Shieldingf

Shielding with a trench box can protect the workers in a trench from cave in.Trench box are different from shoring. Instead  of shoring up or otherwise supporting the trench face ,They are intended primarily to shield workers from cave in and similar incidents.The excavated area beet ween the out side of the trench box and  the face of the trench should be as small as possible.The space between    trench box and the excavation side are back filled to prevent  lateral movement of the box.Shields may not be subjected to load exceeding those which the system was designed to withstand.

Shoring

Shoring is the provision of support system for trench faces used to prevent movement of soil.,under ground utilities,road ways and foundations.Shoring is used when the location or depth of the cut makes,slopping back to the maximum allowable slope-impractical. Shoring system consist of posts, wale  , straits and sheeting. 


Three basic type of shoring's are :

 Timber. 

Hydrolic. 

Pneumatic.

protective system (methods of excavation)

Different protective systems are used in excavation to prevent any accident like cave in using different systems for excavation can be called as a method of excavation.They are ; shielding ,sloping ,shoring ,benching.the determination of angle of slopes ,benches or the choice and design of other protective systems shall be based on the evaluation of pertinent factors such as : type of soil,depth of excavation, possible variations in water content of the materiel while the excavation is open.Anticipated changes in materiel from the exposure to air,sun or water.Loading imposed by structures,equipment,overlying material or stored material ,vibration  from the equipment ,blasting, traffic-or other sources.

Just look forward; What are you see now, Where is the beginning ,Let start our safety from there.

Emergency rescue

Emergency rescue equipment is required when a hazardous atmosphere exits or can  reasonably be expected to exit. 

Requirements includes   :

Respirators must be of the type suitable for the exposure.Employees must be trained in their use and  a respirator program must be instituted. Attended life lines  must provided when employees enter bell bottom pier holes ,deep confined spaces or  the similar hazards .Employees who enter confined space must be trained.

Mobile system warning

The following steps should be taken to prevent vehicles from accidently falling in to trench. Barricades must be installed where necessary.Hand or mechanical signals must be used as required.Stop signals must be installed if there is danger of vehicles falling in to the trench.Soil should be graded away from the excavation.this will help in vehicles control and channelling of run off water.

Exposure to vehicles

Procedures to protect employees from being injured or killed by vehicle traffic include : 

Providing employees with  & requiring them to wear warning vests or other suitable garments marked with or made of reflective or high visibility materials.


Requiring a designated ,trained flag person  along with signs,signals and barricades when necessary.

Exposure of falling loads

Employees must be protected from loads or objects falling from lifting or digging equipment. Procedures includes:


 Employees are not permitted to work under raised loads.

Employees are required to stand away from equipment that is being loaded or UN loaded. 

Equipment operators or truck drivers may stay in their equipment during loading or unloading.

If the  equipment is properly     equipped with a   cab shield or adequate canopy.

Surface crossing of trenches

Surface crossing should be discouraged.If  needed ,vehicle crossing must be designed by and installed  under the supervision of registered professional engineering .Walk ways or bridges must be provided for foot traffic.The surface shall:

have minimum clear width of 20 inches be fitted with standard rails extended a minimum of 24 inches past the surface edge of the trench.