Highway Engineering MCQ Quiz - Objective Question with Answer for Highway Engineering - Download Free PDF

Explanation:

Concept:

While negotiating curve on road by vehicle, the required centripetal force is provided by the frictional force between the road and tyre.

Centripetal force = \(\frac{mv^2}{R}\) and $\mu mg$

 For avoiding car to skid the centripetal force must be equal to the frictional force ⇒ \(\frac{mv^2}{R} =\mu mg \)   

∴ Maximum speed with which the cyclist can travel without the fear of skidding  \(v=\, \sqrt{\mu Rg}\)

Solution:

Given, Radius of corner = 50 m,  

coefficient of friction between the tires and track =  0.2,

 acceleration due to gravity = 10 m/s2

∴ Maximum speed with which the cyclist can travel without the fear of skidding 

 \(v=\, \sqrt{\mu Rg} = \, \sqrt{0.2\times 50\times 9.81} =\, 9.9 \approx 10\) m/s

Explanation

Centre lines

• A dashed marking is used as a lane divider, or to indicate that a road, or a cycle path, has two-way traffic on it.
• Centre line markings are used in a roadway meant for two-way traffic.

Additional Information 

Turn markings

No passing zone markings

Two-lane roads may have “no passing zones” marked with a SOLID YELLOW LINE. No passing zones are on hills or curves where you cannot see far enough ahead to pass safely. You must complete passing before you enter the no-passing zone.

Stop lines

Stop line indicates the position beyond which the vehicles should not proceed when required to stop by traffic police, traffic signals or other traffic control devices. Stop lines should either be parallel to the intersecting roadway or at right angles to the approaching vehicle.

Explanation:

The extra width of a carriageway that is required on a curved section of a road over and above that is required on a straight alignment is known as Extra Widening.

Mechanical widening: The widening required to account for the off-tracking due to rigidity of wheelbase is known as Mechanical widening. It can be calculated as:

\({W_m} = \frac{{n{l^2}}}{{2R}}\)

n = Number of lanes

l = length of wheelbase = 6.1 m

R = Radius of circular curve

Psychological Widening: Extra width of pavement provided for psychological reasons such as overhangs of vehicles, greater clearance for crossing, etc is known as Psychological Widening.

\({W_{ps}} = \frac{V}{{9.5\sqrt R }}\)

Explanation:

Combination of stresses:

(i) There is no frictional stress at the corner region. Out of various wheel stresses

• Corner stress is minimum as there is a discontinuity in both direction
• Interior stress is maximum
• Edge stress is in intermediate-range

(ii) Temperature stress is critical at the edge and interior and it is minimum at corner. At the corner, resistance due to weight is minimum, hence warping stress is minimum.

(iii) In combination of wheel load and temperature, edge region is mos critical, hence designing is done using edge region stress and however checking is done for corner region.  

Critical cases of stress combination:

(i) Summer mid-day: The critical stress for edge region is given by

Scritical = Sedge + Stemperature - Sfrictional

(ii) Winter, mid-day: The critical combination of stress for the edge region is given by

Scritical = Sedge + Stemperature + Sfrictional

(iii) Mid-nights: The critical combination of stress for the corner region is given by

Scritical = Sedge + Stemperature 

Explanation:

1. Pentaerythritol Tetranitrate (PETN) is a highly explosive compound used in both military and civilian applications, including tunneling operations and in the manufacturing of detonators and explosives.

2. PETN is a powerful, stable explosive and is often used in combination with other materials for controlled demolition or blasting operations.

 Additional InformationTypes of Explosives  

1. Dynamite: A high-energy explosive used in tunneling, effective for breaking hard rock and creating large blasts. It has a relatively quick detonation speed and is versatile for various tunneling conditions.

2. ANFO (Ammonium Nitrate Fuel Oil): A cost-effective, stable explosive often used for bulk blasting in soft to medium rock. It’s favored for large-scale operations due to its efficiency and low cost.

3. PETN (Pentaerythritol Tetranitrate): A highly sensitive explosive with a fast detonation velocity, used in tunneling for precise applications and where controlled blasting is required.

4. Gelignite: Similar to dynamite but with improved stability, Gelignite is commonly used in tunneling where a high degree of control is necessary, particularly in narrow or confined spaces.

5. TNT (Trinitrotoluene): Although less common than dynamite, TNT is used for specialized tunneling projects where a controlled, slower detonation is needed, providing predictable energy release.

