D69 CHECK YOUR LEVEL

Which drain section is noted for easy construction and combines vertical sides with a curved bottom?

• 'U' shaped surface drain
• Rectangular surface drain
• Semicircular surface drain
• 'V' shaped surface drain

Answer explanation

U-shaped drains have vertical sides with a curved bottom; easy to construct.

Semicircular surface drains are most suitable for:

• Small streets with low discharge
• National highways
• High embankments
• Hill roads only

Answer explanation

They are effective where discharge is small, e.g., small streets.

In urban roads, longitudinal underground drains are preferred mainly because:

• Land width is limited
• They are cheaper
• Open drains are aesthetic
• Flow is always uniform

Answer explanation

Limited right-of-way encourages underground longitudinal drains.

Over 75% of road cross-drainage structures are:

• Bridges
• Culverts
• Causeways
• Channels

Answer explanation

Culverts constitute the majority of cross-drainage works.

Extra widening We on horizontal curves is given by:

• We = (n l^2)/(2R) + V/(9.5 R)
• We = (n l)/R + V/(9.5 R)
• We = (n l^2)/R + V/9.5
• We = (n l)/2R + V/R

Answer explanation

Mechanical plus psychological widening: We = n l^2/(2R) + V/(9.5R).

Off-tracking O for a vehicle on a curve is:

• O = l^2/(2R)
• O = l/R
• O = 2l/R
• O = l^2/R

Answer explanation

Off-tracking equals l^2/(2R).

The ideal transition curve recommended by IRC is:

• Spiral/Clothoid
• Circular
• Cubic parabola
• Lemniscate only

Answer explanation

IRC recommends spiral (clothoid) as ideal TC.

Design of summit curve is governed primarily by:

• Headlight distance

• Comfort condition (jerk)
• Stopping sight distance

• Drainage

Answer explanation

Summit curves are designed for SSD; valley curves for headlight sight distance.

For valley curves, the recommended ideal curve (IRC) is:

• Square parabola
• Circular
• Cubic parabola
• Clothoid

Answer explanation

Valley curve: ideal square parabola; commonly cubic parabola.

A fillet weld is generally not recommended if the angle between fusion faces is:

• < 60°
• 60°–120°
• Exactly 90°
• > 120°

Answer explanation

Fillet welds are suited for 60°–120°; below 60° is not recommended.