APSC Assistant Engineer - Transportation Engineering Questions
1. A highway has a design speed of 80 km/h. If the coefficient of friction is 0.35 and superelevation is 0.06, what is the minimum radius of a horizontal curve (in meters)?
b. 250 m
Description: Using the formula R = V² / (127(e + f)), where V = 80 km/h, e = 0.06, f = 0.35: R = 80² / (127 × (0.06 + 0.35)) ≈ 250 m. This ensures safe vehicle navigation on curves.
Description: Using the formula R = V² / (127(e + f)), where V = 80 km/h, e = 0.06, f = 0.35: R = 80² / (127 × (0.06 + 0.35)) ≈ 250 m. This ensures safe vehicle navigation on curves.
2. Which statement is true about the California Bearing Ratio (CBR)?
b. It indicates the strength of subgrade soil
Description: CBR tests soil’s load-bearing capacity for pavement design. It doesn’t measure thickness, signal timing, or asphalt properties.
Description: CBR tests soil’s load-bearing capacity for pavement design. It doesn’t measure thickness, signal timing, or asphalt properties.
3. A road carries 1200 vehicles per hour with 20% heavy vehicles. If the passenger car unit (PCU) for cars is 1 and for heavy vehicles is 3, what is the traffic flow in PCU/hour?
b. 1560
Description: Cars = 1200 × 0.8 = 960 (PCU = 960 × 1 = 960); Heavy vehicles = 1200 × 0.2 = 240 (PCU = 240 × 3 = 720). Total = 960 + 720 = 1560 PCU/hour, used for capacity analysis.
Description: Cars = 1200 × 0.8 = 960 (PCU = 960 × 1 = 960); Heavy vehicles = 1200 × 0.2 = 240 (PCU = 240 × 3 = 720). Total = 960 + 720 = 1560 PCU/hour, used for capacity analysis.
4. Which statement is correct about superelevation?
b. It counteracts centrifugal force on curves
Description: Superelevation banks curves to balance centrifugal force, enhancing safety. It’s irrelevant to straight roads, load capacity, or speed reduction.
Description: Superelevation banks curves to balance centrifugal force, enhancing safety. It’s irrelevant to straight roads, load capacity, or speed reduction.
5. A pavement has a CBR of 5% and carries 1000 commercial vehicles per day. Using the IRC method, what is the approximate pavement thickness in mm?
b. 450 mm
Description: For CBR = 5% and 1000 vehicles/day, IRC charts suggest ~450 mm thickness. This ensures adequate strength for traffic loads.
Description: For CBR = 5% and 1000 vehicles/day, IRC charts suggest ~450 mm thickness. This ensures adequate strength for traffic loads.
6. Which statement is true about traffic signals?
b. They manage conflicting traffic movements
Description: Signals control intersections to prevent collisions, not increase capacity infinitely or reduce speed permanently. Roundabouts may still need signals in high traffic.
Description: Signals control intersections to prevent collisions, not increase capacity infinitely or reduce speed permanently. Roundabouts may still need signals in high traffic.
7. A vehicle travels 100 m in 6 seconds at a constant speed. What is its speed in km/h?
b. 60 km/h
Description: Speed = distance ÷ time = 100 ÷ 6 = 16.67 m/s. Convert: 16.67 × (3600 ÷ 1000) = 60 km/h, relevant for traffic studies.
Description: Speed = distance ÷ time = 100 ÷ 6 = 16.67 m/s. Convert: 16.67 × (3600 ÷ 1000) = 60 km/h, relevant for traffic studies.
8. Which statement is correct about flexible pavements?
b. They distribute loads through layered systems
Description: Flexible pavements (asphalt) spread loads via layers, unlike rigid concrete. They suit heavy traffic but need maintenance.
Description: Flexible pavements (asphalt) spread loads via layers, unlike rigid concrete. They suit heavy traffic but need maintenance.
9. A highway has a stopping sight distance (SSD) requirement of 120 m for a design speed of 60 km/h. If reaction time is 2.5 s, what is the deceleration rate in m/s²?
b. 3.5
Description: SSD = V × t + V²/(2a); V = 60 km/h = 16.67 m/s, t = 2.5 s, SSD = 120 m. Solving: 120 = 16.67 × 2.5 + 16.67²/(2a) → a ≈ 3.5 m/s², ensuring safe stopping.
