Roadways
Roadways
It is the process of transporting o carrying goods and passengers from tone place to another
Types of transportation
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Road ways
(a) Road
Road is a especially prepared path on which the transport vehicles pass lawfully.
(b) Roadways
Portion of the roads used for traffic. It includes both carriage way and shoulders.
(c) Carriage way
Portion of the road only meant for the vehicular movement is known as carriage ways.
(d) Shoulder
It is the portion of the road between the edge of the carriageway and the edge of the road formation. Width of the shoulders is 2.5 metres. Shoulder is also known as beam or haunch. Shoulder = Roadways-carriageway/2
(e) Right-of-way
It is the area of land procures for the widening of the roadways.
(f) Highway
Important road connecting major cities is usually referred to as a highway.
(h) Super Elevation
It is defined as the inward transverse inclination gives to the cross section of the carriage way.
(i) Design of super Elevation
e = V^2/225 R
Where e is the super elevation
V is the speed of the vehicle in kilometer/hr.
R is the radius of the curve in metres
(j) Camber
This is the rise given at the centre of the carriage of the road. Also called as cross fall or transverse slope.
Classification of roads
(a) National highway
Roads connecting state capitals, industrial centres, major ports and foreign highways. It Runs through length and breadth of the country.
e.g.: NH 1. Amritsar-Ambala cantt-Delhi Road
NH. $ Bombay-Bangalore-Madras Road
NH. 45. Madras- Trichy-Dindigul Road
(b) State highways
Roads connecting district headquarters and important cities within the state are called state highways.
(c) Major district road
Roads that connect important town with district headquarters within the district concerned.
(d) Other district road
These are minor district roads that connect villages with tons.
(e) Villages road
Roads that connect village or to a nearby railway station
Types of roads
The different types of roads generally prepared are
(a) Earth road
It is the cheapest of all roads. It is adopted only for light traffic.
Construction
It has a natural soil foundation. A camber of 1 or 33 in 25 is recommended for earth roads. Graded soil is spread to a thickness of about 10 cm and compacted. Road surface is water cured for 4 days.
(b) Water bound Macadam roads
It is Suitable for animal drawn vehicles and steel tiered vehicles. Village roads and roads in newly developing countries come under this type. Serve as base bitumen and concrete roads. In this type of roads, stone aggregates that are held together that is held together by dust particles of stone and water is sprinkled during compaction using roller.
Construction
The earth surface is dug up to a depth of 30 cm with a camber of 3 to 4 %. Broken stone aggregates 25 mm to 50 mm or 40 mm to 63 mm are spread to the required level. One course construction include – 125 to 150mm. Two course construction up to 225mm. Two course constructions up to 225 mm. Aggregates layer is compressed using 6 to 10 tonne, 3-wheeled power roller. Stone screenings are spread over to fill the voids and rolling is continued till it becomes firm. Water s sprinkled and rolling is done till voids are completely filled. A filler material is spread and is rolled. It is Cured by keeping moist for 15 days.
(b) Concrete roads
Road constructed of cement concrete with or without reinforcement. Road should be laid over well prepared sub-grade. It is Rigid, smooth non-slippery easy maintenance. Laying cost is high requires skilled workmanship.
Construction
Preparation of sub grade
Compressible soils, granular base of broken stone, kankar is provided. Slope 1:72 to 1:100 is given. It is wetted before laying concrete, so that it does not absorb water from concrete.
Placing of concrete an compaction
Concrete is placed on the sun=b-grade. Mix for one course is 1:1.5:2. Mix for two courses is 1:2.5:4 for bottom course. Mix of 1:1:1.5 for top course. Concerning is done in alternate bays to allow for possible shrinkage. Expansion and connection joints are provided using dowel bars.
Finishing
Compaction concrete is levelled and finished. Entire surface in the bay is belted. Unevenness in the surface is removed using wooden flaot. Excess water is removed using straight edge.
Curing
It is cured by using wet bags or wet sand for 24 hours and by ponding water for 7 days.
Treating of joints
It is cured by using wet gunny bags or wet sand for 24 hours and by ponding water for 7 days. Treating of joints
After curing, joints are opened and filled with plastic fillers like mixtures of asphalt or saw dust or coir or hemp yarn.
(d) Bituminous Road
It is free from cracks. It is resistant to weathering agents like rain, wind etc. it is dust free and non-slippery. Offers smooth riding.
Construction
Single and multiple surface treatments
Preparation of base
Loose materials are removed and then camber is provided. Unevenness is removed and the surface is completed.
Laying of bitumen- Aggregates course
Bituminous materials like asphalt and road tar is laid on the base. Crushed stones are spread evenly and rolled using 8 to 10 tonne roller. Then the rolling is done along the length of the road from the edge towards the centre. Laying of multiple courses.
Application of bituminous materials and aggregates is done more than once
Semi-grouting method
Base is prepared and camber is provided to the required level. The course of sand or gravel is spread evenly on the base. Stone aggregates of size 37.5 mm are spread on slurry. Bituminous materials are applied over the surface at a temperature of (10 degree Celsius to 95 degree Celsius). The surface is sealed by spreading aggregates at the top. The road is sealed by spreading aggregates at the top. The road is opened to traffic after 24 hours.
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