D67 FACE THE CHALLENGE

A rectangular sedimentation tank is 30 m long, 12 m wide, and has a water depth of 3 m. If the flow rate is 5400 m³/day, calculate the detention time in hours.

• 3 hours

• 8 hours

• 5 hours

• 2 hours

Answer explanation

Volume = 30 × 12 × 3 = 1080 m³. Flow rate = 5400 m³/day = 225 m³/hr. Detention time = 1080 ÷ 225 = 4.8 hr

The primary purpose of a top lateral bracing in a steel bridge is to:

• Resist wind loads
• Support the deck slab
• Carry dead load
• Transfer live load

Answer explanation

Top lateral bracings in steel bridges provide stability against lateral loads like wind.

The standard length of a rail in India for Broad Gauge is:

• 13 m
• 20 m
• 26 m
• 30 m

Answer explanation

For Broad Gauge, standard rail length is 13 m as per Indian Railways specifications.

The minimum thickness of wearing coat over RCC slab in bridges is:

• 20 mm
• 25 mm
• 30 mm
• 35 mm

Answer explanation

IRC specifies a minimum 30 mm thickness for wearing coat over RCC slab.

Which test is used to determine the workability of fresh concrete when it is very low?

• Slump test
• Flow table test
• Compaction factor test
• Vee-Bee consistometer test

Answer explanation

Vee-Bee consistometer is used for very low workability concrete.

The most efficient cross-drainage work when the canal bed is above the drainage bed is:

• Aqueduct
• Super passage
• Level crossing
• Canal siphon

Answer explanation

An aqueduct carries canal water over a drainage channel when the canal bed is higher.

In tacheometry, the additive constant (K) for a stadia rod with an anallatic lens is:

• 100
• 200
• 0
• 50

Answer explanation

With an anallatic lens, the additive constant becomes zero

The most suitable type of pile for marine structures is:

• Timber pile
• Concrete pile
• Steel pile
• Composite pile

Answer explanation

Steel piles resist marine borers and can withstand impact and heavy loads in marine environments.

The permissible limit of turbidity in drinking water as per BIS is:

• 1 NTU
• 2 NTU
• 5 NTU
• 10 NTU

Answer explanation

BIS standard for drinking water turbidity is a maximum of 5 NTU.

The horizontal distance between the point of curve (PC) and point of tangent (PT) in a simple curve is called:

• Tangent length
• Chord length
• Versine
• Mid-ordinate

Answer explanation

Tangent length is the distance from the tangent point to the curve's beginning or end.