The small acute angle between the gauge faces of the stock rail and the tongue (switch) rail in a turnout is termed the

Introduction / Context:
Turnout geometry uses several distinct angles. Confusing them can lead to misinterpretation of design tables or improper field settings. The switch angle specifically relates to the contact geometry between stock and tongue rails that guides wheels into the selected route.

Given Data / Assumptions:

• Standard turnout with a switch and a crossing.
• Gauge faces define the running surfaces for wheel flanges.

Concept / Approach:

The switch angle is measured between the gauge face of the stock rail and the gauge face of the tongue rail when the switch is set for a route. It is typically a very small angle to assure smooth divergence without causing flange climb or impact.

Step-by-Step Solution:

Verification / Alternative check:

Design standards list permitted switch angles and lengths for various turnout numbers and rail sections to guarantee smooth movement and acceptable forces.

Why Other Options Are Wrong:

Angle of crossing refers to the intersection at the frog; angle of turnout relates to the divergence centerline angle; “flaring angle” is not a standard term in this context.

Common Pitfalls:

Assuming switch angle equals turnout angle; neglecting the need for proper planing of tongue rail to achieve the design switch angle.

Final Answer:

Switch angle