CO Road Construction Contractor
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of subgrade preparation in road
construction?
A. To reduce traffic noise
B. To provide a stable foundation for pavement
C. To improve drainage only
D. To increase asphalt thickness
B. To provide a stable foundation for pavement
Rationale: Subgrade preparation ensures the underlying soil can
support the loads from the pavement, preventing future settlement
and cracking.
2. Which material is most commonly used for road base construction?
A. Sand
B. Crushed stone
C. Clay
D. Gravel
B. Crushed stone
Rationale: Crushed stone provides good load-bearing capacity and
stability, which is essential for road base construction.
3. What is the standard maximum slope for a highway embankment?
A. 1:1
B. 1:2
C. 1:3
D. 1:4
C. 1:3
Rationale: A 1:3 slope is commonly used to ensure stability and
prevent sliding of embankments.
,4. Which type of pavement is more suitable for heavy traffic?
A. Gravel pavement
B. Asphalt concrete pavement
C. Bituminous surface treatment
D. Earthen road
B. Asphalt concrete pavement
Rationale: Asphalt concrete pavements provide a durable surface
suitable for heavy traffic loads.
5. What is the primary purpose of a culvert?
A. To strengthen road shoulders
B. To channel water under the road
C. To act as a retaining wall
D. To reduce air pollution
B. To channel water under the road
Rationale: Culverts allow water to flow beneath the roadway,
preventing erosion and flooding.
6. Which compaction method is most effective for granular soils?
A. Static roller
B. Vibratory roller
C. Sheep-foot roller
D. Pneumatic roller
B. Vibratory roller
Rationale: Vibratory rollers are effective for granular soils as the
vibration helps densify loose particles.
7. What is the purpose of prime coating on a road?
A. To waterproof the subgrade
B. To bind loose aggregate
C. To seal cracks in asphalt
D. To improve friction
B. To bind loose aggregate
Rationale: Prime coating provides a tacky layer that binds the
aggregate base before asphalt is applied.
8. In road construction, what does "CBR" stand for?
A. Compacted Base Ratio
B. California Bearing Ratio
C. Compressive Base Resistance
D. Crushed Base Requirement
, B. California Bearing Ratio
Rationale: CBR is a test to evaluate the strength of subgrade and base
materials for road design.
9. Which type of asphalt mix is designed for high-temperature regions?
A. Dense-graded asphalt
B. Open-graded asphalt
C. Stone mastic asphalt
D. Cold mix asphalt
C. Stone mastic asphalt
Rationale: Stone mastic asphalt resists rutting and deformation in
high-temperature regions due to its high stone content.
10. What is the typical thickness of a flexible pavement wearing
course?
A. 50–100 mm
B. 100–150 mm
C. 150–200 mm
D. 200–250 mm
A. 50–100 mm
Rationale: The wearing course is a thin surface layer designed to
resist traffic wear and provide skid resistance.
11. What is the primary factor in determining road alignment?
A. Soil type
B. Traffic volume
C. Topography
D. Construction cost
C. Topography
Rationale: Road alignment is guided by terrain to minimize
earthworks and construction costs while ensuring safety.
12. Which method is used to improve weak subgrades?
A. Soil stabilization
B. Cold mix asphalt
C. Surface dressing
D. Tack coating
A. Soil stabilization
Rationale: Stabilization using lime, cement, or bitumen improves the
strength and load-bearing capacity of weak soils.
Questions And Correct Answers
(Verified Answers) Plus Rationale2026
Q&A| Instant Download Pdf
1. What is the primary purpose of subgrade preparation in road
construction?
A. To reduce traffic noise
B. To provide a stable foundation for pavement
C. To improve drainage only
D. To increase asphalt thickness
B. To provide a stable foundation for pavement
Rationale: Subgrade preparation ensures the underlying soil can
support the loads from the pavement, preventing future settlement
and cracking.
2. Which material is most commonly used for road base construction?
A. Sand
B. Crushed stone
C. Clay
D. Gravel
B. Crushed stone
Rationale: Crushed stone provides good load-bearing capacity and
stability, which is essential for road base construction.
3. What is the standard maximum slope for a highway embankment?
A. 1:1
B. 1:2
C. 1:3
D. 1:4
C. 1:3
Rationale: A 1:3 slope is commonly used to ensure stability and
prevent sliding of embankments.
,4. Which type of pavement is more suitable for heavy traffic?
A. Gravel pavement
B. Asphalt concrete pavement
C. Bituminous surface treatment
D. Earthen road
B. Asphalt concrete pavement
Rationale: Asphalt concrete pavements provide a durable surface
suitable for heavy traffic loads.
5. What is the primary purpose of a culvert?
A. To strengthen road shoulders
B. To channel water under the road
C. To act as a retaining wall
D. To reduce air pollution
B. To channel water under the road
Rationale: Culverts allow water to flow beneath the roadway,
preventing erosion and flooding.
6. Which compaction method is most effective for granular soils?
A. Static roller
B. Vibratory roller
C. Sheep-foot roller
D. Pneumatic roller
B. Vibratory roller
Rationale: Vibratory rollers are effective for granular soils as the
vibration helps densify loose particles.
7. What is the purpose of prime coating on a road?
A. To waterproof the subgrade
B. To bind loose aggregate
C. To seal cracks in asphalt
D. To improve friction
B. To bind loose aggregate
Rationale: Prime coating provides a tacky layer that binds the
aggregate base before asphalt is applied.
8. In road construction, what does "CBR" stand for?
A. Compacted Base Ratio
B. California Bearing Ratio
C. Compressive Base Resistance
D. Crushed Base Requirement
, B. California Bearing Ratio
Rationale: CBR is a test to evaluate the strength of subgrade and base
materials for road design.
9. Which type of asphalt mix is designed for high-temperature regions?
A. Dense-graded asphalt
B. Open-graded asphalt
C. Stone mastic asphalt
D. Cold mix asphalt
C. Stone mastic asphalt
Rationale: Stone mastic asphalt resists rutting and deformation in
high-temperature regions due to its high stone content.
10. What is the typical thickness of a flexible pavement wearing
course?
A. 50–100 mm
B. 100–150 mm
C. 150–200 mm
D. 200–250 mm
A. 50–100 mm
Rationale: The wearing course is a thin surface layer designed to
resist traffic wear and provide skid resistance.
11. What is the primary factor in determining road alignment?
A. Soil type
B. Traffic volume
C. Topography
D. Construction cost
C. Topography
Rationale: Road alignment is guided by terrain to minimize
earthworks and construction costs while ensuring safety.
12. Which method is used to improve weak subgrades?
A. Soil stabilization
B. Cold mix asphalt
C. Surface dressing
D. Tack coating
A. Soil stabilization
Rationale: Stabilization using lime, cement, or bitumen improves the
strength and load-bearing capacity of weak soils.
