Location of the outer signal on Broad Gauge (BG) For BG lines, what is the standard distance at which the outer signal is placed from the station limit to provide adequate braking and approach warning?

Introduction / Context:
Signal placement determines train braking distance, sighting time, and safe approach to stations. The “outer signal” warns drivers before the home signal and is positioned to satisfy both operational needs and safety margins on Broad Gauge routes.

Given Data / Assumptions:

• Gauge: Broad Gauge (BG).
• Normal approach speeds and typical braking characteristics are assumed.
• Standardized distances are used to ensure uniform operation.

Concept / Approach:
The outer signal must be far enough from the station limit to allow a driver to sight the aspect, react, and control the train safely before reaching the home signal. Historical practice on BG has standardized this distance at about 540 m from the station limit, balancing braking needs and signal spacing constraints.

Step-by-Step Solution:
Identify the function of the outer signal: advance warning prior to home.Consider braking/sighting norms for BG operations.Apply standard distance: about 540 m from station limit on BG.

Verification / Alternative check:
Operating manuals and signal-siting guidelines list typical distances for BG, with the 540 m placement being a commonly cited standard for outer signals under conventional conditions.

Why Other Options Are Wrong:
510–530 m or 550 m: These are not the standard benchmark distances and may not provide the designed uniformity across stations.

Common Pitfalls:

• Confusing outer signal with distant signal placement, which can vary more with speed and gradient.
• Overlooking site-specific adjustments (curves, gradients) that may require refined placement.

Final Answer:
540 m