements of Section 5 of EO 12866 require agencies:
    "To reduce the regulatory burden on the American people, their families, their communities, their State, local, and tribal governments, and their industries; to determine whether regulations promulgated by the [Agency] have become unjustified or unnecessary as a result of changed circumstances; to confirm that regulations are both compatible with each other and not duplicative or inappropriately burdensome in the aggregate; to ensure that all regulations are consistent with the President's priorities and the principles set forth in this Executive Order, within applicable law; and to otherwise improve the effectiveness of existing regulations."
To carry out these reviews, on August 21, 2002, OSHA asked the public for comments on all issues raised by these provisions (67 FR 54103). Specifically, OSHA requested comments on the impacts of the rule on small businesses; the benefits and utility of the rule in its current form and, if amended, in its amended form; the continued need for the rule; the complexity of the rule; and whether, and to what extent, the rule overlaps, duplicates, or conflicts with other Federal, State, and local government rules. OSHA also asked for comments on new developments in technology, economic conditions, or other factors affecting the ability of covered firms to comply with the standard. Furthermore, OSHA asked for comments on alternatives to the rule that would minimize significant impacts on small businesses, while achieving the objectives of the Occupational Safety and Health Act.

OSHA accepted written comments from August 21, 2002 through November 19, 2002. All documents and comments received relevant to the review and documents discussed in this report are available at the OSHA Docket Office, Docket No. S204A (now Docket No. OSHA-2007-0012), Technical Data Center, Room N-2625, U.S. Department of Labor, 200 Constitution Avenue, N.W., Washington, DC 20210, Telephone (202) 693-2350, http://www.regulations.gov

1.2 Overview of Protective Systems Guarding Against Cave-Ins

Most accidents involving excavations or trenching are the result of soil cave-ins. There are three basic types of systems used to protect workers from the danger of cave-ins: sloping, shielding, and shoring. Although the concept behind each system is relatively simple, differences in soil types and other job-related factors make the selection and implementation of an appropriately designed protective system a matter requiring judgment and qualifications.

The simplest manner of controlling cave-ins is to slope the walls of the excavation at an angle such that soil does not roll into the excavation. The degree of the sloping angle needed depends on the stability of the soil at the site. In more stable soils, the slope can be relatively steeper than in less stable soils and still be effective. Sloping must be greater if the areas near the excavation are subject to heavy loads (e.g., soil piles, vehicles).

Trench shields do not prevent cave-ins. Instead, they protect employees from cave-ins that might occur by providing sheltered space where employees may work. A typical shield consists of two steel plates separated by structural members to form a box open at the top, bottom, and both ends. The box is lowered into the trench so that the steel plates face the trench's side walls. Employees then climb into the protected area defined by the steel plates. As the work progresses, the box is dragged along the bottom of the trench by a chain or cable suspended from a backhoe above the ground.

Shoring systems are structures made of wood or metal members that press tightly against an excavation side wall to brace and support the sidewalls and thereby prevent cave-ins. Aluminum hydraulic shores consist of two vertical members that support opposite sides of a trench and at least one connecting horizontal member containing hydraulic fluid that is pumped up to exert pressure on the vertical members. Timber shoring achieves similar support but is constructed out of timbers at the excavation site based on job-specific requirements.

1.3 Regulatory History

Trenching and excavation in construction were first regulated in 1969. For almost two decades, trenching and excavation standards were discussed, reviewed, and subject to technical amendments. Following a public hearing and public comments, OSHA issued a new construction standard for excavation in 1989. The important developments leading to the current Excavations Standard are as follows.

In 1969, Congress amended the Contract Work Hours Standards Act (40 U.S.C. 327 et seq.) by adding a new section 107 (40 U.S.C. 333) to provide employees in the construction industry with a safer work environment and to reduce the frequency and severity of construction accidents and injuries. The amendment, commonly known as the Construction Safety Act (Pub. L. 91-54; Aug. 9, 1969), provided occupational safety and health standards for employees in the building trades and construction industry in Federal and federally-financed and federally-assisted construction projects.

In 1971, the Secretary of Labor issued Safety and Health Regulations for Construction in 29 CFR part 15185 under the Contract Work Hours and Safety Standards Act. Included in these regulations were safety standards for trenching and excavation. OSHA adopted the trenching and excavation requirements contained in the Construction Safety Act standard as an OSHA standard in 1971.

OSHA made several technical amendments to the trenching and excavations standards, codified in Subpart P, in 19726, after review by the Advisory Committee on Construction Safety and Health (ACCSH) and rulemaking.

Responding to continuing complaints concerning the adequacy of the standards in Subpart P, OSHA engaged the National Bureau of Standards (NBS) in 1976 to study the compatibility of the technical provisions in the standard with actual construction practices. During 1979 and 1980, six NBS reports were issued after extensive review and public discussion of recommendations. Industry sponsored a series of workshops during 1981 to discuss ways of implementing the NBS recommendations. NBS prepared final recommendations for technical changes to the standard incorporating comments from the workshops.

In 1982, OSHA developed proposed changes to the standard to address continuing excavation-related accidents, compliance problems, and public requests to update the standards. The proposal was modified to reflect review by the ACCSH, and an NPRM was published in April 1987 in the Federal Register7. The proposal updated the existing standard to simplify many of the existing provisions, add and clarify definitions, eliminate duplicate provisions and ambiguous language, and give employers added flexibility in providing protection for employees. In addition, the standard provided several new appendices. One appendix provided a consistent method of soil classification. Others provided sloping and benching requirements, pictorial examples of shoring and shielding devices, timber tables, hydraulic shoring tables, and selection charts that provide a graphic summary of the requirements contained in the standard. A public hearing was convened in October 1987.

On October 31, 1989, after receiving comments on its proposed standards, holding a public hearing, consulting with the ACCSH, and examining the costs of compliance for the construction industry, OSHA issued a final standard for excavation and trenching8. An amendment promulgated in 1994 provided that walkways crossing over excavations deeper than six feet must be supplied with guardrails9.

1.4 Requirements of the Excavations Standard

OSHA has published a number of documents that describe the provisions of the Excavations Standard for employers and employees in construction10. The standard applies to all open excavations made in the earth's surface, which includes trenches.

Protective Systems. To prevent employee exposure to cave-ins, the standard requires sloping or benching the sides of all excavations, supporting the sides of the excavation (shoring), or placing a shield between the side of the excavation and the work area. To address the complexities of designing a protective system based on the many variables that an employer can encounter, the standard provides several different methods and approaches, including four for sloping and four for shoring, including the use of shields. The standard does not require the installation and use of a protective system when an excavation is made entirely in stable rock, or is less than five feet deep and a competent person has examined the ground and found no indication of a potential cave-in.

If sloping is used as the protective system, the employer has the option of using a predetermined slope with an angle not steeper than one and one-half horizontal to one vertical (34 degrees measured from the horizontal). These slopes must be excavated to form configurations that are in accordance with those for Type C soil found in Appendix B of the standard. A slope of this gradation or less is considered safe for any soil type. Another option is to determine slopes and configurations using Appendices A and B. This approach allows the employer to determine the maximum slope based on site-specific variables.

