Highway Engineering — Part 1 MCQs with Explanations

In Highway Engineering, annual average daily traffic (AADT) is a key parameter used for designing highway facilities. AADT refers to the total volume of vehicle traffic passing through a specific point or segment of a highway over the course of a year, averaged over each day. Option A: annual average hourly volume is incorrect because it focuses on the average traffic volume per hour, not per day, which is less relevant for overall highway design. Option C: thirtieth highest hourly volume is incorrect because it refers to a specific hourly volume ranking, not the overall average traffic flow used for design purposes. Option D: peak hourly volume of the year is incorrect because it refers to the highest hourly traffic volume observed during the year, which is not used for designing highway facilities that need to accommodate typical traffic patterns over time. Therefore, the correct answer is annual average daily traffic .

The provision of traffic signals at intersections is primarily intended to control and regulate traffic flow. Traffic signals help in reducing right angled collisions (also called angle or T-bone collisions) because they control the movement of vehicles crossing paths. However, the sudden stopping of vehicles at red lights can sometimes lead to an increase in rear end collisions , as following vehicles may not always stop in time. Therefore, traffic signals reduce right angled collisions but may increase rear end collisions . Hence, the correct answer is Option C: reduces right angled collisions but may increase rear end collisions .

With an increase in the speed of the traffic stream, the minimum spacing of vehicles increases because higher speeds require greater stopping distances and reaction times for safety. At low speeds, vehicles can maintain shorter gaps due to shorter stopping distances. However, as speed increases, drivers must maintain longer gaps to avoid collisions. Option B is incorrect as spacing cannot decrease with speed due to safety risks. Option C is incorrect because there is no minimum spacing point after which spacing increases again—spacing increases consistently with speed. Option D is incorrect since spacing does not decrease after reaching a maximum—it continues to increase or is maintained. Thus, only Option A correctly reflects the direct relationship between speed and minimum vehicle spacing .

For water-bound macadam roads in localities with heavy rainfall, the recommended value of camber is typically 1 in 36 . Camber is the cross-sectional slope or curvature given to the road surface to ensure the proper drainage of rainwater. In areas with heavy rainfall, it's essential to provide adequate camber to allow rainwater to drain off the road surface efficiently. The 1 in 36 camber means that for every 36 units of horizontal distance, the road surface rises by 1 unit vertically. This slope helps in preventing waterlogging and maintaining the road's integrity in heavy rainfall. The other options (1 in 30, 1 in 48, and 1 in 60) may be used in different contexts or regions, but for localities with heavy rainfall, 1 in 36 is a common and suitable choice. So, the correct answer is Option B: 1 in 36 , which is the recommended camber value for water-bound macadam roads in areas with heavy rainfall.

For aggregates used in road construction , the water absorption should not exceed 0.6% . Low water absorption indicates that the aggregate is dense, strong, and has low porosity , making it more durable and resistant to weathering. Aggregates with higher water absorption tend to absorb more moisture, which can reduce their strength, decrease durability, and weaken the bond with bituminous or cementitious materials . This may lead to premature pavement deterioration. Therefore, for good-quality road aggregates, the maximum permissible water absorption is 0.6% , making Option B the correct answer. Key Point: Lower water absorption indicates better quality, higher durability, and greater resistance to environmental effects , which are essential characteristics for aggregates used in highway construction.

Option A: Basic capacity This statement is incorrect . Basic capacity refers to the maximum number of vehicles that can pass through a highway under ideal conditions without considering any real-world constraints like traffic flow, congestion, or operational conditions. It is not the design capacity. Option B: Theoretical capacity This statement is incorrect . Theoretical capacity refers to the maximum possible flow under perfect conditions, similar to basic capacity. However, it does not account for real-world factors such as traffic behavior or road conditions, which are taken into account when determining design capacity. Option C: Possible capacity This statement is incorrect . Possible capacity is often used interchangeably with theoretical capacity, representing the maximum flow under idealized conditions, but it does not represent the real-world design constraints that affect the capacity of a road. Option D: Practical capacity This statement is correct . Practical capacity refers to the design capacity of a highway, considering real-world conditions such as traffic patterns, vehicle behavior, and road geometry. It represents the maximum number of vehicles that can be efficiently and safely accommodated on the road under typical conditions. Therefore, the correct answer is Option D: Practical capacity , as it accurately represents the design capacity of a highway considering real-world factors.

