Transportation Engineering (Civil)

Roads:

Classification (IRC):

• Express highway: controlled access.
• National highway (NH): by NHAI.
• State highway (SH).
• Major district roads.
• Other district / village roads.

Pavement types:

• Flexible: bituminous, asphalt. Designed by CBR / Marshall methods.
• Rigid: concrete pavement. Long life, higher initial cost.

Layers (flexible):

• Subgrade (compacted soil).
• Sub-base.
• Base course.
• Surface course (BC, AC).

Geometric design:

• Sight distance: Stopping, overtaking.
• Horizontal curves: superelevation e + f = V²/(127R).
• Vertical curves: summit, valley.
• Cross slope: 2-2.5% for drainage.

Traffic engineering:

• Volume, density, speed.
• Capacity.
• Level of service (A-F).

Railways (RRB context!):

Track:

• Rails: 60 kg/m (BG mainline), 52 kg/m (older).
• Sleepers: concrete (PSC) most common now.
• Ballast: 25-50 mm crushed stone.
• Gauge: 1676 mm BG (India standard).

Track components:

• Fish plates (joining rails).
• Sleepers (wood, steel, concrete).
• Ballast (depth 250-300 mm).
• Formation level.

Permanent Way (P.Way):

• Includes rail + sleeper + ballast + formation.
• Maintained by P.Way Inspector.

Geometric design of tracks:

• Cant (superelevation): e = G·V²/(127·R).
• Maximum cant: 165 mm (BG).
• Negative cant on curves.
• Cant deficiency: 100 mm typical.

Stations:

• Way side, junction, terminal.
• Platform length (210 m typical for 22-coach rake).

Track Maintenance:

• Through packing, sectional patrol.
• Mechanical: track tamping machines.

RRB JE focus: railway track components, geometric design, IRC road classes, pavement layers.