Railway Engineering MCQ with answer and solution

Concept

A cross-country alignment crosses a ridge or watershed. It needs development (loops, zig-zags, spirals) to gain height and a tunnel at the summit.

Step-by-step solution

1. In hilly areas, railway alignments are of two main types: valley lines and cross-country lines. 2. A valley line runs along the valley of a stream. It rises gently and needs little development. 3. A cross-country line must cross the watershed between two valleys. 4. To climb the ridge, the line is lengthened by development (zig-zag, loop, switchback, spiral). 5. Near the top of the ridge, a tunnel is used to cross. 6. So development accompanied by tunneling gives a cross-country alignment.

Explanation

A cross-country alignment goes from one valley to another across a ridge. It must climb steeply, so the length is increased by development methods, and the ridge top is crossed by a tunnel. A valley alignment follows the stream and normally does not need this.

Why the other options are wrong

A: Valley alignment follows the stream with gentle slope and needs little development or tunneling. C: Mountain alignment is a general term, not the specific name for this type. D: Zig-zag is one method of development, not the alignment type itself.

Shortcut

Crossing a ridge = development + tunnel = cross-country line.

Common mistake

Choosing zig-zag because it is a development method. The question asks for the alignment type.