For Broad Gauge (B.G.) single-track railway tunnels, what is the typical recommended clear width of the tunnel section?

Introduction / Context:
Tunnel cross-sections for railways must provide safe clearances for dynamic envelope, electrification equipment (if any), maintenance walkways, and aerodynamic effects. For Broad Gauge single track, standard practice converges to a moderate width band that balances construction economy with operational safety.

Given Data / Assumptions:

• Gauge: Broad Gauge (single track).
• Quantity: clear width of tunnel section.
• Assume conventional clearance without extraordinary equipment allowances.

Concept / Approach:
Clear width reflects track centerline allowances, sway, and lateral clearances. Typical guidance for B.G. single track sits in the 4.9–5.5 m range, accommodating dynamic sway and minor maintenance space while keeping excavation volumes reasonable. Larger widths are reserved for special provisions (walkways both sides, heavy electrification fixtures) or future-proofing decisions.

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