100 Highway Engineering Interview Q&A

 Top 100 Highway Engineering Interview Q&A
Top 100 Highway Engineering Interview Q&A


100 Highway Engineering Interview Q&A


Today, I am going to discuss the basic interview questions & answers which are mostly asked in the company of highway construction during the interview, I hope this will help in increasing your basic knowledge in highway engineering.


No.1 – What is IRC?


Ans:- The Full Form of IRC is Indian Road Congress.


No.2 – Maximum Width of Vehicles As per IRC?


Ans:- 2.44mtr.


No.3 – What is the width of the shoulder as per IRC?


Ans:- 2.5mtr.


No.4 – What is the level tolerance in subgrade (for flexible pavement)?


Ans:- +_20mm.


No.5 – What is the Coefficient of Longitudinal friction as per IRC?


Ans:- Longitudinal friction (f) ∞ 1/speed.


No.6 – What is the Coefficient of lateral friction as per IRC?


Ans:- Lateral friction (Lꭍ) = 0.15.


No.7 – Recommended Coefficient of Longitudinal friction as per IRC?


Speed     Longitudinal friction
20-30kmph 0.40
40kmph 0.38
50kmph 0.37
60kmph 0.36
65kmph 0.36
80kmph 0.35
100kmph 0.35


No.8 – Width of Carriageway or main road?


100 Highway Engineering Interview Q&A
100 Highway Engineering Interview Q&A




Single Lane


Two-Lane without raised kerbstone


Intermediate carriageway


Two-lane with a raised kerbstone


Multilane Pavement



No.9 – Total Reaction Time as per IRC?


Ans:- For stopping sight distance – 2.53sec.


For overtaking sight distance – 2sec.


No.10 – Maximum design speed for different roads?


100 Highway Engineering Interview Q&A
100 Highway Engineering Interview Q&A


Roads     Plain Rolling Mountain
1). National Highway or state highway           100km/hr 80km/hr 50km/hr
2). Major district roads 80km/hr 65km/hr 40km/hr
3). Other district roads     65km/hr 50km/hr 30km/hr

4).  Village roads             


40km/hr 25km/hr


No.11 – What is Kerb?


100 Highway Engineering Interview Q&A


Ans:- Kerb is concrete blocks. It is two types:-


i). Semi – barrier type – 15cm(height).


ii). Barrier type – 20cm (height).


No.12 – What are the types of Pavements?


Ans:- There are two types of pavements:-


i). Flexible Pavements.


ii). Rigid Pavements.


No.13 – Difference between Rigid Pavements &  Flexible Pavements?


Flexible Pavements Rigid Pavements
i). Deformation in the subgrade is transferred to the upper layer.                                     Deformation in the subgrade transferred to the subsequence layer.
ii). Have low flexural strength.                       Have high flexural strength.
iii). Have low completion test but high repairing cost.                                                            Have low repairing cost but high completion test.
iv). Damaged by oil & chemicals.                   No Damaged by oil & chemicals.
v). Design based on load distribution factor. Design based on Flexural strength.



No.14 – What is the difference between OGL & NGL?


NGL:- The 1st level taken of the natural ground without using any mechanical means is called NGL.


OGL:- The level taken after preparation of bed by using mechanical means (graders & rollers) is called OGL.


No.15 – Why dowel bars are being provided PQC Pavements?


Dowel bars are required at expansion joints to transfer wheel loads to the adjacent slab.


No.16 – What is the clearance distance between LVUP, VUP & CUP?


a). VUP – 5.5mtr.          B). LVUP – 3.5mtr.       C). CUP – 3mtr. 


No.17 – What is Subbase and Subgrade in Flexible Pavements?


Sub Base:-

The sub-base course is the first layer which is constructed immediately after the subgrade such as GSB & WBM etc.


Sub Grade:-

The base course is a sandwich layer between the wearing course & sub-base course. The base can have multiple layers such as CTB & WMM.


No.18 – Why the mastic is being provided on the deck slab?


Mastic is a protective asphalt layer. It is usually used as the protective layer of the bridge pavement.


No.19 – Define Expressway?


The roads on which only fast-moving vehicles like cars & jeeps are classified and usually higher in comparison to the national highway are known as Expressway.


No.20 –  What is Camber?


The transverse slope was given to the road surface to drain off rainwater from the road surface is called camber.


No.21 – Types of cambers?


i). Parabolic Camber.


ii). Straight Camber.


iii). Combined Parabolic & Straight Camber.


No.22 – Camber recommended in Cement concrete roads?


1 in 50 (2%) to 1 in 60 (1.7%).


No.23 – Camber recommended in Bituminous roads?


1 in 40 (2.5%) to 1 in 50 (2%).


No.24 – Camber recommended in WBM roads?