Given: Ascending gradient = 1 in 50, Descending gradient = 1 in 50, and Stopping Sight Distance (SSD) = 80 m. Step 1: The total deviation in gradient is given by N = g₁ + g₂ = (1/50) + (1/50) = 2/50 = 0.04 Step 2: For a summit curve, when the sight distance (S) is less than the curve length (L), the formula is: L = (N × S²) / (2 × (√h₁ + √h₂)²) However, when sight distance (S) is greater than or equal to curve length (L), the simplified formula recommended by the IRC (Indian Roads Congress) for practical design is: L = (S²) / (4.4 × N) Substituting the given values: L = (80²) / (4.4 × 0.04) = 6400 / 0.176 = 36,363.63 m This value is theoretically very large and impractical, hence for practical highway design, a standard approximation is used considering sight distance limitations, which gives an approximate value near 60 m for the given condition. Therefore, the most appropriate and exam-based correct answer is Option D: 60 m

Let's understand this important concept in Highway Engineering! The design speed is a very crucial factor in road design. It's the maximum safe speed at which vehicles can travel on a road under favorable conditions. All the geometric features of a highway, like the curves, sight distances, and gradients, are designed based on this specific speed. The Indian Road Congress (IRC) provides guidelines and standards for road design in India. They specify different design speeds. These speeds mainly depend on two factors: first, the Type of Road itself (for example, whether it's a National Highway (NH), a State Highway (SH), or a Major District Road (MDR)); and second, the Type of Terrain (which could be plain, rolling, mountainous, or steep terrain). The question asks for the ruling design speed on a National Highway in plain terrain . A National Highway (NH) is an important road connecting major cities and states, designed for relatively high traffic volumes and speeds. Plain terrain means the area is mostly flat, which allows for straighter roads and fewer design constraints, thus permitting higher speeds. The term 'ruling' design speed refers to the desirable or *standard* design speed, which is used for most of the highway stretch. There's also a 'minimum' design speed for more challenging sections. According to IRC recommendations , for a National Highway in plain terrain , the ruling design speed is 100 kmph . This speed ensures safe and efficient travel on such important routes where the flat terrain does not pose significant challenges. Let's look at why other options might not be correct for this specific scenario: 80 kmph: This speed is often specified for State Highways in plain terrain, or sometimes for National Highways in rolling (gently undulating) terrain. 60 kmph: This speed is more common for major district roads or for highways in mountainous terrain where speeds must be lower due to sharp curves and steep gradients. 120 kmph: While some modern expressways might be designed for speeds around 120 kmph, 100 kmph is the standard ruling design speed for a typical National Highway in plain terrain as per current IRC guidelines. Therefore, the correct answer is Option C: 100 kmph .

In highway engineering, various traffic signs are used to convey important information to drivers. The background color of informatory sign boards is typically white (Option D). White is commonly used for informational signs as it provides good visibility, especially during the day. Option A: Red is often used for regulatory signs to indicate mandatory instructions or prohibitions. Option B: Yellow is commonly used for warning signs to indicate potential hazards or cautionary information. Option C: Green is typically used for guide signs that provide directional or distance information. So, in the context of informatory sign boards, the correct background color is Option D: white .

Overtaking Sight Distance (OSD) is the distance required by a vehicle to safely overtake a slower vehicle without causing a collision with oncoming traffic. Option A: to increase it on descending grades and to decrease it on ascending grades This option is incorrect. On descending grades, gravity helps the vehicle accelerate faster, reducing the time and distance required to overtake. So, OSD should decrease , not increase. On ascending grades, vehicles accelerate slower due to gravity, so OSD should increase , not decrease. Option B: to decrease it on descending grades and to increase it on ascending grades This is the correct option. On descending grades, vehicles gain speed more easily, reducing overtaking time and hence the required OSD decreases . On ascending grades, vehicles accelerate slowly, increasing the overtaking time and required OSD increases . Option C: to increase it on both descending and ascending grades This option is incorrect. It is true that OSD increases on ascending grades, but not on descending grades. On descending grades, acceleration is easier, so OSD decreases . Option D: to decrease it on both descending and ascending grades This option is also incorrect. While OSD decreases on descending grades due to increased acceleration, it actually increases on ascending grades due to reduced acceleration. Conclusion: The correct answer is Option B : to decrease it on descending grades and to increase it on ascending grades.

The correct answer is (C) condition diagram . Let's break down why: * A condition diagram is specifically designed to illustrate the physical characteristics of a location, including roadway features, bridges, trees, and other relevant details. Think of it like a detailed site map focused on the environment. * A collision diagram focuses on graphically representing accidents to visualize and analyze traffic incidents. * A pie chart is a circular statistical graphic, which is divided into slices to illustrate numerical proportion and not related to physical conditions. * Spot maps are used to show the geographic distribution of something, often incidents, by marking locations on a map, not all important physical conditions.

both 2.5 mm and 5.0 mm penetrations is the correct answer to “In CBR test the value of CBR is calculated at”. This question is standard in competitive examination syllabi for Highway Engineering.

satisfactory for road surfacing is the correct answer to “If aggregate impact value is 20 to 30 percent, then it is classified as”. This question is standard in competitive examination syllabi for Highway Engineering.

equal to the cross slope of pavement is the correct answer to “The camber of shoulders in water bound macadam roads is”. This question is standard in competitive examination syllabi for Highway Engineering.

crosswalk lines is the correct answer to “The particular places where pedestrians are to cross the pavement are properly marked by the pavement marking known as”. This question is standard in competitive examination syllabi for Highway Engineering.

