Visit www.seminarlinks.blogspot.com to Download. The intersection of railway track and the road at the same level is referred to as a level crossing. In the urban areas the level crossing is generally monitored by qualified railway personnel who monitor the train movement and close the level crossing gate to stop the interfering road traffic but such closing of gates leads to congestion in road traffic and also causes loss of time to road users. Road under bridge and road over the bridge are considered as solutions for avoiding level crossings of roads and railway track.

1. BOX
PUSHING
TECHNIQUE

2. CONVENTIONAL METHOD
Demerits
• Increased time for execution
• Interruption in traffic
• Cost factor was high
Open cut system
• Excavation
• Placing
• Covering
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3. NEED FOR THE ALTERNATIVE
• Present day Intensity of Traffic, both Rail & Road due to the
fast development, is very heavy it cannot the disturbed, for
construction of under bridges or Canal Crossings, drainage
etc by conventional i.e. open cut system.
• Box Pushing Technique is developed where in R.C.C. Boxes
in segments are cast out side and pushed through the heavy
embankments of Rail or Road by Jacking.

4. METHODOLOGY
• Excavation
• Casting of Thrust Bed
• Fabrication of Front and Rear shield
• Box Casting and placing
• Pushing-shifting-pushing operation
• Miscellaneous works
• Precautions

5. Excavation and casting of thrust bed
Open excavation is carried out for construction of Thrust bed

6. Thrust bed
• The Thrustbed and Thrust Beam and keys are designed in R.C.C. to
resist the required Thrust extorted by Jacking force and transfer it to
soil at bottom and sides.
• In cohesive soils even shallow piles are required to transfer the load.
• Provision for Jacking supports is made by providing suitable Pockets
in the bed to accommodate pin supports.
• On completion of Jacking the thrust bed is utilised as floor bed, and so
it is left in place.

7. Box Casting And Pushing
• The RCC Box is cast in segments
of convenient lengths of Total
pushing length.
• The Box section is designed as per
IRS / IRC codes of practice for
loading. Concrete grade normally
kept as M-35.

8. Front Cutting Shield & Rear Jacking Shield
• The First Segment of the precast box is provided with a specially
designed structure named as cutting shield which forms the front
working face with a cutting edge fabricated from 16 to 20 mm thick M.S.
Plates and housed on RCC Box section with suitable anchor bolts.
• Necessary strengthening is provided by stiffeners and face plates of Box
in front on completion of jacking the outer shell of the shield is cut and
removed
• The Rear Jacking shield is provided by anchoring steel plate on the
face of Bottom slab of RCC Box suitably designed to distribute the
jacking load uniformly on concrete area.

9. Fabrication of Front Shield
It is fabricated for cutting action and to provide support , to prevent caving in of soil.

10. Fabrication of Rear Shield
It is provided by anchoring steel plates on the face of bottom slab of
RCC box to suitably distribute the jacking load.

11. Intermediate Jacking Station
• As total length of Box is cast in Segments, each segment is
pushed turn by turn with necessary jacking force and so for this
necessary intermediate jacking stations are provided, with jacking
pockets in bed & walls.

12. Pushing Operation of the Box
• The purpose of pushing of Box is to form a horizontal opening below ground or
through embankments, can say a tunnel, by providing precast box units
underground or an embankment, without disturbing the overhead amenities, like
traffic & structures.
• To reduce the frictional resistance, a thin film of Grease and thick gauge plastic
sheet is provided between the top of the thrustbed & Bottom of the Box.
• This is done before casting of the Bottom slab of the box.
• A Glossy Epoxy layer is also provided to reduce friction on the top and prevent the
disturbance of the mass over box to least during progress of pushing
• Where mass of embankment is less or the soil is of poor quality, drag sheet
system is also considered for least resistance of friction and disturbance of mass
above box.

13. • Auxiliary beds are also provided for casting of the other segments with thin
film of grease and plastic and segments are then brought in alignment of
pushing as and when required as pushing progresses.
• With the progress of jacking, the front unit with shield penetrates into
the embankment and there after excavation within the shield is done
either manually or mechanically and the excavated stuff is transported
outside the working area.
• After the first segment advances to the end of the thrustbed, the second
segment is brought in alignment of the front Box & intermediate jacking
space is lift between the two.
• The progress of pushing is kept continuous and the system of side shifting of
remaining box segments from Auxiliary bed and bring in pushing alignment is
adopted till total length is pushed.

14. Hydraulic Equipment
• The entire Box Pushing system is matter of proper selection of Hydraulic
equipment, as tremendous driving force is required for pushing of medium to
large size of Boxes.
• So for this, Number of Jack units are provided in series for distribution of
pushing load evenly on the face of the concrete, and all Jacks are operated
simultaneously with a common power pack, which supplies uniform flow of
pressure through network of Hydraulic pipes of required pressure capacity,
commencing from front unit to rear unit. Jacking force is applied in sequence.
• This way pushing cycles are repeated till total pushing is completed.

15. Precautions
• Cutting edge of front shield is
fabricated with adequate
thickness of steel plate and the
front edges of the steel plate are
sharpened to facilitate
penetration into the soil.
• To prevent caving of earth
during excavation quantity of
earth shall be removed to barest
minimum duly following the slop
of cutting edge.
• Guide channels to be provided in the
thrust bed to guide the segments to
ensure straight alignment
• The level of the boxes should be
continuously checked.
• The Speed limit should be set to 20 km/h
at the site of construction
• The work should be stopped when a train
is passing over the work.

16. Conclusion
The entire system is purely technical, dependent on Hydraulic system, &
safest method of crossing underground / Embankment, without
disturbing overhead traffic / structures for R.U.B., Canal siphon and
other drainage crossings.
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17. Photo Gallery

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