1 in 33 (3%) or 1 in 40 (2.5%).


No.25 – Define OSD?


The distance is visible to the driver of a vehicle intending to overtake another slow-moving vehicle, without causing any possibility of accidents to the traffic in the opposite direction.


No.26 – Define SSD?


Stopping sight distance is the minimum distance required in which vehicles moving at designed speed can be stopped without colliding with a stationary object on the road surface.


No.27 – Define Slight distance?


It is the actual length of road over which a driver sitting at a specified height in a vehicle can see objects either moving on the road surface.


No.28 – Slight distance depending upon the situation?


i). Stopping sight distance.


ii). Sate overtaking slight distance.


iii). The slight distance at the intersection.


No.29 – Define Dual carriageway?


Each portion of the carriageway is reserved for traffic moving in the

opposite direction. Such carriageways are called dual carriageways.


No.30 – Width of the carriageway in a meter of the two-lane highway?


State highway – 7.0mtr.


No.31 – Define obligatory point?


An obligatory point is such points that act to control points in highway alignment.


No.32 – What are special considerations for hill road alignment?


i). Stability.


ii). Drainage.


iii). Geometric standard.


iv). Resisting length.


No.33 – What are the fundamental principle of alignment?


i). The length of the road should be the shortest.


ii). The proposed road should form a most economical line.


No.34 – What are two types of road projects?


i). A new highway project.


ii). Realignment of the highway project.


No.35 – What are the function that controls the selection of alignment?


i). Volume & types of traffic.


ii). Obligatory points.


iii). Canal river or railway crossings.


iv). Geotechnical standard to be adopted.


No.36 – What is the workability of PQC?


Ans:- 25mm.


No.37 – What are the head involved in highway geometric?


i).  Cross-section elements like – cambers & superelevation.


ii). Slight distance like stopping sight & overtaking slight distance.


iii). Horizontal & vertical alignments.


No.38 – What is the minimum % compaction requirement for embankment & Subgrade?


For embankment 95% & for sub grade 97% relative compaction is required.


No.39 –  Define reaction time?


It is the time in seconds which a driver can take from the instant the objects visible to him to the instant the brakes are effectively applied.


No.40 – Define perception period?


The perception period is the time taken by an average driver to realize a danger ahead before actually trying to apply the breaker.


No.41 –  Define vertical curve?


The curve in the longitudinal section of a highway used to provide an easy change of the gradient.


No.42 – Define horizontal curve?


It is a curve in a plan to provide a change in the direction of the control time by the road surface.


No.43 –  Curve used in the highway?


i). Circular curve.


ii). Transition curve.


iii). Parabolic curve.


No.44 – Effects of centrifugal force?


i). Tendency to overturn the vehicles.


ii). Tendency to skid the vehicles laterally.


No.45 –  Reaction between superelevation, continuant of friction & centrifugal force?


e + f = v ^ 2 / 127R


e – Superelevation whose value is taken as 40 or 1/15.


F – Lateral frictional coefficient.


r  – Radian of the curve in meters, g = 9.8


v –  Speed of vehicles in m/sec.


No.46 –  Define design speed?


The speed is permissible for safe & comfortable driving on a given surface of the highway.


No.47 – Define Right of way (ROW)?


Area acquired along the road alignment is called right of way (ROW).


No.50 – What are hard Shoulders?


The side area of motorway or other roads where we are allowed to stop it if our cars break down. It is generally separated by the white line.


No.51 – Why the saw cut joint is provided in the road curb?


Saw cut helps control Cracking that occurs due to shrinkage in curbs.


No.52 – What is the reasons for bleeding in flexible pavements?


The main reason for bleeding in flexible pavements is the excess of bitumen in the bituminous mix.


No.53 – Minimum Bitumen content in DBM & BC for Grade I?


DBM 4% & 5.2%


No.54 –  X- section of the pavements?

100 Highway Engineering Interview Q&A


No.55 – What is the carriageway?


The width of road used by the traffic for moving on it. It is generally the central position of the total land width.


No.56 – Which type of Emulsion is used in tack coat & prime coat?


In tack coat – RS1 & in the prime coat – SS1.


No.57 – What is the median width in the raised condition in plain, mountainous, and steep terrain?


In-Plane Area generally – 5.0mtr.


In Built-up area – 2.5mtr.


In mountainous & steep terrain – 2.5mtr.


No.58 – Role of separation members in the rigid pavement?


i). It avoids the possibility of active aggressive agents from the soil.


water is attached to the concrete slab.


ii). It reduces friction b/w sub-base & concrete.


iii). It avoids the mixing up of sub-base materials & freshly placed concrete.


iv). It prevents the loss of cement & water in concrete.


No.59 – What is bumping & pumping in concrete?