Another design method that applies to both sloping and shoring allows the employer to use tabulated data, such as tables and charts approved by a professional engineer, to design the excavation. These data must be in writing and must include sufficient explanatory information to enable the user to make a selection, including the criteria for determining the selection and limits of the data. A copy of the information must be kept at the worksite during construction of the protective system. Upon completion of the system, the data may be stored away from the job site, but must be made available to the Assistant Secretary of Labor upon request. A final option allows an employer to use a registered professional engineer to design the sloping or benching system based on professional judgment.

The standard allows an employer to use shoring or a trench box or shield that is either designed or approved by a registered professional engineer or is based on tabulated data prepared or approved by a registered engineer. Timber, aluminum, or other suitable material may be used. The standard permits the use of a trench shield as long as the protection it provides is equal to or greater than the protection that would be provided by the appropriate shoring system. The requirements for trench boxes and shields allow employers more flexibility in design, but impose an obligation to follow manufacturer's instructions for pre-made boxes and shields once a design has been chosen.

Adjacent Structures. The employer must provide support systems, such as shoring, bracing, or underpinning, to ensure the stability of adjacent structures. Excavation below the level of a base or footing of any foundation or retaining wall is prohibited unless a support system, such as underpinning, is provided; the excavation is in stable rock; or a registered engineer determines that the structure is sufficiently removed from the excavation and the excavation will not pose a hazard to employees. The standard prohibits excavations under sidewalks unless an appropriately designed support system is provided.

Installation and Removal. The standard provides procedures for the protection of employees during the installation and removal of protective systems. The employer is also responsible for the safe condition of materials and equipment used for protective systems.

Materials and Equipment. The employer must ensure that materials and equipment are free from damage or defects, are used and maintained according to manufacturer's specifications, and are periodically inspected by a competent person. Unsafe materials and equipment must be removed from service.

Falls and Equipment. Employers must protect employees from secondary hazards by meeting the following requirements: keeping materials that might fall or roll into an excavation from the edge or install a retaining device; providing warning systems to alert operators of the edge of an excavation; removing loose soil or rock or installing barricades or their equivalent; prohibiting employees from working on faces below other workers unless adequately protected from falling equipment; and prohibiting employees under loads that are handled by lifting or digging equipment.

Water Accumulation. The standard prohibits employees from working in excavations where water has accumulated unless adequate protection has been taken. Water removal equipment must be monitored to ensure proper use. Diversion ditches or dikes must be used for prevention or drainage of water accumulation and must be inspected by a competent person after heavy rains.

Hazardous Atmospheres. The standard requires that a competent person must test excavations greater than four feet in depth or ones where oxygen deficiency or a hazardous atmosphere exist, before an employee can enter the excavation. If hazardous conditions exist, personal protective equipment must be provided and the conditions must be reduced to acceptable levels and periodically monitored. Emergency equipment must be provided, readily available, and attended. Harnesses and lifelines are required for employees entering bell-bottom pier holes and similar deep and confining excavation. An observer must be present to ensure that the lifeline is working properly and to maintain communication with the employee.

Access and Egress. The standard requires the employer to provide safe access and egress to all excavations. For trenches four feet or deeper, the standard requires adequate means of exit, such as ladders, steps, and ramps, at 25 foot intervals. If structural ramps are used by employees, a competent person must design them, or, if for vehicle use, the competent person must be qualified in structural design.

2. Industry Profile, Trends, and Issues

This chapter characterizes the industry sectors affected by the Excavations Standard and how they have changed since the standard's revision in 1989. Section 2.1 first provides background information on trenching and excavation activities and when they are necessary. Section 2.2 then identifies affected industry sectors. Section 2.3 characterizes the economic performance of these sectors since 1989. Finally, Section 2.4 discusses technological advances since 1989.

2.1 Background

Most types of construction require some excavation or trenching work for foundations, footings, or utilities. Excavations are necessary for foundations and footings as part of both building and non-building construction projects11. Trenches are narrow excavations and are necessary for installation or repair of water and sewer pipes, gas lines, electrical conduit, or other underground conduits or cables.

Installation of utilities accounts for the majority of trenching activities. The trenches for sewer lines and water lines present the greatest concern for cave-ins because of the depth of these excavations. Sewer lines are typically installed at depths of eight to 15 feet, with some installations as deep as 40 feet. Water lines are typically installed at depths of four to five feet, with some deeper installations in colder climates to prevent freezing. Gas lines, electric, telephone, and other conduits and cables tend to be placed in shallow trenches of about two feet deep.

Most new building construction projects require excavation for foundations and basements. The scale of these excavations ranges from basements for single family homes to city block excavations for major urban buildings. Heavy construction projects, such as for highways, bridges, dams, and sewage treatment plants, also require excavation work. Excavations for these types of projects vary widely in their size.

2.2 Industry Sectors Affected by the Standard

This section identifies and discusses the industry sectors affected by the Excavations Standard in terms of the Standard Industrial Classification (SIC) system12.

Affected Sectors in the Construction Industry

The vast majority of excavation and trenching work is performed by the construction industry. Firms that engage in excavation and trenching operations are primarily construction contractors. These firms are classified as general building contractors (SIC group 15), heavy construction contractors (SIC group 16), or special trade contractors (SIC group 17). Other industries, however, may utilize their own construction crews for trenching or excavation projects. For example, electric and gas utilities may use their own labor force for the trenching required for installation of pipes or cables. Public employees, primarily municipal public works departments, also engage in trenching or excavation projects. Exhibit 2-1 lists the four-digit SIC code industries that account for the bulk of trenching and excavation work.

Building construction requires two types of excavations: an excavation for the foundation and trenches for water, sewer, and other utility hookups. Building excavations are generally dug either by building contractors (SIC group 15) themselves, or by excavation contractors (SIC group 1794). Utility hookups are commonly performed by plumbing contractors (SIC 1711).

Exhibit 2-1
Relevant Construction Industry SIC Codes (15, 16, and 17)

1521 General Contractors-Single-Family Houses
1522 General Contractors-Residential Construction not elsewhere classified
1531 Operative builders
1541 General Contractors-Industrial Buildings and Warehouses
1542 General Contractors-Nonresidential Buildings, Other than Industrial Buildings and Warehouses
1611 Highway and Street Construction, Except Elevated Highways
1622 Bridge, Tunnel, and Elevated Highway Construction
1623 Water, Sewer, Pipeline, and Communications and Power Line Construction
1629 Heavy Construction, NEC
1711 Plumbing, Heating, and Air-Conditioning
1721 Painting and paper hanging
1731 Electrical Work
1741 Masonry and other stonework
1751 Carpentry work
1761 Roofing, siding, and sheet metal work
1771 Concrete Work
1781 Water well drilling
1791 Structural steel erection
1794 Excavation Work
1795 Wrecking and demolition work
1799 Special Trade Contractors, NEC

Excavations for non-building projects include trenches for sewers, water mains, pipelines, and highway drainage systems. Trenching work is done primarily by so-called "utility contractors" (SIC 1623). Other heavy construction contractors as well as some special trade contractors (primarily 1794, excavation contractors, and 1711, plumbing contractors) also do utility work. Excavations for other types of non-building projects are usually performed by heavy construction general contractors (SIC group 16), or by excavation contractors (SIC 1794). Some special purpose excavations such as for outdoor swimming pools are done by contractors classified in SIC 1799 (Special Trade Contractors, N.E.C.).

