U. S. Department of Labor

Occupational Safety and Health Administration

Directorate of Science, Technology & Medicine

Office of Science and Technology Assessment

SHIB 08-08-2006

Guardrail System for Tunnel Form Stripping Platform

Safety and Health Information Bulletin

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.

Purpose

To alert general contractors, employers, selfemployed persons, and employees of the risk of falling

from elevations when using “netted” guardrail systems

that are frequently used in conjunction with tunnel form

stripping platforms. Tunnel form stripping platforms

are elevated work platforms covered by the scaffold

standards, Subpart L (construction).

Method (Tunnel Forms)

“Tunnel forms” are steel components, consisting of

a wall section and half of the ceiling width of a

room. The forms can be ganged 40 feet in length.

They are set in place on the opposing wall and the

two sections of the ceiling form are locked

together. The forms are removed by lowering the

jacks, rolling them out through the open end of the

structure on wheels built into the forms, and

picking them up with a crane

With heated tunnel forming systems, walls, floors and

ceilings are cast at the same time. Special heaters

suspended inside the forms speed the curing process,

actually “baking” the concrete. This enhanced curing

process allows the forms to be stripped and

repositioned the next day. Tunnel forms are best

suited to multi-family buildings and attached housing

where room dimensions are repeated, since multiple

units can be created in a single pour.

Background

Occupational fatalities caused by falls remain a serious

public health problem throughout the United States.

Data collected by the Bureau of Labor Statistics

(BLS) Census of Fatal Occupational Injuries

Summary, 2004, reveal 815 fatal work injuries

involving falls.

Recently, an OSHA Area Office inspected a

construction site where the high-rise structure was

being built using “tunnel forms.” Figure No. 1 is an

illustration of the perimeter “netted” guardrail

system which the Compliance Officer observed. It

consists of mesh rope netting attached to top, bottom,

and vertical metal tubing. The guardrail system

attaches to the stripping platform, and extends 39

inches above and 12 to 15 inches below the platform
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edge. There was, however, a horizontal opening of 7

inches measured from the edge of the platform to the

netting. When a tape measure was used to push the

netting away from the platform edge, it created an

opening of at least 19 inches.

As a result of the inspection, citations were issued.

The opening between the platform edge and the

netting could expand to more than 19 inches, and

allow an average-sized worker to fall through the

opening [Figures No.2-1 - 2-4]. Thus, the fall

prevention system did not eliminate all fall hazards.

OSHA Requirements

The OSHA fall protection requirements for employees

working on scaffolds are provided in 29 CFR

1926.451(g). The type of fall protection required by

OSHA depends to some extent on the work activity.

Paragraph 29 CFR 1926.451(g) requires that

employees on a scaffold more than 10 feet above a

lower level be protected from falling to that lower

level. Where fall arrest is not used, 29 CFR

1926.451(g)(4) requires guardrails to be installed on

all open sides and ends of the platform. Guardrail

systems and components are to be designed and built

to meet the requirements of 29 CFR 1926.451(g)(4).

Specfically, when midrails, screens, mesh and

intermediate veritcal members, solid panels, or

equivalent structural members are used, they must

be installed between the top edge of the guardrail

system and the scaffold platform. Upon initial

observation by the Compliance Officer, the

“netted” guardrail system appeared to be securely

fastened to the platform and adjoining side

guardrails. However, upon closer examination it

became apparent that the design of the “netted”

guardrail could easily have allowed an employee to fall

between the netting and the platform to the next lower

level.

The netting and its framing could not support a

downward or horizontal force as specified in

(g)(4)(ix). Although the top edge and side edges

of the “netted” guardrail was securely fastened, the

bottom edge was not properly secured along the

length of the scaffold platform and along the entire

opening between the side supports as required by 29

CFR 1926.451(g)(4)(2).

Employee Training

The employer must assure that each employee who

performs work while on a scaffold is trained by a

person qualified in the subject matter to recognize

the hazards associated with the type of scaffold

being used and to understand the procedures to

control or minimize those hazards. When netted

guardrails are utilized to protect scaffold

perimeters, training must include the need to

properly attach the netting to prevent a fall hazard

between the scaffold floor and the netted guardrail.

The employer must assure that each employee who

is involved in erecting, disassembling, moving,

operating, repairing, maintaining, or inspecting a

scaffold is trained by a competent person to

recognize any hazards associated with the work in

question. In addition to instruction concerning

relevant requirements in Part 1926, Subpart L, the

training must include the following topics, when

applicable:

• The nature of scaffold hazards;

• The correct procedures for erecting,

disassembling, moving, operating,

repairing, inspecting, and maintaining the

type of scaffold in question; and

• The design criteria, maximum intended

load-carrying capacity and intended use of

the scaffold.

Retraining. Retraining must be provided whenever

there is evidence that an employee no longer

possesses the requisite knowledge and skills

needed for safe work involving the erection, use or

dismantling of scaffolds. Retraining is also required

in the following situations:

• where changes at the worksite present a

hazard about which an employee has not

been previously trained;
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• where changes in the types of scaffolds, fall

protection, falling object protection, or

other equipment present a hazard about

which an employee has not been previously

trained; or

• where inadequacies in an affected employee’s

work involving scaffolds indicate that the

employee has not retained the requisite

proficiency.

Should netting or mesh be introduced as part of the

scaffold guardrail system, it would be necessary to

include the need for netting attachment that

prevents a fall hazard.

Conclusion

All scaffold guardrail systems must be installed in

accordance with the provisions in 29 CFR

1926.451(g)(4). In addition, employers must comply

with employee training, inspection, and other OSHA

scaffold provisions that apply to the type(s) of scaffold

used by their employees. Improper use of netting or

mesh used as guardrails for scaffolding can introduce

fall hazards that may require special attention during

installation and inspection. Compliance with these

OSHA provisions will protect employees by

diminishing the likelihood of injuries associated with

falls from scaffolds, including tunnel form stripping

platforms.
Cut-Away View of “Stripping Platform”

(drawing not to scale)

Figure No.1

Figure 1

4

15”

Disclaimer

This is the cut-away view of

scaffold. This side does not

represent an open-ended

platform.

Improperly

guarded

side.
5

Figure 2-1. Description of the potential to fall -

Employee steps into opening

Figure 2-2. Employee looses balance

and begins to fall into netting system

Figure 2-4. Employee clears floor edge and

when the net tightens near the bottom rail it

would have the tendency to push the employee

out of the net

Figure 2-3. Momentum carries

employee downward
6

Underside of Stripping Platform showing mesh guarding.