Description: SSD = V × t + V²/(2a); V = 60 km/h = 16.67 m/s, t = 2.5 s, SSD = 120 m. Solving: 120 = 16.67 × 2.5 + 16.67²/(2a) → a ≈ 3.5 m/s², ensuring safe stopping.
10. Which statement is true about road signs?
b. They guide and regulate traffic
Description: Road signs provide instructions and warnings, enhancing safety and flow. They don’t affect friction or serve merely decorative purposes.
Description: Road signs provide instructions and warnings, enhancing safety and flow. They don’t affect friction or serve merely decorative purposes.
11. A road with 2% grade has a vertical curve length of 100 m. What is the rate of change of grade in % per meter?
b. 0.04
Description: Rate of change = (final grade - initial grade) ÷ length. Assuming +2% to -2%: (2 - (-2)) ÷ 100 = 0.04 %/m, critical for vertical curve design.
Description: Rate of change = (final grade - initial grade) ÷ length. Assuming +2% to -2%: (2 - (-2)) ÷ 100 = 0.04 %/m, critical for vertical curve design.
12. Which statement is true about sight distance?
b. It ensures visibility for safe driving
Description: Sight distance allows drivers to see obstacles, crucial for safety. It applies to all roads and increases with speed.
Description: Sight distance allows drivers to see obstacles, crucial for safety. It applies to all roads and increases with speed.
13. A traffic signal has a cycle length of 60 seconds, with 30 seconds green for one direction. What is the green time ratio?
b. 0.5
Description: Green time ratio = green time ÷ cycle length = 30 ÷ 60 = 0.5. This balances traffic flow at intersections.
Description: Green time ratio = green time ÷ cycle length = 30 ÷ 60 = 0.5. This balances traffic flow at intersections.
14. Which statement is correct about road camber?
b. It facilitates drainage of surface water
Description: Camber slopes the road surface to drain water, preventing damage. It’s not for width, curves only, or strength reduction.
Description: Camber slopes the road surface to drain water, preventing damage. It’s not for width, curves only, or strength reduction.
15. A highway carries 5000 vehicles/day with a growth rate of 5% per year. What is the traffic volume after 3 years?
b. 5951
Description: Using compound growth: Volume = 5000 × (1 + 0.05)³ ≈ 5951 vehicles/day. This predicts future road capacity needs.
Description: Using compound growth: Volume = 5000 × (1 + 0.05)³ ≈ 5951 vehicles/day. This predicts future road capacity needs.
16. Which statement is true about road shoulders?
b. They provide emergency stopping space
Description: Shoulders allow safe stopping and support safety, not regular traffic, thickness, or decoration.
Description: Shoulders allow safe stopping and support safety, not regular traffic, thickness, or decoration.
17. A pavement layer requires 3000 m³ of material for a 5 km road with 7 m width. What is the layer thickness in mm?
b. 85 mm
Description: Volume = length × width × thickness. Solving: 3000 = 5000 × 7 × t → t = 3000 ÷ 35000 ≈ 0.0857 m = 85 mm, typical for base layers.
Description: Volume = length × width × thickness. Solving: 3000 = 5000 × 7 × t → t = 3000 ÷ 35000 ≈ 0.0857 m = 85 mm, typical for base layers.
18. Which statement is true about level of service (LOS)?
b. It evaluates traffic flow quality
Description: LOS rates traffic conditions (A to F), reflecting congestion. It’s not about thickness or alignment.
Description: LOS rates traffic conditions (A to F), reflecting congestion. It’s not about thickness or alignment.
19. A road has a design speed of 50 km/h. If the stopping sight distance is 60 m, what is the approximate reaction time in seconds?
b. 2.0 s
Description: SSD = V × t + V²/(2a); V = 50 km/h = 13.89 m/s, a ≈ 3.5 m/s². Solving 60 = 13.89 × t + 13.89²/(2 × 3.5) → t ≈ 2.0 s, standard for drivers.
Description: SSD = V × t + V²/(2a); V = 50 km/h = 13.89 m/s, a ≈ 3.5 m/s². Solving 60 = 13.89 × t + 13.89²/(2 × 3.5) → t ≈ 2.0 s, standard for drivers.
20. Which statement is correct about bituminous pavements?
b. They use asphalt as a binder
Description: Bituminous pavements are flexible, using asphalt to bind aggregates, ideal for highways. They require compaction and aren’t rigid.
