This Safety and Health Information Bulletin is not

a standard or regulation, and it creates no new

legal obligations. The Bulletin is advisory in

nature, informational in content, and is intended to

assist employers in providing a safe and healthful

workplace. Pursuant to the Occupational

Safety and Health Act, employers must comply

with hazard-specific safety and health standards

promulgated by OSHA or by a state with an

OSHA-approved state plan. In addition, pursuant to Section 5(a)(1), the General Duty Clause

of the Act, employers must provide their employees with a workplace free from recognized

hazards likely to cause death or serious physical

harm. Employers can be cited for violating the

General Duty Clause if there is a recognized

hazard and they do not take reasonable steps to

prevent or abate the hazard. However, failure to

implement any recommendations in this Safety

and Health Information Bulletin is not, in itself, a

violation of the General Duty Clause. Citations

can only be based on standards, regulations, and

the General Duty Clause.

U. S. Department of Labor

Occupational Safety and Health Administration

Directorate of Science, Technology & Medicine

Office of Science and Technology Assessment

SHIB 12-30-2004

Safety and Health Information Bulletin

Hazard of Potential Sidewalk Grate System Failure

Preface

Many sidewalks and roadways near large urban

buildings incorporate surface grate systems to cover vaults

and pits. In heavy snowstorms, snow accumulates on the

grates. During a snowstorm in 2003, a skid-steer loader

being used to clear sidewalk snow fell into a vault when

the grate system failed under the weight of the loader, fatally

injuring the operator.

Purpose

The purpose of this Safety and Health

Information Bulletin (SHIB) is to:

• Alert employers and employees who use skidsteer loaders and other heavy machinery to clear

snow or debris from grate systems over pits and

vaults that:

• They must determine whether local

building codes permit heavy machinery to be

operated on sidewalks and over grate systems;

• These grate systems may fail under the

weight of the loaders/machinery;

• Remind employers that OSHA standards for

Walking-Working Surfaces that address floor

opening covers and their supports require that

they meet standard strength and construction

requirements; and

• Recommend that all such surface grate systems

be inspected regularly and remind employers

that steps must be taken to ensure that these

grate systems have the capacity to support the

weight of heavy machinery, unless procedures

are implemented to effectively prevent the

operation of heavy machinery on such grates.

Background

The Occupational Safety and Health

Administration’s (OSHA’s) Braintree,

Massachusetts Area Office investigated a fatal

accident where a skid-steer loader used to clear

snow from sidewalks plunged into a vault when a

metal grate (Figure 1) covering the vault failed.
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Figure 2.

 Figure 3.

 Figure 1.

29 CFR 1910.22(c) requires that “Covers

and/or guardrails shall be provided to protect personnel from the hazards of open pits, tanks, vats, ditches,

etc.”

Accident Description

The accident occurred at a large hospital in

the Boston metropolitan area. Many of the sidewalks

and roadways on the hospital grounds have grates

built flush with the surface to cover vaults or pits. In

heavy snowstorms, snow accumulates on the grates.

The hospital uses two skid-steer loaders to clear snow

from roadways and sidewalks. The grates involved in

this accident were made of aluminum and were bolted

onto steel angle iron that was bolted into the concrete

of the sidewalk vault. At the time of the accident, the

age of the grates and their load capacities were

unknown. The engineering drawings for the grate that

were found after the accident did not reflect the

conditions of the grate system as it was built.

Different crew members drove the skid-steer

loader over the grate on the evening of the accident.

When the victim drove over the grate, the grate

system failed. The bolts attaching the angle iron to the

concrete later were found to be corroded. The load

caused the bolts to fail, pulling the angle iron away

from the concrete and permitting the grates and the

skid-steer loader to drop approximately 20 feet

(Figures 2 & 3). The employee died about an hour

after the accident.

OSHA’s Walking-Working Surfaces

Standards

29 CFR 1910.21(a)(2) defines Floor Opening as “an opening measuring 12 inches or more in its

least dimension, in any floor, platform, pavement, or

yard through which persons may fall; such as a hatchway, stair or ladder opening, pit, or large manhole.”
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Employees who drive equipment with

concentrated loads on wheels (skid-steer loaders,

forklifts or other heavy equipment) on sidewalks or

roadways with flush surface grates are exposed to a

potential hazard. In this accident, the employer

performed regular maintenance checks of the sidewalk

grate and support system. However, the areas subject

to corrosion were not visible during inspections.

The employer installed a new grate system

with sufficient capacity to support heavy equipment

(Figure 4) after the accident.

29 CFR 1910.23(e)(7)(iii) requires that “The

construction of floor opening covers may be of any

material that meets the strength requirements.”

Other Information

Consultation with municipal public works

departments has revealed that some municipalities may

not have specific building code provisions that address

the capability of existing sidewalk grate systems to

support concentrated loads. In addition, there also

may not be specific regulations prohibiting the use of

heavy equipment on sidewalks.

One municipality indicated that, for new

construction of sidewalk grate systems over which

heavy equipment may be operated, it requires that the

grate system’s building plan reflect that the grate

systems are able to support concentrated truck loads

with load capacity certifications provided by a professional structural engineer.

Conclusion

Employers are required to comply with

applicable OSHA standards. In addition, employers

must determine whether local building codes allow

heavy equipment to be operated on sidewalks and, if

so, whether grate systems comply with building code

provisions relating to grate system design and support

capability.

In general, sidewalk grates are designed and

constructed for pedestrian use and are not built with

redundant supports, which are essential when heavy

equipment is operated on sidewalk grate systems.

 Figure 4.

New Grate System

29 CFR 1910.23(a)(5) requires that “Every

pit and trapdoor floor opening, infrequently used, shall

be guarded by a floor opening cover of standard

strength and construction.”

29 CFR 1910.23(e)(7)(i) requires that

“Trench or conduit covers and their supports, when

located in plant roadways, shall be designed to carry a

truck rear-axle load of at least 20,000 pounds.”

The support system for the sidewalk grate at

the Boston-area hospital was not built with redundant

supporting mechanisms and the entire grate system

was not designed for the concentrated load of heavy

equipment such as skid-steer loaders, forklifts or other

vehicles. The steel and concrete interface was subject

to corrosion from weather and salt. The bolts that

anchored the angle iron into the concrete wall were

not visible during regular inspections, so the extent of

the corrosion could not be detected.
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Methods to Address the Hazards

In addition to complying with applicable

OSHA standards and local building codes relevant to

sidewalk grate systems, employers can significantly

reduce the likelihood of a grate system failure by

taking the following steps:

• Develop and communicate written policies

regarding snowplowing or operating

machinery on top of grates.

• Ensure that all operators of heavy machinery

that can access sidewalks or roadways,

know the weight of the machines that they are

operating, the locations of the grates, and the

load capacities of the grates.

• Inventory all sidewalk and roadway grates on

site and perform regular engineering

inspections to determine the condition and

load allowances of all grates.

• Consult with engineers regarding redundant

support structures for new and existing grate

systems.

• Ensure that all engineering drawings for grate

systems are current and reflect the conditions

of the grate systems as they were built.

• When building new vaults, consult with a

professional structural engineer in designing a

concrete shelf system for the angle irons to

rest on and be bolted onto, and certify the

load capacity of the grate system.