Explanation:

As per IS 73 (2013): Paving Bitumen

The requirements for paving bitumen are as follows:

Concept:

The centrifugal force exerted on the vehicles while traversing through the curves is counteracted by providing superelevation, which is given by:​​

\( \;e = \frac{{{V^2}}}{{127R}}\)

However, it is assumed that the centrifugal force is completely nullified if the vehicle is travelling at its 75% of the vehicle design speed.

∴ \( \;e = \frac{{{(0.75V)^2}}}{{127R}} = \frac{{{V^2}}}{{225R}}\)

According to IRC,

Explanation:

Prime coat:

The prime coat is an application of low viscous cutback bitumen to an absorbent surface like granular bases on which binder layer is placed. It provides bonding between two layers. Unlike the tack coat, prime coat penetrates into the layer below, plugs the voids, and forms a watertight surface. 

Seal Coat:

Seal Coat Seal coat is a thin surface treatment used to water-proof the surface and to provide skid resistance.

Tack coat:

Tack coat is a very light application of asphalt, usually asphalt emulsion diluted with water. It provides proper bonding between two layers of binder course and must be thin, uniformly cover the entire surface, and set very fast.

The bituminous prime coat is the first application of low viscosity liquid bituminous material over an existing porous or absorbent pavement surface like the WBM base course. 

Concept:

Theoretical maximum capacity is given by,

\(C = \frac{{1000\;V}}{S}\)

Where,

C = is capacity is vehicle/hr

V = speed in km/hr

S = minimum clear distance between two vehicles

∴ S = 0.2 V + 6 ( if V is in kmph ) 

(or) S = 0.7 v + 6 ( if v is in m/s )

Calculation:

Given,

Velocity (V) = 40 kmph

∵ S = 0.2 V + 6 = 0.2 × 40 + 6 = 14 m

Theoretical Maximum capacity is given by,

\(C = \frac{{1000\;V}}{S}\)

\(C = \frac{{1000\; \times \ 40}}{14}\)

C = 2857.142 Veh/hr ≈ 2860 veh/hr

Concept:

Lag distance = 0.278 × V × t_R

Where,

V = Speed in Kmph

t_R = Reaction time in sec

Calculation:

Lag distance = 0.278 × 47 × 2.5 = 32.665

For two way traffic on a single lane lag distance = 2 × 32.665 = 65.33 m

Explanation:

Transitions curve:

(i) When a vehicle traveling on a straight road enters into a horizontal curve instantaneously, it will cause discomfort to the driver. To avoid this, it is required to provide a transition curve. This may be provided either between a tangent and a circular curve or between two branches of a compound or reverse curve.

Different types of transition curve:

The types of transition curves commonly adopted in horizontal alignment highway are

(i) Spiral or clothoid

(ii) Bernoulli’s Lemniscate

(iii) Cubic parabola

(a) All the three curves follow almost the same path up to deflection angle of 4°, and practically there is no significant difference between even up to 9°. In all these curves, the radius decreases as the length increases.

(b) According to IRC ideal shape for transition curve is spiral because rate of change of radial acceleration remains constant. Generally, spiral curve provided on hilly road.

(c) Cubic parabola is provided for the railway.

 Mandatory Sign (Regulatory sign) → Ex:- Give way, no entry, Stop, No parking

Cautionary sign(warning sign) → Ex:- Narrow road, narrow bridge.

Informatory sign → Ex:- Parking, bus stop

Explanation

The range of paving bitumen is suitable for 7 days Average Maximum Air Temperature is given below(IS 73: 2013, C:5):

Concept:

Peak Hour Factor (PHF):

It compares the traffic volume during the busiest 15 minutes of the peak hour with the total volume during the peak hour. It indicates how consistent traffic volume is during the peak hour.

\(Peak\space Hour\space Factor(PHF)= {Total\space hourly \space volume \over Peak\space 15\space minute\space volume\space within\space the\space hour \times 4}\)

The Highway Capacity Manual advises that in absence of field measurements reasonable approximations for peak hour factor can be made as follows:

• 0.95 for congested condition
• 0.92 for urban areas
• 0.88 for rural areas 

Hence, The ‘Peak hour factor’ is defined as the ratio between the number of vehicles counted during the peak hour and four times the number counted during the highest fifteen consecutive minutes.