Description: Bituminous pavements are flexible, using asphalt to bind aggregates, ideal for highways. They require compaction and aren’t rigid.
21. The primary purpose of a road base is to:
b. Distribute traffic loads
Description: The base layer spreads loads to the subgrade, preventing failure. Drainage, aesthetics, and friction are secondary or handled elsewhere.
Description: The base layer spreads loads to the subgrade, preventing failure. Drainage, aesthetics, and friction are secondary or handled elsewhere.
22. Which factor most affects stopping sight distance?
b. Vehicle speed
Description: SSD increases with speed due to longer reaction and braking distances. Width, color, and volume have minimal impact.
Description: SSD increases with speed due to longer reaction and braking distances. Width, color, and volume have minimal impact.
23. The purpose of a transition curve is to:
b. Provide gradual curvature change
Description: Transition curves ease vehicles into horizontal curves, enhancing comfort. They don’t affect gradient, thickness, or drainage.
Description: Transition curves ease vehicles into horizontal curves, enhancing comfort. They don’t affect gradient, thickness, or drainage.
24. The IRC recommends a maximum gradient for highways of:
b. 1 in 20
Description: IRC suggests 1 in 20 (5%) for highways to balance vehicle performance and safety. Steeper gradients are avoided.
Description: IRC suggests 1 in 20 (5%) for highways to balance vehicle performance and safety. Steeper gradients are avoided.
25. Which material is commonly used for road surfacing?
b. Asphalt
Description: Asphalt provides a durable, smooth surface for highways. Clay, sand, and gravel are used in lower layers or unpaved roads.
Description: Asphalt provides a durable, smooth surface for highways. Clay, sand, and gravel are used in lower layers or unpaved roads.
26. The primary purpose of traffic islands is to:
b. Separate traffic streams
Description: Traffic islands guide and segregate vehicles, improving safety. They don’t affect speed, width, or friction.
Description: Traffic islands guide and segregate vehicles, improving safety. They don’t affect speed, width, or friction.
27. Which test evaluates aggregate strength for pavements?
b. Los Angeles abrasion test
Description: This test measures aggregate wear resistance, crucial for pavements. Others test bitumen, asphalt, or concrete properties.
Description: This test measures aggregate wear resistance, crucial for pavements. Others test bitumen, asphalt, or concrete properties.
28. The design life of a flexible pavement is typically:
b. 10 years
Description: Flexible pavements are designed for ~10 years per IRC, balancing cost and durability. Longer lives apply to rigid pavements.
Description: Flexible pavements are designed for ~10 years per IRC, balancing cost and durability. Longer lives apply to rigid pavements.
29. The primary function of a road subgrade is to:
b. Support pavement layers
Description: The subgrade bears all pavement loads, requiring strength. Surfacing, drainage, and friction are handled by other layers.
Description: The subgrade bears all pavement loads, requiring strength. Surfacing, drainage, and friction are handled by other layers.
30. Which factor is critical for intersection design?
b. Traffic volume
Description: Intersection design depends on traffic volume for safety and efficiency. Color, depth, and length are secondary.
Description: Intersection design depends on traffic volume for safety and efficiency. Color, depth, and length are secondary.
31. The purpose of a road median is to:
b. Separate opposing traffic
Description: Medians prevent head-on collisions by dividing traffic. They don’t affect width, speed, or drainage primarily.
Description: Medians prevent head-on collisions by dividing traffic. They don’t affect width, speed, or drainage primarily.
32. Which pavement layer is directly under the wearing course?
b. Base course
Description: The base course supports the wearing course, distributing loads. Subgrade and sub-base are lower, and soil isn’t a pavement layer.
Description: The base course supports the wearing course, distributing loads. Subgrade and sub-base are lower, and soil isn’t a pavement layer.
33. The primary purpose of road markings is to:
b. Guide and control traffic
Description: Markings direct vehicles and enforce rules, enhancing safety. They don’t affect strength, width, or drainage.
Description: Markings direct vehicles and enforce rules, enhancing safety. They don’t affect strength, width, or drainage.
34. The standard width of a single-lane highway in India is:
b. 3.5 m
Description: IRC specifies 3.5 m for single-lane highways, ensuring safe vehicle passage. Wider lanes are for multi-lane roads.
Description: IRC specifies 3.5 m for single-lane highways, ensuring safe vehicle passage. Wider lanes are for multi-lane roads.
