FIELD OF THE INVENTION
This invention relates to a reinforced transition approach road
for a crossover structure and a method of making the same. Crossover
structure includes bridge, cross drainage or flyover.
PRIOR ART
A crossover structure is connected to road by an approach road
which may be flexible type or rigid type comprising road elements built on
the prepared subgrade one above another at the site of construction. The
foundation of the abutment of the crossover structure rests on non-yielding
strata whereas the approach road is prone to settlement due to which a level
difference at the interface between the abutment and approach road gradually
develops and increases with time depending upon the subgrade. When the
level difference at the interface between the abutment and approach road is
substantial, vehicles moving on the interface experience sudden jerks causing
discomfort to passengers. It hinders speed of vehicles and affects smooth
flow of traffic. It may also cause accidents/damage to vehicles particularly
when they are moving at high speed. Besides periodic maintenance to level
up the interface is also required. This is expensive, inconvenient and
troublesome.
DETAILED DESCRIPTION OF THE INVENTION
An object of the invention is to provide a reinforced transition
approach road for a crossover structure which does not give rise to any
significant level difference at the interface between the abutment and the
transition approach road and does not cause sudden jerks to vehicles moving
on the interface and discomfort to passengers.
Another object of the invention is to provide a reinforced
transition approach road for a crossover structure which does not hinder the
speed of vehicles and which allows smooth flow of traffic.
Another object of the invention is to provide a reinforced
transition approach road for a crossover structure which does not cause
accidents/damage to vehicles particularly when they are moving at high speed due
to level difference at the interface between the abutment and the transition approach
road.
Another object of the invention is to provide a reinforced transition
approach road for a crossover structure which does not require periodic •
maintenance to level up the interface between the abutment and the transition road
and avoids expenses and inconvenience and efforts for such purpose.
Another object of the invention is to provide a method of making
such a reinforced transition approach road for a crossover structure which is simple,
easy and convenient to carry out.
According to the invention there is provided a reinforced transition
approach road for a crossover structure such as bridges and the like comprising a
stiffner grid system provided on a subgrade prepared at the site of construction, one
end of the said stiffner grid system being rigidly fixed to an abutment of the said '
crossover structure, said grid being provided with load distributor such as herein
described and road elements being built one above the other on the said stiffner
system.
According to the invention there is also provided a method of making
a reinforced transition approach road for a crossover structure comprising
supporting a stiffner grid system on the prepared subgrade at the site of
construction with one end thereof rigidly fixed to the abutment of the crossover
structure providing a load distributing means thereon and building road elements
on the stiffner system one above another.
The following is a detailed description of the invention with reference
to the accompanying schematic drawings in which the sole Fig 1 is a cut section
isometric view of a reinforced transition approach road and approach road of a
bridge according to an embodiment of the invention.
Referring to Fig 1 of the accompanying drawings, the reinforced
transition approach road 1 comprises a stiffner system comprising a metallic grid 2
supported on the prepared subgrade 3 at the site of construction. The metallic grid
may be made of metal such as aluminium or galvanised iron or steel. One
end of the metallic grid is rigidly fixed to the abutment 4 of the bridge 5.
The interstices 6 of the metallic grid is having granular material 7
compacted therein. 8 is a load distributor comprising a high strength
geosynthetic material sheet provided on the metallic grid. The geosynthetic
material sheet may comprise geotextile or geogrid of 50-60 KN/m. 9 A, 9B,
9C and 9D are road elements built on the stiffner system one above another.
The bridge and transition approach road are connected to road (not shown)
by approach road 10 comprising road elements 10A, 10B, 10C and 10D built
on the prepared subgrade 3 in continuity with the transition approach road in
known manner.
According to the invention the road elements of the transition
approach road are reinforced by the stiffner system whose rate of change of
settlement/deformation gradually reduces from the distal end to the proximal
end depending upon the moment of inertia thereof. Therefore, effective
settlement of the transition approach road at the interface between the
transition approach road and the abutment is minimal and insignificant. This
continues to be so throughout the life time of the transition approach road.
