One liners - Transportation Engineering for GATE, PSUs - Part 9

Hello there,
How have you been? Here is another round of one liners for your preparation for the GATE and PSUs examinations.

• For Sandy soils, most common method of stabilization is Soil bitumen stabilization.
• For bituminous or asphalt concrete, proportioning of materials is determined from laboratories.
• Limiting gradient on highways is associated with the requirement of maximum tractive effort for a short distance.
• In group index method of flexible pavement design, daily volume of commercial vehicles decides the thickness of base and surface course.
• In bituminous pavement, alligator cracking is mainly due to fatigue arising from repeated stress application.
• The main function of prime coat is to improve bond between the existing base and surfacing of new construction.
• The design of horizontal transition curve length for highways should take into account three factors namely, allowable values of rate of change of centrifugal acceleration and superelevation and the minimum length formula given by the IRC.
• Penetration test is performed for the gradation of the asphalt cement.
• Marshall test is performed for design of bituminous concrete mix.
• Ring and ball test is performed to determine the softening point.
• Benkelman beam test is performed for overlay design.
• Reflection cracking is observed in bituminous overlay over cement concrete surface.
• General landslide prevention works on the hill roads are retaining walls, catch water drains and breast walls.
• In the Los Angeles Abrasion Test on aggregate, if the speed of the drum is increased to 50 rpm, then the abrasion value will increase.
• Low bitumen content in bituminous pavement causes ravelling in bituminous pavement.
• In desire-line diagram width of desire-line is proportional to the number of trips in both directions.

Check the reference book:

Thanks for visit!

One liners - Transportation Engineering for GATE, PSUs - Part 8

Hello there,
How have you been? Here is another round of one liners for your preparation for the GATE and PSUs examinations.

• The aggregates required for one kilometers length of water bound macadam road per meter width and for 10 mm thickness is 12 cubic meter.
• The camber of shoulders in water bound macadam roads is equal to the cross slope of pavement.
• The binder normally used in flexible pavement construction is bitumen.
• In highway construction rolling starts from sides and proceeds to center.
• For the construction of water bound macadam roads, the correct sequence of operations after spreading coarse aggregates is dry rolling, application of screening, wet rolling and application of filler.
• For the penetration macadam construction, the bitumen is sprayed after the aggregates are spread and compacted.
• When bituminous surfacing is done on already existing black top road or over existing cement concrete road, the type of treatment to be given is tack coat.
• A bituminous primer is a high viscosity cut-back.
• The suitable surfacing material for a bridge deck slab is mastic asphalt.
• The thickness of bituminous carpet varies from 20 to 25 mm.
• Sheet asphalt is a sand-bitumen mix without coarse aggregates.
• In highway construction on super-elevated curves, the rolling shall proceed from lower edge towards the upper edge.
• Expansion joints in cement concrete pavements are provided at an interval of 18 m to 21 m.
• Contraction joints are spaced closer than the expansion joints.
• Longitudinal joints are provided in cement concrete roads to prevent longitudinal cracking.
• Warping joints are provided to relieve stresses induced due to warping.
• A hill road is one which passes through a terrain with a cross slope of 25 to 60%.
• In hill roads if several alternate alignments are surveyed which fulfill the geometric standards, then the preferred alignment is the one which has resisting length as minimum.
• The camber is hill roads in case of bituminous surfacing is adopted as 2.5%.
• The super-elevation to be provided in horizontal curves of radius R in hill roads is V^2/(225R).
• The minimum design speed for hairpin bends in hill roads is taken as 20 kmph.
• The drain which is provided parallel to the roadway to intercept and divert the water from hill slopes is known as catch-water drain.
• The walls which are necessary on the hill side of roadway where earth has to be retained from slipping is known as breast wall.
• In hill roads the side drains are provided only on the hill side of the roads.
• Emulsions are used for stabilizing desert sand.
• Soil lime stabilization is very effective for stabilizing black cotton soils.
• Soil lime stabilization is quite effective in warm regions.

Check the reference book:

Thanks for visit!

One liners - Transportation Engineering for GATE, PSUs - Part 7

Hello there,

How have you been? Here is another round of one liners for your preparation for the GATE and PSUs examinations.