Affected Non-Construction Industry Sectors

A number of industry sectors outside of the construction industry also conduct trenching and excavation activities on occasion. Exhibit 2-2 lists the SIC code and industry description for non-construction industries that are believed to engage in some excavation and trenching activities and are covered by the Standard.
Exhibit 2-2
Non-Construction Industry SIC Codes Conducting Some Excavation Activity

0781 Landscape Counseling and Planning
0782 Lawn and Garden Services
1081 Metal Mining Services
1311 Crude Petroleum and Natural Gas
4813 Telephone Communications, Except Radiotelephone
4911 Electric Services
4924 Natural Gas Distribution
4925 Mixed, Manufactured, or Liquefied Petroleum Gas Production and/or Distribution
4931 Electric and Other Services Combined
4932 Gas and Other Services Combined
4935 N/A
4941 Water Supply
5093 Scrap and Waste Materials
7353 Heavy Construction Equipment Rental and Leasing
7389 Business Services, NEC
7699 Repair Shops and Related Services, NEC
8221 Colleges, Universities, and Professional Schools
8222 Junior Colleges and Technical Institutes
8711 Engineering Services
8713 Surveying Services
9199 General Government, NEC
9511 Air and Water Resource and Solid Waste Management
9512 Land, Mineral, Wildlife, and Forest Conservation
9621 Regulation and Administration of Transportation Programs
9631 Regulation and Administration of Communications, Electric, Gas, and Other Utilities
Source: ICF analysis of IMIS Database. See Chapter 3.

Sectors Most Affected by Standard

Although numerous construction industry sectors and non-construction industry sectors are affected by the standard, this study focuses primarily on 12 sectors within the construction industry that collectively account for approximately 89 percent of excavation and trenching fatalities between 1990 and 2000 (as discussed in Chapter 3).
  • 1521: General Contractors - Single-Family Houses
  • 1542: General Contractors - Nonresidential Buildings, Other than Industrial Buildings and Warehouses
  • 1611: Highways and Street Construction, Except Elevated Highways
  • 1622: Bridge, Tunnel, and Elevated Highway Construction
  • 1623: Water, Sewer, Pipeline, and Communications and Power Line Construction
  • 1629: Heavy Construction, NEC
  • 1711: Plumbing, Heating, and Air-Conditioning
  • 1731: Electrical Work
  • 1771: Concrete Work
  • 1794: Excavation Work
  • 1795: Wrecking and demolition work
  • 1799: Special Trade Contractors, NEC
The remaining construction and all non-construction SIC codes are excluded from the analysis because they engage in excavation and trenching on only an occasional basis. Because excavation and trenching activities are such a small portion of the activities of other industry sectors, it could be misleading to include them in the analysis, and it would be hard to evaluate trends and estimate economic impacts attributable to the standard.

2.3 Economic Performance of Industry Sectors

Available statistics do not permit the direct measurement of excavation and trenching activities. Nevertheless, growth in these activities since the Excavations Standard was revised in 1989 can be surmised based on the following:
  • The construction industry as a whole has grown during the past two decades. Overall, the value of construction put in place in the United States has risen between 1980 and 2000, both in constant and nominal terms (see Exhibit 2-3). In nominal dollars, the value of the construction industry has risen from less than $300 billion in 1980 to over $800 billion in 2000, while the value (in 1996 dollars) has risen from just under $500 billion in 1980 to approximately $700 billion in 2000.
Exhibit 2-3
Value of Construction Put in Place in the U.S. (1980-2000)
Exhibit 2-3: Value of Construction Put in Place in the U.S. (1980-2000)
Text version of Chart

Chart Title: Exhibit 2-3: Value of Construction Put in Place in the U.S. (1980-2000)
Chart Type: Line graph
Chart Elements: 2 lines, one for Constant Dollars and one for Nominal Dollars, showing the value in Billions ($) for each year from 1980-2000.

Chart Data:
  • Constant Dollars (In Billions):
    • 1980 = $464.144
    • 1981 = $455.260
    • 1982 = $423.729
    • 1983 = $465.073
    • 1984 = $534.557
    • 1985 = $567.689
    • 1986 = $588.804
    • 1987 = $585.103
    • 1988 = $583.396
    • 1989 = $579.583
    • 1990 = $560.802
    • 1991 = $503.711
    • 1992 = $533.322
    • 1993 = $544.285
    • 1994 = $574.256
    • 1995 = $570.188
    • 1996 = $615.797
    • 1997 = $632.680
    • 1998 = $664.244
    • 1999 = $692.281
    • 2000 = $706.899
  • Nominal Dollars (In Billions):
    • 1980 = $273.936
    • 1981 = $289.070
    • 1982 = $279.332
    • 1983 = $311.887
    • 1984 = $370.190
    • 1985 = $403.416
    • 1986 = $433.454
    • 1987 = $446.643
    • 1988 = $462.012
    • 1989 = $477.502
    • 1990 = $476.778
    • 1991 = $432.592
    • 1992 = $463.661
    • 1993 = $491.033
    • 1994 = $539.193
    • 1995 = $557.818
    • 1996 = $615.900
    • 1997 = $653.429
    • 1998 = $704.724
    • 1999 = $763.786
    • 2000 = $815.414
  • The number of firms conducting excavation and trenching activities has grown since the revision of the Excavations Standard.

  • As measured by the Census Bureau, the number of employees in the 12 most affected industry sectors has increased by 23 percent, from 3,037,872 employees in 1990 to 3,741,386 employees in 1997.

  • The total number of firms in the 12 most affected industries has increased 51 percent from 292,996 in 1989 to 443,686 in 1998.

  • The number of firms in individual sectors increased for 11 of the 12 SIC codes (The exception, SIC 1622, is discussed in greater detail in Section 2.3.2.).

  • Exhibit 2-4 presents the number of firms and employees by SIC code for the 12 construction SIC codes of interest.
Exhibit 2-2
Non-Construction Industry SIC Codes Conducting Some Excavation Activity

SIC Number of Firms Number of Employees
1989 1998 Change 1990 1997 Change
1521 56,532 136,912 142% 282,172 476,363 69%
1542 18,299 30,309 66% 375,184 446,056 19%
1611 8,836 10,707 21% 213,172 229,796 8%
1622 911 881 -3% 39,454 36,559 -7%
1623 8,074 10,774 33% 170,830 220,606 29%
1629 10,730 14,512 35% 274,805 281,322 2%
1711 73,459 87,654 19% 644,513 790,052 23%
1731 53,761 65,093 21% 528,264 646,860 22%
1771 22,225 30,710 38% 198,640 244,632 23%
1794 16,198 23,210 43% 101,298 112,025 11%
1795 845 1,336 58% 11,993 17,737 48%
1799 23,126 31,588 37% 197,547 239,378 21
Total 292,996 443,686 51% 3,037,872 3,741,386 23%
Source: 1989 Figures: "Data by Enterprise," U.S. Census Bureau; 1998 Figures: Small Business Administration (SBA) Office of Advocacy information obtained from the U.S. Census Bureau; Percent Change: ICF analysis of Census Bureau and SBA information.