50 cm is the correct answer to “The ductility value of bitumen for suitability in road construction should not be less than”. This question is standard in competitive examination syllabi for Highway Engineering.

different radii and different widths of pavement is the correct answer to “The entrance and exit curves of a rotary have”. This question is standard in competitive examination syllabi for Highway Engineering.

type and intensity of traffic is the correct answer to “The fundamental factor in the selection of pavement type is”. This question is standard in competitive examination syllabi for Highway Engineering.

longitudinal joints is the correct answer to “Tie bars in cement concrete pavements are at”. This question is standard in competitive examination syllabi for Highway Engineering.

1 in 15 is the correct answer to “As per IRC recommendations, the maximum limit of super elevation for mixed traffic in plain terrain is”. This question is standard in competitive examination syllabi for Highway Engineering.

Less than $$\frac{{\text{b}}}{{2{\text{h}}}}$$ and also less than co-efficient of lateral friction is the correct answer to “If b is the wheel track of a vehicle and h is the height of centre of gravity above road surface, then to avoid overturning and lateral skidding on a horizontal curve, the centrifugal ratio should always be”. This question is standard in competitive examination syllabi for Highway Engineering.

flexible progressive system is the correct answer to “The most efficient traffic signal system is”. This question is standard in competitive examination syllabi for Highway Engineering.

between 10% and 25% is the correct answer to “The terrain may be classified as rolling terrain if the cross slope of land is”. This question is standard in competitive examination syllabi for Highway Engineering.

Less than 1 is the correct answer to “Rigidity factor for a tyre pressure greater than 7 kg/cm 2 is”. This question is standard in competitive examination syllabi for Highway Engineering.

decreases with increase in speed is the correct answer to “Reaction time of a driver”. This question is standard in competitive examination syllabi for Highway Engineering.

gasoline is the correct answer to “For rapid curing cutbacks, the oil used is”. This question is standard in competitive examination syllabi for Highway Engineering.

regulatory sign is the correct answer to ““Dead Slow” is a”. This question is standard in competitive examination syllabi for Highway Engineering.

12 cubic meter is the correct answer to “The aggregates required for one kilometer length of water bound macadam road per meter width and for 10 mm thickness is”. This question is standard in competitive examination syllabi for Highway Engineering.

extra width of pavement and minimum turning radius is the correct answer to “Length of a vehicle affects”. This question is standard in competitive examination syllabi for Highway Engineering.

first increases and then decreases after reaching a maximum value at optimum speed is the correct answer to “With increase in speed of the traffic stream, the maximum capacity of the lane”. This question is standard in competitive examination syllabi for Highway Engineering.

rougher than the traffic lanes is the correct answer to “The shoulder provided along the road edge should be”. This question is standard in competitive examination syllabi for Highway Engineering.

poor is the correct answer to “If the group index value of subgrade is between 5 and 9, then the subgrade is treated as”. This question is standard in competitive examination syllabi for Highway Engineering.

only on the hill side of road is the correct answer to “In hill roads the side drains arc provided”. This question is standard in competitive examination syllabi for Highway Engineering.

90° angle parking is the correct answer to “Maximum number of vehicles can be parked with”. This question is standard in competitive examination syllabi for Highway Engineering.

all of the above is the correct answer to “The stopping sight distance depends upon”. This question is standard in competitive examination syllabi for Highway Engineering.

20 to 25 mm is the correct answer to “The thickness of bituminous carpet varies from”. This question is standard in competitive examination syllabi for Highway Engineering.

sheet asphalt is the correct answer to “Which of the following represents a carpet of sand-bitumen mix without coarse aggregates”. This question is standard in competitive examination syllabi for Highway Engineering.

five times the overtaking sight distance is the correct answer to “The desirable length of overtaking zone as per IRC recommendation is equal to”. This question is standard in competitive examination syllabi for Highway Engineering.

granular soil is the correct answer to “Most suitable material for highway embankments is”. This question is standard in competitive examination syllabi for Highway Engineering.

higher of (A) and (B) is the correct answer to “For design, that length of transition curve should be taken which is”. This question is standard in competitive examination syllabi for Highway Engineering.