• Bottom-most layer of a pavement is called Sub-grade.

• Flexible pavement distribute the wheel load through a set of layers to the sub-grade.

• The number of repetitions, which the pavement thickness designed for a given wheel load should be able to support during the life of a pavement is 1000000.

• Group Index Method of design of flexible pavement is an empirical method based on physical properties of sub-grade soil.

• Minimum and maximum values of a Group Index can be 0 and 20 respectively.

• If the Group Index value of sub-grade is between 5 to 7, then sub-grade is treated as poor.

• Tyre pressure influences the quality of the surface course.

• Rigidity factor for a tyre pressure greater than 7 kg/cm2 is less than 1.

• In a dual wheel assembly if P is equal to each wheel load, S is centre to centre distance of dual wheels and d is the distance between walls of wheels, then total stress due to the dual wheels at any depth greater than S is equivalent to a single wheel load of magnitude 2P.

• Main drawback of CBR method is that it gives the total thickness which remains same irrespective of the quality of materials used in the component layers.

• Critical load positions in a rigid pavement design is taken as interior, edge and corner loading.

Check the reference book:

 Thanks for visit!

One liners - Transportation Engineering for GATE, PSUs - Part 6

Hello there,

How have you been? Here is another round of one liners for your preparation for the GATE and PSUs examinations.

• A traffic rotary is justified where number of intersecting roads is between 4 to 7.
• When a number of roads are meeting at a point and only one of the roads is important, then the suitable shape of rotary is tangent.
• Maximum number of vehicles can be parked with 90 degree parking.
• When the width of kerb parking space and width of street are limited, generally preferred parking system is parallel parking
• As per IRC recommendations, the average level of illumination on important roads carrying fast traffic is 30 lux.
• The most economical lighting layout which is suitable for narrow roads is single side lighting.
• The direct interchange ramp involves diverging to the right side and merging from right.
• In soils having same plasticity index, if liquid limit is increased, then compressibility and permeability increases but dry strength decreases.
• Aim of the Impact test is to check the toughness of road aggregates.
• Los Angleles testing machine is used to find the abrasion value.
• In Dorry's abrasion test, Hardness = [20 - (loss in weight/3)].
• In CBR test the value of CBR is calculated at 2.5 mm and 5 mm penetrations.
• If impact value is between 20 to 30, aggregate is satisfactory for road surfacing.
• The maximum allowable Los Angeles abrasion value for high quality surface course is 30%.
• Percentage of free carbon in bitumen is less than that in tar.
• The ductility value of bitumen for suitability in road construction should not be less than 50 cm.
• The maximum limit of water absorption for aggregate suitable for road construction is 0.6%.
• Penetration test is performed to find out the grade of the bitumen.
• Bitumen of grade 60/70 means, its penetration value is 6 to 7 mm.
• The recommended grade of tar for grouting purpose is RT-5.
• Softening point of bitumen to be used for road construction at a place should be above the maximum temperature at that place.
• For rapid curing cut-backs gasoline is used as oil.
• As per IRC recommendations CBR method is preferred for design of flexible pavements.

Thanks for visit!

One liners - Transportation Engineering for GATE, PSUs - Part 5

Hello there,
How have you been? Here is another round of one liners for your preparation for the GATE and PSUs examinations.