2.4 Developments in Technology

Traditional open-cut trenching methods require the use of protective systems, such as shoring and trench boxes, to prevent cave-ins. There has been incremental refinement in these manufactured systems since the enactment of the revised standard in 1989. For example, shoring has become less expensive, lighter, and more maneuverable. As manufactured systems have improved, the use of site-constructed timber shoring systems has declined.

The most significant technological development, however, has been the emergence of "trenchless technologies." This term applies to a wide range of construction methods used to install or repair pipes and cables without traditional open-cut trenching operations13. As discussed in more detail below, these methods typically involve some type of horizontal drilling, tunneling, or ramming. While open-cut trenching methods still predominate, the use of trenchless technologies has increased steadily since 1989, particularly in more highly-developed areas.

Trenchless operations substantially reduce the size of the excavation required at a particular job, thereby reducing the risk of killing or injuring workers or the public in construction-related accidents. Trenchless methods cost more than open-cut methods for most jobs, but they can be quite cost-effective for some jobs, particularly when the costs of disrupted activities (e.g., routine commerce) are considered, or when open-cut trenches would be difficult or costly to implement. For example, digging an open trench in a congested urban area can be expensive because a crew typically must dig around existing utilities and protect adjacent pavement and structures from collapse. Additionally, sidewalks, pavement, bricks, sod, and other surfaces must be repaired or replaced after the trench is closed. Most of the direct costs of the trenching operations are borne by the utility, but the community must bear the cost of disruption, delay, or damage - including traffic disturbances and delays, lost revenue to businesses, and lost tax dollars to government. Trenchless methods, by minimizing disruption, may reduce total costs in such instances.

Among the more common trenchless methods are the following:
  • Auger boring, one of the oldest trenchless methods, is still widely used for short distances and small changes in grade (e.g., under highways or railroad tracks). Auger boring works by using a powerful machine to drill through the earth, installing sections of pipe as the bore progresses and carries spoil out of the hole. Auger boring machines are not equipped with guidance systems, but are capable of cutting through hard rock and are relatively low-cost.

  • Horizontal Directional Drilling (HDD) works by using a rotating drill to break the ground, while another piece of equipment is used to enlarge the hole. At the surface, steering equipment is used to install pipes, conduits, or cables. Location, depth, and position are also monitored on the surface using highly accurate electronic tracking equipment. HDD equipment is generally used for installations where larger and longer piping is required, and for replacing water lines in urban and residential areas.

  • Pipe ramming uses pneumatic piercing tools and an air compressor to pound equipment into the ground. The material that is being installed is either pulled behind the equipment or is pulled through the completed hole. Soil in the casing is generally removed with compressed air or water. Most of the pneumatic tools cannot be steered, but some models use radio transmitters to track progress with an electronic locator. This method is commonly used to drill under sidewalks and driveways.

  • Pipe bursting is the most commonly used trenchless method for the replacement of existing pipes. The equipment drives through a section of existing pipe, fragmenting the pipe with a hammering action. Replacement pipe, attached to the rear of the equipment, is pulled into place using a cable, chain, or rod that is attached to the pulling device. Pipe bursting is used when the existing pipe is brittle cast iron, vitrified clay, unreinforced concrete, asbestos cement, or plastic. This method is limited to smaller pipes, although the replacement pipe can be larger than the existing pipe.

  • Microtunneling begins by creating a hole using a cutting shield, which forms a continuous tunnel lining. Laser-guided, remote-controlled equipment pushes sections of pipe into the hole and through the ground while soils are removed with augers. Equipment and mobilization costs are high, making this the most expensive trenchless procedure. Microtunneling is most common in Germany and Japan.

  • Vibratory plowing (the use of a vibratory plow), either a walk behind or ride-on machine, pulls a vertical plow blade through the ground, cutting through soil and vegetation with a minimum of surface disturbance, typically for burying wire, cable, fiber optics, conduit, and water or gas pipe. The ground opens around the plow and closes behind it or leaves a small slit to be back filled. A hydraulic motor driving rotating weights on the plow causes the blade to vibrate as it is pulled through the earth. Plow configuration is matched to the product to be buried. Vibration and ground speed are controlled by the operator to maximize production in various conditions. Some plows pull the material being buried through the earth behind the blade with a special attachment. Others feed the material into the ground through a chute at the back of the blade.
Trenchless methods have some disadvantages, including their own risks to workers and the public. Most notably, operators cannot always see what lies in the way and, consequently, underground utility lines may be cut. Such accidents can result in injuries or deaths depending on the circumstances, in addition to the added expense of repairing the damaged lines. Another risk is that, after construction, unseen voids may be left behind, which could lead to a collapse that could cause physical injuries or property damage.

Several related technological advances have improved the quality and decreased the cost of trenchless methods. These include newer, more precise guidance electronics; new pipe materials (such as high-density polyethylene [HDPE]) that are tough but flexible; cured-in-place pipe lining systems; and new pipe bursting tools. In addition, a variety of new technologies have been developed for repairing pipes. Robotic systems, for example, can make point repairs using special attachments for repairing leaks. Also, more effective materials are available to seal pipe repairs, such as acrylmide, acrylate, urethane gel, and polyurethane foam.

3. Fatalities

This chapter estimates the number and rate of excavation-related fatalities to help evaluate the effectiveness of the Excavations Standard with respect to preventing fatalities. Except where noted, all fatality data have been drawn from OSHA's Integrated Management Information System (IMIS) database14. The analysis of fatalities begins at the national level before considering individual industries and causes (i.e., types of accidents).

3.1 National Fatalities and Trends

During the eleven-year period 1990-2000, accidents involving excavations resulted in an annual average of 70 fatalities, or a total of 771 for the period as a whole. The actual number of fatalities each year varied within the range of 59-81. Exhibit 3-1 reports the number of fatalities occurring in each year.
Exhibit 3-1
Number of Trenching and Excavation Fatalities

Year Fatalities
1990 76
1991 72
1992 72
1993 59
1994 74
1995 61
1996 62
1997 72
1998 67
1999 81
2000 75
Total 771
Average 70
Source: ICF analysis of IMIS database.

In 1987, prior to OSHA's 1989 revision of the Excavations Standard, OSHA estimated the annual average number of excavation-related fatalities at 9015. Relative to this figure, the post-rule estimate of 70 represents a 22% reduction in the number of fatalities related to excavation since the promulgation of OSHA's revised standard. Moreover, this 22% reduction has been achieved as construction activity increased by 20% in real terms over this period.

