HIGHWAY ENGINEERING STUDY MATERIAL FOR SSC JE BY CIVILENGGFORALL FREE DOWNLOAD PDF

GEOMETRIC DESIGN OF HIGHWAYS
SIGHT DISTANCES
HORIZONTAL CURVES
SUPER ELEVATION
EXTRA WIDENING
TRANSITION CURVES
SETBACK DISTANCE
GRADE COMPENSATION
LENGTH OF VERTICAL CURVES
TESTING AND SPECIFICATIONS OF PAVING MATERIALS
BITUMINOUS MATERIALS
TYPES OF BITUMEN
CUTBACK BITUMEN
BITUMINOUS EMULSION
DESIGN OF PAVEMENTS
DESIGN FACTORS
DESIGN OF RIGID PAVEMENT
TRAFFIC CHARACTERISTICS
EFFECTS OF DIMENSION OF VEHICLE
TRAFFIC STUDY
PASSENGER CAR UNITS
CAPACITY FLOW
CONFLICT POINTS AT AN INTERSECTION
ACCIDENT STUDY
PARKING STUDY
ROTARY INTERSECTION
TRAFFIC SIGNS
PROBLEMS AND SOLUTIONS

Highway cross-section elements:

Pavement Surface Characteristics:

(i) Friction (Skid resistance):

It is used to calculate design speed, radius of curves, super elevation, sight distances, etc.
Two phenomena occurring due to friction are skid and slip. Skid occurs when wheel moves without rotating. Slip occurs when wheel rotates more than its corresponding longitudinal distance.
Frictional resistance along the direction of movement of wheel is called longitudinal frictional resistance and perpendicular to it is known as lateral frictional resistance.
IRC recommends coefficient of longitudinal friction as 0.35 to 0.40 and coefficient of lateral friction as 0.15.
Frictional resistance decreases with temperature, wear and tear of tyre, tyre pressure, load, smoothness of pavement and wetness of pavement.

Variation of longitudinal coefficient of friction with speed

(ii) Pavement unevenness:

It is the cumulative measure of vertical unduraturn of pavement surface recorded per unit horizontal distance of road.
It is measured by bump indicator or roughometer and is expressed in terms of unevenness index and unit is usually cm/km.
Lesser the value, better the pavement.
For good pavements, it should be 150 cm/km and 250 cm/km is considered satisfactory.

Camber or Cross-slope:

It is the slope provided along transverse direction for drainage of rain water from road surface and preventing from seepage to layers below surface and water logging.
It is expressed as 1 in n or as percentage.
Depending on shape it can be parabolic, elliptic, straight line or combination of straight line and parabolic.

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Parabolic/Elliptical Camber

most preferred
good for fast-moving traffic

Straight Line Camber

preferred for cement concrete pavement.
used when divider is there at the centre of road or on curved road.

Combination of Straight line and Parabolic Shape

has advantages of both parabolic and straight roads.
useful to increase contact area of wheel.
parabolic at centre and straight at both sides.

Combination of Parabolic and Straight Line Camber

Width of pavement or carriage way:

Width of pavement depends on width of each lane and number of lanes.
Number of lanes depends on predicted traffic volume and capacity of each lane.
Maximum width of vehicles as per IRC is 2.44 m.

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Road margins:

Various elements of margins are:

Shoulders: Provided to serve as an emergency lane. Minimum width recommended is 2.5 m.
Frontage roads
Drive ways
Parking lane
Footpath
Guard rail etc.

Width of road way or formation: Formation width = carriage way width including separations, if any + shoulder.

Right of way:

Area acquired for road, along its alignment. It depends on the number of lanes, importance of road and future development. Right of way = Formation width + Road margins.
NH and SH: Normal width = 45 m Maximum width = 60 m
Distance between: Building line = 80 m Control line = 150 m

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Tests on Bitumen:

Penetration Test: It is used to determine hardness or consistency of bituminous materials. The distance traversed by standard needle in the bituminous materials is measured in 1/10th of a millimeter. Grading of bitumen is done by this value, e.g. 80/100 means penetration value of bitumen is between 80 and 100. At hot climate 30/40 is preferred.
Ductility Test: It is expressed as distance in ‘cm’ to which a standard briquette of bitumen can be stretched before it breaks. Rate of pull: 50 mm/min or 5 cm/min. This test measures elasticity and adhesiveness of bitumen. The ductility value usually varies from 5 cm to 100 cm. Desirable value: 50 cm.
Viscosity Test: It is used to specify the consistency of bitumen. Viscosity is the resistance of flow of the fluid. It is measured by orifice type viscometer. It is determined by measuring number of seconds required for 50 ml of material to flow through standard orifice.
Float Test: It is also used to measure consistency. Float test value is determined by measuring time taken in seconds by water to force its way into the float through the bitumen plug. Higher the value, stiffer the material.
Softening Point Test: It is the temperature at which a substance attains a particular degree of softening under standard test conditions. It is usually measured by Ring and Ball test. For high grade bitumen, softening point will be higher and penetration value will be lesser. Bitumen of higher softening point is preferred in warm climate areas.
Specific Gravity Test: Specific gravity is determined by a pycnometer. Pure bitumen has specific gravity values ranging from 0.97 to 1.02. Cutback bitumen usually has lower specific gravity. Jar has specific value ranging from 1.10 to 1.25.
Flash and Fire Point Test: It is measured by Pensky– Martens apparatus. Flash point is the lowest temperature at which vapour of a substance momentarily catches fire in form of flash. The minimum specified flash point value of bitumen is 175°C. Fire point is the lowest temperature at which the application of test flame causes the material to ignite and burn at least for 5 seconds under specified conditions.
Spot Test: It is used to determine overheated or cracked bitumen. Naptha solution is used for this test.
Loss on Heating Test: Bitumen is heated to 163°C for 5 hours. The specified value for bitumen used for pavement mixes is that it should not be more than 1%.
Solubility Test: Pure bitumen is completely soluble in carbon disulphide (CS₂) and carbon tetrachloride (CCl₄). Solubility is measured as percentage of original sample that dissolves in these solvents. In test with CCl₄, bitumen is considered to be cracked if blank residue is more than 0.5%. In test with CS₂, minimum proportion of bitumen soluble should be 99%.
Water Content Test: Minimum water content in bitumen should be less than 0.2% by weight.