Due to the transition approach road being reinforced by the stiffner system,
settlement/deformation of the transition approach road at the interface
between the transition approach road and the approach road is also gradual
and smooth and is almost in level with the settlement/deformation, if any, of
the approach road. Therefore, there will not be appreciable or significant
level differences between the transition approach road and the abutment and
transition approach road and approach road at the interfaces thereof. As a
result sudden jerks to vehicles moving on the interfaces and discomfort to
passengers is avoided. There is no hindrance to the movement of the
vehicles and there is fast and smooth flow of traffic at the interfaces.
Accidents/damage to vehicles particularly when they are at high speed due to
level differences at the interfaces is eliminated. The invention obviates the
necessity for periodic maintenance to level up the interfaces and avoids
expenses and efforts required for such purpose. The high strength
geosynthetic material sheet ensures proper load distribution over the entire
surface area of the metallic grid.
The rate of settlement/deformation of the stiffiier system
depends on factors such as the load acting on it, modulus of elasticity of the
material of the stiffner system, moment of inertia of the stiffner system, the
stiffness characteristics of the subgrade or subgrade reaction. The
dimensions and material of construction of the stiffner system are decided
and selected having regard to the above factors.
Instead of metallic grid, the stiffner system may comprise
reinforced cement concrete, neoprene or fibreglass. The load distributor
may comprise a metallic sheet such as aluminium or galvanised iron or steel
instead of high strength geosynthetic material sheet. Such variations in
construction are to be construed and understood to be within the scope of the
invention.
We Claim:
1) A reinforced transition approach road for a crossover
structure such as bridges and the like comprising a stiffner grid system (2)
provided on a subgrade (3) prepared at the site of construction, one end of
the said stiffner grid system being rigidly fixed to an abutment (4) of the
said crossover structure, said grid being provided with load distributor (8)
such as herein described and road elements being built one above the other
on the said stiffner system.
2) A reinforced transition approach road for a crossover structure
as claimed in claim 1, wherein the stiffher grid system comprises a metallic,
reinforced cement concrete, neoprene or fibreglass grid having granular
material compacted in the interstices thereof and a load distributor is a high
strength geosynthetic material sheet or metallic sheet provided on the grid.
3) A reinforced transition approach road for a crossover structure
as claimed in claim 2, wherein the metallic grid is made of metal such as
aluminium or galvanised iron or steel.
4) A reinforced transition approach road for a crossover structure
as claimed in claim 2 or 3, wherein the geosynthetic material sheet
comprises geotextile of geogrid having strength characteristic of 50-60
kN/m.
5) A reinforced transition approach road for a crossover structure
as claimed in claim 2, wherein the metallic sheet is made of metal such as
aluminium or galvanised iron or steel.
6) A reinforced transition approach road for a crossover structure
substantially as herein described particularly with reference to figure 1 of
the accompanying drawings.
7) A method of making a reinforced transition approach road for a
crossover structure comprising supporting a stiffher grid system on the
prepared subgrade at the site of construction with one end thereof rigidly
fixed to the abutment of the crossover structure providing a load distributing
means thereon and building road elements on the stiffher system one above
another.
8) A method of making a reinforced transition approach road for a
crossover structure substantially as herein described.
A reinforced transition approach road (1) for a crossover
structure (5) such as bridge, cross drainage or flyover and a method of
making the same. A stiffner system comprising a metallic, reinforced
cement concrete, neoprene or fibreglass grid (2) having granular material (7)
compacted in the interstices (6) thereof and a load distributor (8) comprising
a high strength geosynthetic material sheet or metallic sheet provided on the
grid on the prepared subgrade (3) at the site of construction with one end
thereof rigidly fixed to the abutment (4) of the crossover structure. Road
elements (10A, 10B, 10C, 10D) are built on the stiffner system one above
another (Fig 1).