Causes of trench cave-ins:

Several factors contribute to trench cave-ins when considering proper precautions.

Soil stability – related to soil type may be affected by changes in weather.

In the spring, unshored trench walls, & heavy from rain.

Damp soil is exposed to air during excavation, it can dry out and lose the ability to stand on its own, and it will slide into the trench.


Other factors:

• proximity to highways

• large machinery

• backfilled areas

• Existing structures can affect soil stability.

Specific excavation hazards:

1. surface hazards

2. underground utilities

3. getting in and out of the excavation

4. traffic hazards

5. hazardous atmospheres

6. emergency rescue


How can workers be protected?

To prevent cave-ins, excavations can be shored using:

• Timber or other materials

• Sides can be sloped to reduce the “overburden”

• Shield or trench box systems, manufactured or designed by a qualified engineer OSHA requires employers to either slope the sides of excavation walls, use an adequate shoring system (as determined by a qualified engineer), or by equivalent means, such as engineer-designed sheeting or bracing.

Requirements for protective systems-each employee in an excavation must be protected from cave-ins by an adequate protective system designed in accordance with either:

1. Sloping and benching requirements.

2. Support, shield, or other protective systems.

Exceptions would be when:

Excavations are made entirely in stable rock.

Excavations are less than five feet deep and examination of the ground by a competent person provides no indication of a potential cave-in.

The OSHA regulation has four very helpful appendices:

1. Classifying Soil Types

2. Proper Sloping and Benching

3. Timber Shoring

4. Aluminum Hydraulic Shoring

Heavy Equipment Heavy equipment is just what it says it is – ‘HEAVY’. These large and powerful machines can be dangerous to those that work around them as well as those who operate them.

Blind Spots:

The first thing that we need to recognize is that the operator has a limited sight range and blind spots as well. NEVER assume that the operator can see you!

All bi-directional earth moving equipment that has the rear view obstructed must have a backup alarm.

This alarm is an audible device that emits a warning sound to let you know that the piece of equipment is backing up.

ALWAYS observe this warning — look up from what you are doing and make sure you are out of the way. It is often difficult to hear the backup alarm on noisy construction sites, so if you’re working nearby, be cautious and extra alert for the sound of the alarm.

Other types of heavy equipment are equipped with a horn similar to the one that you have in your car. The operator may sound the horn to warn you or to get your attention to let you know that he is about to swing something around or over you.

Pinch Points:

Keep a keen eye out for the movement of equipment, especially around pinch points. These areas should be barricaded off to limit access so no one gets crushed when a crane swings around.


• If you are the operator of heavy equipment, ALWAYS check the brakes, steering, backup alarm, headlights and other controls before starting.

Personal Protective Equipment:

Don’t forget to wear your personal protective equipment. Eye protection, safety boots, hard hat or hearing protection may be required by your employer. If it’s required be sure to wear it.

If the equipment you operate has a seat belt make sure you wear it! No Passengers Allowed:

Another area of concern is those who try to hitch a ride on a piece of equipment. This is absolutely forbidden! To do so will cause an accident should the rider fall off.

A good rule to follow is ‘NO PASSENGERS ALLOWED‘ under ANY circumstances.