Although the number of excavation-related fatalities per year remained fairly level during the 1990-2000 period, as shown in Exhibit 3-2, these data do not reflect the increase in annual construction activity that occurred during the same period. To gauge fatalities relative to the level of construction, the study divided each year's number of fatalities by the value of construction put in place for the same year16, thereby yielding a fatality rate. The fatality rate did decline over the period, as shown in Exhibit 3-3. In other words, although the annual number of fatalities remained fairly constant, the fatality rate decreased due to an increase in construction activity.
Exhibit 3-2
Number of Fatalities, 1990-2000
Exhibit 3-2: Number of Fatalities, 1990-2000
Text version of Chart

Chart Title: Exhibit 3-2: Number of Fatalities, 1990-2000
Chart Type: Line graph
Chart Elements: 11 - One point for each year showing the number of fatalities

Chart Data:
  • 1990 = 76
  • 1991 = 72
  • 1992 = 72
  • 1993 = 59
  • 1994 = 74
  • 1995 = 61
  • 1996 = 62
  • 1997 = 72
  • 1998 = 67
  • 1999 = 81
  • 2000 = 75
Source: ICF analysis of IMIS database

Exhibit 3-3
National Fatalities per Billion Dollars of Construction Value Put in Place, 1990-2000
Exhibit 3-3: National Fatalities per Billion Dollars of Construction Value Put in Place, 1990-2000
Text version of Chart

Chart Title: Exhibit 3-3: National Fatalities per Billion Dollars of Construction Value Put in Place, 1990-2000
Chart Type: Line graph
Chart Elements: 11 - One point for each year showing the number of fatalities

Chart Data:
  • 1990 = 0.14
  • 1991 = 0.15
  • 1992 = 0.14
  • 1993 = 0.11
  • 1994 = 0.13
  • 1995 = 0.11
  • 1996 = 0.10
  • 1997 = 0.11
  • 1998 = 0.10
  • 1999 = 0.12
  • 2000 = 0.11
Source: ICF analysis of IMIS database and economic census data

3.2 Fatalities by Industry

The 1990-2000 data show that excavation fatalities occur in numerous industries but are primarily concentrated in a relatively few. Twelve industries, all of which fall within the construction sector, account for approximately 89 percent of excavation-related fatalities. These industries include the following SIC codes (listed in order of the greatest to the least total number of fatalities over the 11-year period)17:
  • 1623: Water, Sewer, Pipeline, Communications, and Power Line
  • 1794: Excavation Work
  • 1711: Plumbing, Heating, and Air Conditioning
  • 1629: Heavy Construction
  • 1542: General Contractors, Non-Residential, Non-Industrial
  • 1611: Highway and Street Construction
  • 1521: General Contractors, Single Family Homes
  • 1771: Concrete Work
  • 1799: Special Trade Contractors
  • 1622: Bridge, Tunnel, and Elevated Highway
  • 1731: Electrical Work
  • 1795: Wrecking and Demolition Work
Exhibit 3-4 shows the distribution of fatalities across these 12 industries as well as the "other" remaining industries. As illustrated in the graph, SIC 1623 (Water, Sewer, Pipeline, Communications, and Power Line) reports the highest number of excavation-related fatalities, at more than twice that of the industry with the second highest total fatalities (SIC 1794, Excavation Work). SIC 1623 conducts a substantial amount of trenching activity.
Exhibit 3-4
Fatalities by Industry, 1990-2000
Exhibit 3-4: Fatalities by Industry, 1990-2000
Text version of Chart

Chart Title: Exhibit 3-4: Fatalities by Industry, 1990-2000
Chart Type: Bar graph
Chart Elements: 13 - One bar for each SIC code showing the Total Fatalities

Chart Data:
  • SIC 1623 = 265
  • SIC 1794 = 117
  • SIC 1711 = 84
  • SIC 1629 = 51
  • SIC 1542 = 31
  • SIC 1611 = 31
  • SIC 1521 = 20
  • SIC 1771 = 19
  • SIC 1799 = 15
  • SIC 1622 = 12
  • SIC 1731 = 12
  • SIC 1795 = 11
  • Other = 103
Source: ICF analysis of IMIS database

The ranking of these industries changes somewhat when based on the fatality rate per 1,000 employees working within the designated SIC code18. Nevertheless, as shown in Exhibit 3-5, SIC 1623 continues to stand out with the number of fatalities substantially higher than the other key industries.
Exhibit 3-5
Average Fatality Rate by SIC per 1,000 Employees, 1990-1997
Exhibit 3-5: Average Fatality Rate by SIC per 1,000 Employees, 1990-1997
Text version of Chart

Chart Title: Exhibit 3-5: Average Fatality Rate by SIC per 1,000 Employees, 1990-1997
Chart Type: Bar graph
Chart Elements: 11 - One bar for each SIC code showing the Fatality Rate

Chart Data:
  • SIC 1623 = 0.1416
  • SIC 1794 = 0.0918
  • SIC 1622 = 0.0281
  • SIC 1629 = 0.0177
  • SIC 1771 = 0.0154
  • SIC 1611 = 0.0122
  • SIC 1542 = 0.0076
  • SIC 1711 = 0.0045
  • SIC 1799 = 0.0042
  • SIC 1731 = 0.0031
  • SIC 1521 = 0.0027
Source: ICF analysis of IMIS database and economic census data

As shown in Exhibit 3-6, however, the fatality rate for SIC 1623 has a decreasing trend from 1990-1997 (which is not the case for SIC 1794 and some of the other industries).
Exhibit 3-6
Fatality Rate for SIC Code 1623, 1990-1997
(Water, Sewer, Pipeline, Communications, and Power Line)
Exhibit 3-6: Fatality Rate for SIC Code 1623, 1990-1997 (Water, Sewer, Pipeline, Communications, and Power Line)
Text version of Chart

Chart Title: Exhibit 3-6: Fatality Rate for SIC Code 1623, 1990-1997 (Water, Sewer, Pipeline, Communications, and Power Line)
Chart Type: Line graph
Chart Elements: 8 - One point for each year showing the Fatality Rate per 1,000 employees

Chart Data:
  • 1990 = 0.15
  • 1991 = 0.15
  • 1992 = 0.22
  • 1993 = 0.19
  • 1994 = 0.11
  • 1995 = 0.1
  • 1996 = 0.13
  • 1997 = 0.09
Source: ICF analysis of IMIS database and economic census data

3.3 Fatalities by Cause of Death

Excavation fatalities may result from a variety of accident types, including cave-ins, machine accidents, falling objects, electrocution, car accidents, explosions or fires, falls, drowning, and asphyxiation due to noxious fumes. Exhibit 3-7 shows the relative proportion for each cause of death for the 1990-2000 period. As illustrated in the graph, approximately half of all excavation-related fatalities (approximately 48 percent) result from cave-ins.
Exhibit 3-7
Distribution of Fatalities by Cause of Death, 1990-2000
Exhibit 3-7: Distribution of Fatalities by Cause of Death, 1990-2000
Text version of Chart

Chart Title: Exhibit 3-7: Distribution of Fatalities by Cause of Death, 1990-2000
Chart Type: Pie Chart
Chart Elements: 10 - One piece for each cause of death showing the percentage

Chart Data:
  • Cave-in = 48%
  • Machine Accident = 23%
  • Object falling = 9%
  • Electrocution = 7%
  • Car Accident = 2%
  • Explosion/Fire = 2%
  • Fall = 3%
  • Drowning = 1%
  • Asphyxiation - Noxious Fumes = 1%
  • Other = 5%

4. Compliance with the Standard

This chapter evaluates compliance with the Excavations Standard at 29 CFR, Subpart P, §§1926.650-652 and appendices A-F, by evaluating violation data contained in OSHA's Integrated Management Information System (IMIS) database19. OSHA does not require employers to report an accident unless three or more employees have been hospitalized, an amputation has occurred, or a fatality has occurred. Therefore, only limited data are available on accidents that do not involve fatalities. Consequently, this study examines compliance by looking at accidents involving fatalities20.