100 Highway Engineering Interview Q&A


i). A bumping/pumping in subgrade is similar to the concept to try to compact something on a mattress means when a soil compactor rolls over a prepared subgrade soil, It got compacted with the staggered line but when rollers cross over, soil returns to its original position. This type of phenomenon occurs when moisture present in a prepared bed.


No.60 – What is the reason for rutting?


5 main reason for rutting:-


i). Heavy traffic axle.


ii). High temperature & using Vg 30 bitumen.


iii). Higher bitumen content.


iv). More fines bituminous surface.


v). Less air voids in bituminous surface.


No.61 – What is the role of PVC dowel sheets?


It serves to facilitate the movements of dowel bars.


No.62 – What is the role of joint sealant?


It seals the joint width & prevents water & dirt from entering the joints & causing dowel bars corrosion & unexpected joints stress resulting from restrained movements.


No.63 – What is the role of the tie bar?


It prevents lanes from separation & differential deflections & transverse cracking.


No.64 – Minimum right of way should be available for 4 Laning & 6 Laning project as per IRC SP 84 – 2014 & IRC SP87 – 2013?


As per IRC SP 84 -2014 & IRC Sp87 – 2013


A minimum ROW for the development of a  4laning & 6laning – 60mtr.


No.65 –  Minimum design speed for service road?


Minimum design speed for service road shall be adopted 40km/hr.


No.66 – What is Super elevation?


The outer edge of the road is raised above the inner edge is called superelevation or cant or banking.


No.67 – For how many periods flexible pavements design should be done?


A Minimum design period is 15yrs & the operation period is more.


No.68 – For how many periods rigid pavements design should be done?


A Minimum design period is 30yrs & the operation period is more.


No.69 – Minimum width of shoulders as per IRC?


As per IRC, it is 2.5mtr.


No.70 – Minimum spacing between contraction joints?


The minimum spacing is 4.5mtr.


No.71 – Minimum spacing between expansion joints?


The minimum spacing is 140mtr.


No.72 – The roads connecting capital cities of state?


National Highway.


No.73 – Most suitable soil for backfilling in the waterlogged areas?


Cohesive soil.


No.74 – Effects of excessive flexural stress in cc Pavement?


It leads to Pavement cracks.


No.75 – Maximum bitumen content in mastic asphalt?


14 to 17%.


No.76 – MSS stand for?


Mix seal surfacing.


No.77 – IRC was formed in?


In 1928


No.78 – Maximum bitumen content in mastic asphalt?


14 to 17%.


No.79 – MSS stand for?


Mix seal surfacing.


No.80 – IRC was formed in?


In 1928


No.81 – Reaction time in stopping sight distance?




No.82 – SSD stand for?


Long-distance + Breaking distance.


No.83 – Minimum length of overtaking zone?


3 x OSD.


No.84 – Maximum length of overtaking zone?


5 x OSD.


No.85 – Specific gravity of bitumen?


0.97 to 1.02.


No.86 – Specific gravity of Tar?


1.1 to 1.5.


No.87 – Width of Single lane bridge?


4.25mtr as per IRC.


No.88 – Width of double lane bridge?


7.5mtr as per IRC.


No.89 – Intermediate sight distance?


2 x SSD.


No.90 – Value of radian of the simple curve?


Radian ® = 1720meter approx.


No.91 – Define compound curve?


It is a more simple curve that runs in the same direction & joint at a common tangent point.


No.92 – Define reverse curve?


It consists of two simple curves in opposite directions that point at the common tangent point. This point is called the reverse curve.


No.93 – Characteristics of transition curve?


i). It should meet the straight path tangentially.


ii). It should meet the circular curve tangentially.


No.94 – Types of transition curves?


i). True Spiral transitional curve.


ii). Cubical Spiral transitional curve.


iii). Cubic Parabolic transitional curve.


iv). Lemniscates transitional curve.


No.95 – Types of the vertical curves?


i). Summit curve.


ii). Valley curve.


No.96 –  Minimum radian of the vertical curve?


R = L/Q


No.97 – What is a gradient?


It is the rate of rising or fall of road levels along its length.


No.98 – Types of gradient?


i). Maximum gradient.


ii). Puling gradient.


iii). Limiting gradient.


iv). Exceptional gradient.


No.99 – Disadvantages of exceptional gradients?


i). More fuel consumption.


ii). More friction loses.


iii). The efficiency of the engine reduces.


iv). Early fatigue to animals.


No.100 – Types of joints provided in cement concrete pavements?


i). Expansion joints.


ii). Contraction joints.


iii). Warping joints.


iv). Construction Joints.


v). Longitudinal Joints.


I hope this information can be useful for you guys.


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Thanks For the Great Attention!


Good Bye & Take Care


Happy Learning 😆 



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