35. Which test determines asphalt binder consistency?
b. Penetration test
Description: Penetration tests measure asphalt hardness for pavement use. Others assess soil or aggregate properties.
Description: Penetration tests measure asphalt hardness for pavement use. Others assess soil or aggregate properties.
36. The primary purpose of a road culvert is to:
b. Facilitate water flow
Description: Culverts channel water under roads, preventing flooding. They don’t affect speed, load, or aesthetics primarily.
Description: Culverts channel water under roads, preventing flooding. They don’t affect speed, load, or aesthetics primarily.
37. Which factor influences pavement design most?
b. Traffic load
Description: Traffic load determines pavement thickness and material for durability. Length, color, and median are secondary.
Description: Traffic load determines pavement thickness and material for durability. Length, color, and median are secondary.
38. The purpose of a road embankment is to:
b. Elevate the road above ground
Description: Embankments raise roads to avoid flooding and ensure stability. They don’t affect alignment, friction, or drainage negatively.
Description: Embankments raise roads to avoid flooding and ensure stability. They don’t affect alignment, friction, or drainage negatively.
39. Which type of curve is used in vertical alignment?
b. Parabolic curve
Description: Parabolic curves smooth vertical transitions for comfort. Circular and spiral curves are for horizontal alignment.
Description: Parabolic curves smooth vertical transitions for comfort. Circular and spiral curves are for horizontal alignment.
40. The primary purpose of a road drainage system is to:
b. Remove water from pavement
Description: Drainage prevents water damage to pavements, ensuring longevity. It doesn’t affect speed, strength, or traffic directly.
Description: Drainage prevents water damage to pavements, ensuring longevity. It doesn’t affect speed, strength, or traffic directly.
41. Which method is used for traffic volume studies?
b. Manual counting
Description: Manual counting records vehicle numbers accurately for planning. Other tests assess material properties, not traffic.
Description: Manual counting records vehicle numbers accurately for planning. Other tests assess material properties, not traffic.
42. The primary purpose of a road alignment is to:
b. Ensure safe and efficient travel
Description: Alignment optimizes road paths for safety and speed. It’s not for thickness, drainage reduction, or aesthetics alone.
Description: Alignment optimizes road paths for safety and speed. It’s not for thickness, drainage reduction, or aesthetics alone.
43. Which factor affects road capacity most?
b. Number of lanes
Description: More lanes increase capacity for vehicles. Color, subgrade, and median have lesser impacts.
Description: More lanes increase capacity for vehicles. Color, subgrade, and median have lesser impacts.
44. The primary purpose of a road gradient is to:
b. Control vertical slope
Description: Gradients manage road steepness for vehicle performance. They don’t affect width, friction, or aesthetics primarily.
Description: Gradients manage road steepness for vehicle performance. They don’t affect width, friction, or aesthetics primarily.
45. Which test assesses pavement skid resistance?
b. Pendulum test
Description: The pendulum test measures surface friction, ensuring safety. Others test soil or material properties.
Description: The pendulum test measures surface friction, ensuring safety. Others test soil or material properties.
46. The primary purpose of a road kerb is to:
b. Define road edges
Description: Kerbs mark boundaries, aiding safety and drainage. They don’t affect capacity, load, or speed.
Description: Kerbs mark boundaries, aiding safety and drainage. They don’t affect capacity, load, or speed.
47. Which factor is critical for road safety?
b. Visibility
Description: Visibility ensures drivers see obstacles, reducing accidents. Color, depth, and median are less critical.
Description: Visibility ensures drivers see obstacles, reducing accidents. Color, depth, and median are less critical.
48. The primary purpose of a road widening on curves is to:
b. Accommodate vehicle paths
Description: Widening allows vehicles to navigate curves safely, accounting for turning radii. It’s not for speed, drainage, or aesthetics.
Description: Widening allows vehicles to navigate curves safely, accounting for turning radii. It’s not for speed, drainage, or aesthetics.
49. Which method is used for pavement thickness design?
b. IRC method
Description: The IRC method uses traffic and soil data for thickness design. Others test concrete, asphalt, or aggregates.
Description: The IRC method uses traffic and soil data for thickness design. Others test concrete, asphalt, or aggregates.
50. The primary purpose of a road survey is to:
b. Collect data for design
Description: Surveys gather terrain and traffic data for road planning. They don’t affect capacity, load, or friction directly.
Description: Surveys gather terrain and traffic data for road planning. They don’t affect capacity, load, or friction directly.