Excavation accident reports and news accounts suggest, nearly universally, that compliance with existing safety standards would have prevented the accidents being described21. This hypothesis is largely supported by violation data contained in IMIS. These data indicate that OSHA found violations of the Excavations Standard in approximately 80 percent of the 771 cases of excavation-related fatalities that occurred between 1990 and 2000. While the reported data did not specify any violations for almost 20 percent of the reported fatalities, OSHA does not believe this implies full compliance with the Excavations Standard in these cases22.

The analysis of compliance first considers the types of violations associated with fatalities. It then reviews related information on monetary penalties associated with the violations.

4.1 Compliance Violations

This study found 1,149 violations associated with the 771 excavation fatalities reported during 1990-2000. (Many fatalities are associated with multiple violations.) Of these 1,149 violations, 565 violations (approximately 50 percent) are reported to have been a contributing factor to the corresponding fatal accident (see Exhibit 4-1)23. In fact, a key finding of this study is that OSHA has identified one or more compliance violations as a contributing factor in over 73 percent of the 771 fatalities examined. As explained above and in footnote 22, OSHA believes the true percentage is even higher. It seems reasonable to conclude, therefore, that the current standard, when met, is protective of worker safety. This does not imply, however, that the standard need not be modified, as it may be possible to revise the standard in a manner that would increase compliance.
Exhibit 4-1
Violations and Fatalities

Fatalities 771
Fatalities with reported violations 624
Violations associated with fatalities 1,149
Violations identified as contributing to fatalities 565

To help evaluate the level of compliance, and the importance of compliance with individual provisions of the Excavations Standard, Exhibit 4-2 summarizes and classifies each provision in the standard with respect to the number of violations associated with, and contributing to, fatalities during the 1990-2000 period. Exhibit 4-3 summarizes this information graphically.
Exhibit 4-1
Violations and Fatalities

Section and Description Violations Associated with Fatalities Violations Contributing to Fatalities
1926.650 - Scope, application, and definitions 4 1
1926.651 - Specific Excavation Requirements
(a) Surface encumbrances 7 2
(b) Underground installations 23 9
(c) Access and egress 137 60
(d) Exposure to vehicular traffic 11 4
(e) Exposure to falling loads 11 4
(f) Warning system for mobile equipment 8 4
(g) Hazardous atmospheres 18 7
(h) Protection from hazards associated with water accumulation 36 19
(i) Stability of adjacent structures 36 19
(j) Protection of employees from loose rock or soil 158 68
(k) Inspections 253 142
(l) Walkways and guardrails 5 0
1926.652 - Requirements for Protective Systems
(a) Protection of employees in excavations 328 171
(b) Design of sloping and benching systems 22 12
(c) Design of support systems, shield systems, and other protective systems 19 5
(d) Materials and equipment 9 4
(e) Installation and removal of support 26 12
(f) Sloping and benching systems 3 3
(g) Shield systems 17 9

Exhibit 4-3
Fatality-Related Violations of the Excavation Standard, 1990-2000
Exhibit 4-3: Fatality-Related Violations of the Excavation Standard, 1990-2000
Text version of Chart

Chart Title: Exhibit 4-3: Fatality-Related Violations of the Excavation Standard, 1990-2000
Chart Type: Bar Graph
Chart Elements: 40 - Two bars for each excavation standard showing the number of fatalities

Chart Data:
 
  • Number of Violations Associated with Fatalities
    • 19260652 A = 328
    • 19260651 K = 253
    • 19260651 J = 158
    • 19260651 C = 137
    • 19260651 H = 36
    • 19260651 I = 36
    • 19260652 E = 26
    • 19260651 B = 23
    • 19260652 B = 22
    • 19260652 C = 19
    • 19260651 G = 18
    • 19260652 G = 17
    • 19260651 D = 11
    • 19260651 E = 11
    • 19260652 D = 10
    • 19260651 F = 8
    • 19260651 A = 7
    • 19260651 L = 5
    • 19260650 = 4
    • 19260652 F = 3
  • Number of Violations Associated with Fatalities
    • 19260652 A = 171
    • 19260651 K = 142
    • 19260651 J = 68
    • 19260651 C = 60
    • 19260651 H = 19
    • 19260651 I = 19
    • 19260652 E = 12
    • 19260651 B = 9
    • 19260652 B = 12
    • 19260652 C = 5
    • 19260651 G = 7
    • 19260652 G = 9
    • 19260651 D = 4
    • 19260651 E = 4
    • 19260652 D = 4
    • 19260651 F = 4
    • 19260651 A = 2
    • 19260651 L = 0
    • 19260650 = 1
    • 19260652 F = 3

As can be seen from Exhibit 4-3, the sections of the standard that account for the most violations in the dataset include sections 1926.652(a), 1926.651(k), 1926.651(j), and 1926.651(c). These requirements, which are stated in the adjacent text box, are quite fundamental: protect employees in excavation; inspect the site daily; protect employees from loose rock or soil; and provide access and egress. In contrast, far fewer violations occurred with respect to some of the more specific provisions of the Excavations Standard, such as design of sloping and benching systems, design of support systems and shield systems, and protection from hazardous atmospheres. The fact that most violations occur with respect to the standard's basic requirements (as opposed to its more specific provisions) suggests that fatalities may result more from a failure to understand the risks or the failure to apply any safety systems than from a failure to install safety systems correctly.

4.2 Penalties

The average monetary penalty reported by section of the standard is shown in Exhibit 4-4. The amount of the initial penalty may be reduced (to the amount of the "current penalty") if the violator contests the violation or the associated penalty. Note that zero dollar penalties are included in the calculation of the averages.

Since 1987, OSHA has had in place a special emphasis program on trenching and excavation. For example, OSHA IMIS (Internal Management Information System) data identify 1,382 inspections of excavating contractors during 2000. These inspections include both Federal and State Plan inspections in SIC 1794 (Excavation Work), the SIC with the highest concentration of excavation work. These inspections resulted in 2,205 citations that totaled $1,907,593 in penalties. Four hundred sixty-five (34%) of these inspections found no violations.
Most Common Fatality-Related Violations, 1990-2000

1926.652(a): Protection of employees in excavations.
(1) Each employee in an excavation shall be protected from cave-ins by an adequate protective system designed in accordance with paragraph (b) or (c) of this section except when:
    (i) Excavations are made entirely in stable rock; or
    (ii) Excavations are less than 5 feet (1.52m) in depth and examination of the ground by a competent person provides no indication of a potential cave-in.
(2) Protective systems shall have the capacity to resist without failure all loads that are intended or could reasonably be expected to be applied or transmitted to the system.

