23 - 29 Oct 2025
Specialized Applications - Transit Bridge Geometric Requirements
Estimated Time: 4 min quiz | PDH/CPD: 0.75 hr | Difficulty: Intermediate-Advanced
Question
A rail transit bridge requires track alignment within ±5mm horizontally and ±3mm vertically after all time-dependent effects. The initial closure pour achieves ±2mm accuracy. What additional tolerance must be maintained for long-term effects (creep, shrinkage, temperature)?
Calculation:
Available tolerance = Total tolerance - Initial accuracy
Horizontal: 5mm - 2mm = 3mm remaining
Vertical: 3mm - 2mm = 1mm remaining
Explanation: High-speed rail requires extremely tight tolerances. The remaining tolerance budget must account for concrete creep, thermal movements, and potential settlement. Vertical tolerance is more critical as it directly affects ride quality and dynamic loads.
Learning Resources:
AREMA Manual for Railway Engineering, Chapter 8 - Railway bridge geometric tolerance requirements
UIC High Speed Infrastructure Technical Specifications - Track alignment and construction tolerances
EN 50126/50128 Railway Systems Standards - Safety and reliability requirements for transit infrastructure