• The diagram which shows the approximate path of vehicles and pedestrian involved in accidents is known as collision diagram.
• With increase in the speed of the traffic stream, the minimum spacing of vehicles increases.
• Traffic volume is equal to  traffic density * traffic speed.
• Practical capacity is also known as design capacity.
• With increase in speed of the traffic stream, the maximum capacity of the lane first increases and then decreases after reaching a maximum value at optimum speed.
• Equivalent factor of passenger car unit(PCU) for a passenger car as per IRC is 1.0.
• Scientific planning of transportation system and mass transit facilities in cities should be based on origin and destination studies.
• The diagram which shows all important physical conditions of an accident location like roadway limits, bridges, trees and all details of roadway conditions is known as condition diagram.
• When the speed of traffic flow becomes zero, then traffic density attains a maximum value whereas traffic volume becomes zero.
• On a right angled road intersection with two way traffic, the total number of conflict points is 24.
• The background of informatory  sign board is yellow.
• Level crossing is indicated by a warning sign.
• "Dead Slow" is a regulatory sign.
• The most efficient traffic signal system is flexible progressive system.
• The provision of traffic signals at inter-sections reduces right angled collisions but may increase rear end collisions.
• Stop or red time of a signal is the sum of go and clearance for the cross flow.
• Clearance time is generally 3 to 5 seconds.
• The cycle length is normally 40 to 60 seconds for two phase signals.
• Centre line markings are used in roadways meant for two way traffic.
• The particular places where pedestrians are to cross the pavement are properly marked by the pavement marking known as crosswalk lines.
• The entrance and exit curves of a rotary have different radii and different widths of pavement.
• When two equally important roads cross roughly at right angles, the suitable shape of central island is circular.
• Beyond 5000 vehicles per hour the rotary may not function efficiently.

Thanks for visit!

One liners - Transportation Engineering for GATE, PSUs - Part 4

Hello There,
I am here to give you another round of one liners from Surveying, for your preparation for GATE and PSUs.

• For a constant value of co-efficient of lateral friction, the value of required super-elevation increases with, increase in speed and with decrease in radius of curve.
• To calculate minimum value of ruling radius of horizontal curves in plain, the design speed is given by 16 kmph.
• The attainment of super-elevation by rotation of pavement about the inner edge of the pavement avoids the drainage problem in the flat terrain.
• Psychological extra widening of pavement depends upon the speed of the vehicle.
• In case of hill roads the extra widening is generally provided on the inner side of the curve.
• The mechanical widening required for a n lanes road is given by   (nl^2)/2R where, l is the length of wheel base of vehicle in meters.
• As per the recommendation of IRC, spiral curve is used as the transition curve in the horizontal alignment of the highways.
• The lower among the values obtained on the basis of allowable rate of change of centrifugal acceleration and based on rate of change of super-elevation, is taken as the design length.
• The maximum design gradient for vertical profile of a road is ruling gradient.
• The camber of a road should be approximately equal to half the longitudinal gradient.
• A cubic parabola is preferred in a valley curve.
• The value of ruling gradient in plains as per the recommendation of IRC is 1 in 30.
• Highway facilities are designed for thirtieth highest hourly volume.
• Enoscope is used to find the spot speed.
• For highway geometric design purposes the speed used is 98th percentile.
• Traffic capacity should always be greater than the traffic volume.
• Length of a vehicle affects extra width of pavements and minimum turning radius.
• The maximum width of a vehicle as per the recommendation of IRC is 2.44 m.
• Desire lines are plotted in origin and destination studies.
• License plate method is preferred for collecting origin and destination data for a small area like a mass business centre or a large intersection.

Thanks for visiting!

Reference: Civil Engineering Objectives by S P Gupta and S P Gupta.

One Liners/MCQs- Transportation Engineering.- part 3

Hello,

Here are few MCQs which might help you with Transportation Engineering.
For more you can write below in the comment box or join my Facebook Page.

1. The camber preferred in concrete roads is

(a) Parabolic Camber

(b) Straight Camber

(c) Combination of parabolic and straight camber

(d) Cubic

Ans: (b) Straight

2. The shoulders are preferred to be

(a) Paved

(b) Rough

(c) Smooth

Ans: (b)

3. To avoid overturning and lateral skidding, the centrifugal ratio and lateral friction must be 

(a) Equal to b/2h

(b) More than b/2h

(c) Less than b/2h

(d) 0

  where b is the wheel base and h is the height of the center of gravity.

Ans: (c)

4. When the longitudinal distance covered is more than the wheel circumferential distance, this phenomenon is called:

(a) Sliding

(b) Skidding

(c) Overturning

(d) Decelerating

Ans: (b)

5. Nagpur road plan was based on 

(a) Star/Radial Road Pattern

(b) Rectangular road pattern

(c) Star/Radial and rectangular road pattern

(d) Star and Grid Pattern

Ans: (d)

 please help to upgrade the article.

Thanks for visit!