1926.651(k): Inspections.
(1) Daily inspections of excavations, the adjacent areas, and protective systems shall be made by a competent person for evidence of a situation that could result in possible cave-ins, indications of failure of protective systems, hazardous atmospheres, or other hazardous conditions. An inspection shall be conducted by the competent person prior to the start of work and as needed throughout the shift. Inspections shall also be made after every rainstorm or other hazard increasing occurrence. These inspections are only required when employee exposure can be reasonably anticipated.
(2) Where the competent person finds evidence of a situation that could result in a possible cave-in, indications of failure of protective systems, hazardous atmospheres, or other hazardous conditions, exposed employees shall be removed from the hazardous area until the necessary precautions have been taken to ensure their safety.

1926.651(j): Protection of employees from loose rock or soil.
(1) Adequate protection shall be provided to protect employees from loose rock or soil that could pose a hazard by falling or rolling from an excavation face. Such protection shall consist of scaling to remove loose material; installation of protective barricades at intervals as necessary on the face to stop and contain falling material; or other means that provide equivalent protection.
(2) Employees shall be protected from excavated or other materials or equipment that could pose a hazard by falling or rolling into excavations. Protection shall be provided by placing and keeping such materials or equipment at least 2 feet (.61 m) from the edge of excavations, or by the use of retaining devices that are sufficient to prevent materials or equipment from falling or rolling into excavations, or by a combination of both if necessary.

1926.65(c): Access and egress.
(1) Structural ramps.
    (i) Structural ramps that are used solely by employees as a means of access or egress from excavations shall be designed by a competent person. Structural ramps used for access or egress of equipment shall be designed by a competent person qualified in structural design, and shall be constructed in accordance with the design.
    (ii) Ramps and runways constructed of two or more structural members shall have the structural members connected together to prevent displacement.
    (iii) Structural members used for ramps and runways shall be of uniform thickness.
    (iv) Cleats or other appropriate means used to connect runway structural members shall be attached to the bottom of the runway or shall be attached in a manner to prevent tripping.
    (v) Structural ramps used in lieu of steps shall be provided with cleats or other surface treatments on the top surface to prevent slipping.
(2) Means of egress from trench excavations. A stairway, ladder, ramp or other safe means of egress shall be located in trench excavations that are 4 feet (1.22 m) or more in depth so as to require no more than 25 feet (7.62 m) of lateral travel for employees.

Exhibit 4-4
Average Monetary Penalties Associated with the Excavations Standard, 1990-2001

Standard Average Initial Penalty Average Current Penalty
19260650 $540 $340
19260651 A $12,607 $2,107
19260651 B $8,900 $7,778
19260651 C $4,813 $3,104
19260651 D $1,183 $487
19260651 E $8,867 $1,798
19260651 F $2,588 $2,323
19260651 G $2,101 $1,200
19260651 H $12,259 $4,907
19260651 I $4,247 $3,232
19260651 J $6,545 $4,354
19260651 K $5,685 $3,804
19260651 L $829 $797
19260652 A $15,014 $8,496
19260652 B $8,782 $5,493
19260652 C $9,628 $8,096
19260652 D $7,273 $7,075
19260652 E $3,259 $1,488
19260652 F $1,867 $933
19260652 G $12,956 $12,057
19260652 K $4,833 $2,833
This table omits penalties reported in IMIS if attributed to a subparagraph of the standard which can not be identified with certainty because of a typographical error in the IMIS data.

5. Cost Analysis

The objective of the "lookback" cost analysis is to assess the relative increase or decrease in the cost of required safety measures for excavation since 1990. If costs have increased substantially, then impacts on small businesses are likely to have increased over the period as well. Conversely, if safety-related costs have stayed constant or decreased in real terms, then impacts are not likely to have increased. The analysis and key findings are summarized in Section 5.1. Section 5.2 presents additional details on the comparison of costs.

5.1 Overview and Key Findings

The standard requires that walls and faces of all excavations or trenches should be guarded by a shoring system, safe sloping, or equivalent means of protection such as trench shields or trench boxes. This study estimates the 2001 cost of using the four most common types of protective systems: sloping, trench boxes, aluminum shoring, and timber shoring24. It then compares the current cost to the corresponding cost (inflation-adjusted) at the time the standard became effective in 199025. These findings are supplemented by research conducted on trends in the use of various types of safety equipment, including telephone discussions with members of government, trade associations, and vendors serving the trenching/excavation market.

The analysis finds that trench boxes, aluminum shoring, and the use of sloping were less expensive in 2001 (by about 10% in real dollars) than they were in 1990. Timber shoring may be more or less expensive today than previously, depending on the type and size of timbers used. In any event, however, timber shoring is used less frequently today than a decade ago26. Newer types of protective systems, including the various "trenchless" technologies, slide rail systems, and modular trench boxes, are being used with increasing frequency. Although the costs of these newer systems have not been examined for this study, it is reasonable to assume that each enjoys a net cost advantage over the older methods, at least in those situations where the newer systems are used.

The study concludes, therefore, that the protective systems available in 1990 (when the Excavations Standard was enacted) remain available today and, in fact, cost less in 2001 in real dollars. Furthermore, the entry into the marketplace of new types of protective systems has increased available options and likely has reduced the cost of meeting the standard.

5.2 Cost Analysis of Protective Systems

This section details the cost analysis of the four most common types of protective systems: sloping, trench boxes, aluminum shoring, and timber shoring. The analysis estimates and compares the current cost of each type of system to what the system cost when the Excavations Standard became effective in 1990. This approach implicitly assumes that firms would employ the same type of protective system today as a decade ago. In reality, as the relative costs of systems change, firms will tend to substitute the less expensive systems for the more costly ones. In addition, the analysis does not explicitly account for new technologies (e.g., trenchless technologies) that have, in fact, gained a share of the excavation safety market; these new technologies would not be used if they were not, on net, the most cost-effective option available for certain jobs. For both of these reasons, cost impacts are likely to be overstated by this study.

It is not always the case that cost is the driving factor in selecting a protective system. In some cases, site-specific or job-specific conditions may limit the available choices:
  • Sloping frequently is not an option for excavation or trenching work conducted in urbanized areas because roadways, sidewalks, or building foundations limit the width of the area that would need to be excavated.

  • When trenches will cross existing utility lines, trench boxes often cannot be used. Some form of shoring is typically used when pre-existing utilities are an issue.

  • Soil type also may prevent the selection of a particular safety measure (e.g., use of aluminum shoring is inappropriate in soils lacking internal cohesion).

  • Trench boxes may be infeasible or inappropriate for use in trenches that will remain open for prolonged periods. Trench boxes typically are dragged forward to the newer, working portions of a trench while the prior section (where work has just been completed) is quickly filled (after the trench box has left that section). The trench box generally should not be moved until the particular section of the trench containing the trench box is ready to be filled. Consequently, the heavy trench box is not typically used in cases where a trench will remain open long, except where the trench is short in length.
Nevertheless, these considerations are not new, so firms facing a restricted set of options today are no different than similarly situated firms in 1990. In these situations, where there is a reduced ability to select an alternative protective system, a comparison of current costs to 1990 costs is particularly appropriate.

