What is the standard side length of warning (cautionary) traffic sign boards used on roads?

Introduction / Context:
Warning (cautionary) traffic signs are typically equilateral triangles mounted point-up to alert drivers about upcoming hazards. Their dimensions are standardized to ensure legibility and uniformity across networks, with smaller sizes used on lower-category roads and constrained sites.

Given Data / Assumptions:

• Category: warning signs (triangular).
• Question seeks the standard side length used commonly in practice for compact sites and ordinary roads.

Concept / Approach:
While larger triangular signs (for higher-speed roads) are also in use, many standard MCQ references cite a commonly adopted triangular side of about 50 cm for local/low-speed applications, providing sufficient conspicuity without excessive panel size. The dimension relates to minimum legibility at typical approach speeds and balances fabrication/installation constraints.

Step-by-Step Solution:
Identify sign type: equilateral triangle (warning).Select standard compact side length used on regular roads.Adopt 50 cm side length as the answer aligned with common practice references.

Verification / Alternative check:
Field practice often employs larger sizes on highways (for higher speeds), but for many ordinary roads, 50 cm is a widely quoted figure in exam-oriented compilations.

Why Other Options Are Wrong:

• 30–45 cm: too small for consistent legibility.

Common Pitfalls:

• Confusing regulatory (circular) and informatory (rectangular) signs with warning (triangular) sizes.
• Ignoring speed environment when selecting sign size.

Final Answer:
50 cm