LOW LEVEL & HIGH LEVEL CAUSEWAY

In the name of ALLAH is most beneficent

Most merciful.

04/07/2023

NAME GHULAM

YASINROLL NO

2011-CT-42TOPIC

CAUSEWAY

GOVT COLLEGE OF TECHNOLOGY RASUL MANDI BAHA UL DIN.

Contact # 00923132695514

CAUSEWAYS

• A road causeway is paved dip which allows floods to pass over it. It may or may not have opening or vents for

low water to flow.

TYPES OF CAUSEWAY

1) HIGH LEVEL CAUSEWAY2) LOW LEVEL CAUSEWAY

HIGH LEVEL CAUSEWAYSA high level causeway is submersible road bridge designed to be over toped in floods.* Its formation level is fixed in such a way as not to cause interruption to traffic during flood for more than three days at a time nor for more than six times in a year.

• They are provided with abutments and piers, floors and slabs or arches to form the required no of openings.

• The slopes of approaches is kept as 1 in 20.• when velocity is high and stream bed is soft the

aprons could be of concrete or harder masonry upto a certain distance similarly the road can be formed of cement concrete slab or stone blocks set in cement mortar.

A sufficient no of openings are provided to allow the normal flood discharge to pass through them with the required clearance.

. Temporary causeways which are used for an emergency military operation are formed either by using timber stringer and planking over cribs used as piers or by constructing a culvert using pipes.

• Bed level causeways are provided where period of interruption to traffic at a time does not exceed 24

hours in case of hill roads.

High level causeway

Longitudinal section

Bedding

Toe walls

pier

Deck slab

Road surface

Railings Railings

Cross sectional elevation

For a sound and economical design the factors to be accounted are:

1. Afflux caused by the construction.2. Scour on both u/s and d/s of causeway.3. And the u/s pressure bellow the paved bed.

Factors affecting up gradation of causeways:

1.Numbers of interruption2.Duration of interruption3.Type of flow4.Type and amount of traffic crossing the

causeway5.Importance of road

Requirements of submersible bridge1. These bridges are over toped during heavy floods.2. They are best suitable in hilly terrains.3. They are located on straight reach.4. Cutting is preferred to embankment for approach5. Span length generally should be 1.5 times the

height of pier from the bottom.6. Edge of deck slab are made semi circular to

facilitate smooth flow

• If a causeway has not vent to flow the water then it is called low level causeway.It is also known as Irish bridge.The beds of small rivers or streams, which remains dry for most of the year, or generally passable without a bridge. This involves heavy earth work in cutting for bridge approaches.

LOW LEVEL CAUSEWAY

• Banks of such types of streams are cut down at an easy angle.

• For streams or rivers in plains having sandy beds, it is often sufficient to lay bundles of grass over and across the sandy tracks.

• For crossing the important traffic it is essential to lay a metal or paved or concrete road to prevent against possible scour and undermining a cut off or dwarf wall usually 60 cm deep on up stream side and 120 to 150 cm on down stream side is provided.

For steep banks the road way is carried across the stream at higher level than the bed level.

• In this case masonry construction equal to the width of route and of desired height may be provided.

• The wearing surface is provided over the filling in this case an apron of concrete or masonry should be provided on the down stream side to guard against scouring action as in fig.

X

Y

L-Section

U/S DWARF WALL

D/S DWARF WALL

STONE PAVEMENT

SECTION XY

APRON WALL

D/S DWARF WALLU/S DWARF

WALL

BASE COURSE

HAND RAIL HAND RAIL

PAVED LOW LEVEL CUSEWAY

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