5.2.1 Sloping

The study analyzed the cost of digging trenches with sloped sides based on engineering cost data contained in RS Means cost guides27. For the years 1990 and 2001, the study reviewed the relevant guides to identify the combined equipment and labor unit cost (i.e., cost per linear foot) of digging ten different trenches. The trenches differ in slope (five different slopes, including the base case of 0:1 slope [or vertical walls]) and in width (half are 2 feet wide and half are 4 feet wide). All of the trenches have a depth of 10 feet. The analysis then restated the 1990 costs in 2001 dollars using implicit price deflators for U.S. gross domestic product (GDP).

The results of the comparison, presented in Exhibit 5-1 at the end of this chapter, show that the overall cost of trenching using sloping has decreased for all slopes and trench types. The decrease in cost per linear foot ranges from 2.3 to 5.5 percent, and reflects the net result of decreased equipment costs that are partially offset by increased labor costs.

5.2.2 Trench Boxes

The primary cost of using trench boxes consists of the cost of the trench box itself. Although there is some increase in the time required to trench using a trench box as opposed to not using any protective system, research conducted for this study indicates that the loss in productivity is not significant in most cases and, moreover, is comparable to the loss associated with using other protective systems (e.g., shoring). The study obtained trench box monthly rental costs for two different sizes of trench boxes (8 x 16 feet, and 10 x 20 feet) for 1989 and 2001 from Means cost guides28. The study also considered the total cost of a trenching job using each type of trench box, assuming a production rate of 90 linear feet per day (or 1800 linear feet per month)29. As necessary, the study converted costs to 2001 dollars using implicit price deflators for GDP.

The results of the analysis show that the cost of the smaller trench box has declined by approximately 25 percent over the past decade, while the cost of the larger trench box has increased by almost 20 percent. When considered within the context of the overall trenching job, however, these changes in trench box costs prove to be almost insignificant to the cost of trenching overall. Using either size trench box, the overall cost of trenching has declined over the past decade. The size of the decrease is over 3 percent if the small trench box is used and almost 1 percent if the large trench box is used. These findings are shown in Exhibit 5-2.

5.2.3 Aluminum Shoring

The analysis assumes a typical trenching job that uses aluminum shores involves three H-type shores, as well as one pump and associated accessories for the open length of the trench. Current costs were obtained based on vendor quotes30. Past regulatory studies provided information on the 1987 per shore purchase cost associated with a 9 (or 9.5) feet deep, 3-foot wide trench, as well as the pump and accessories31. Although there is some increase in the time required to trench using aluminum shores as opposed to not using any protective system, research conducted for this study indicates that the loss in productivity is not significant in most cases and, moreover, is comparable to the loss associated with using other protective systems (e.g., trench boxes). As necessary, the study converted costs to 2001 dollars using implicit price deflators for GDP.

This analysis, presented in Exhibit 5-3, estimates that the cost of aluminum shore equipment has declined by approximately 10 percent in real dollars since 1987.

5.2.4 Timber Shoring

Research conducted for this study indicates that timber shoring is the most expensive method and is only used when necessary (e.g., to keep an excavation open for an extended period of time). Disadvantages of timber shoring include cost, difficulty finding larger timbers, and risk of occupational injuries to workers handling the heavy timbers. The cost of using timber shoring as a protective system depends largely on the cost of the timber shores; other costs of digging trenches have decreased since the enactment of the Excavations Standard, as discussed above. The study analyzed the cost of timber shoring based on engineering cost data contained in RS Means cost guides32. The study converted costs to 2001 dollars when necessary using implicit price deflators for GDP.

As shown in Exhibit 4, the real price of lumber has decreased over the last decade, with the exception of the cost of large (8 x 8) timbers. The price also can vary with the type of wood available. Therefore, in many cases it may be less expensive to use timber shoring today than in 1989, but in other cases it may currently be more expensive.
Exhibit 5-1
Comparison of Sloping Costs ($ per linear foot)

Trench Size and Slope 1990 Costs 1990 Costs Adjusted to 2001 Dollars 2001 Costs Percent Change1
Equipment Labor Total Equipment Labor Total Equipment Labor Total
2' wide, 10' deep
Slope 0:1 $3.10/LF $4.10 /LF $7.20/LF $3.95/LF $5.23/LF $9.18/LF $3.20/LF $5.70/LF $8.90/LF -3.09%
Slope ˝:1 $8.60/LF $11.10/LF $19.70/LF $10.97/LF $14.16/LF $25.13/LF $8.75/LF $15.50/LF $24.25/LF -3.49%
Slope 1:1 $14.15/LF $17.70/LF $31.85/LF $18.05/LF $22.58/LF $40.63/LF $14.35/LF $24.50/LF $38.85/LF -4.37%
Slope 1˝:1 $15.65/LF  $18.25/LF $33.90/LF $19.96/LF $23.28/LF $43.24/LF $15.80/LF $25.50/LF $41.30/LF -4.49%
Slope 2:1 $17.80/LF $21.00/LF  $38.80/LF $22.70/LF $26.79/LF $49.49/LF $18.00/LF $29.00/LF $47.00/LF -5.03%
4' wide, 10' deep
Slope 0:1 $6.40/LF $8.05/LF $14.45/LF $8.16/LF $10.27/LF $18.43/LF $6.70/LF $11.30/LF $18.00/LF -2.34%
Slope ˝:1 $11.50/LF  $14.15/LF $25.65/LF $14.67/LF $18.05/LF $32.72/LF $11.90/LF $19.85/LF $31.75/LF -2.96%
Slope 1:1 $15.30/LF $18.20/LF $33.50/LF $19.52/LF $23.21/LF $42.73/LF $15.80/LF $25.50/LF $41.30/LF -3.35%
Slope 1˝:1 $18.45 /LF $21.00/LF $39.45/LF $23.53/LF $26.79/LF $50.32/LF $18.95/LF $29.00/LF $47.95/LF -4.71%
Slope 2:1 $21.00 /LF $23.00/LF $44.00/LF $26.79/LF $29.34/LF $56.12/LF $21.00/LF $32.00/LF $53.00/LF -5.57%
1Percent change calculated based on difference between shaded cells.
Exhibit 5-2
Comparison of Trenching Costs using Trench Boxes ($/month)

Cost Element Units 1989 Costs 1990 Costs 1989-90 Cost
Adjusted to 2001 Dollars		 2001 Costs Percent Change2
Labor to Dig Trench (4' wide, 10' deep, 0:1 slope) $/lf   $8.05   $11.30  
Equipment to Dig Trench (4' wide, 10' deep, 0:1 slope) $/lf   $6.40   $6.70  
Subtotal - Dig Trench $/lf   $14.45 $18.44 $18.00  
Subtotal - Dig Trench1 $/month     $33,196 $32,400