Train schedule speed can be increased by

Question

Examoogle · Accepted Answer

Option D: All of these

Explanation & Concepts:
The schedule speed of a train is defined as the ratio of the total distance traveled between two terminal stations to the total time taken, including stops. Increasing the schedule speed requires minimizing the total time taken by improving acceleration/retardation, increasing the top running speed (crest speed), and reducing stationary time at stops.

Working Principle: The relationship is governed by the time equation: $T_{total} = T_{running} + T_{stop}$. By increasing acceleration ($alpha$) and retardation ($eta$), the train reaches crest speed faster and decelerates more efficiently, reducing $T_{running}$. Increasing crest speed ($V_m$) allows the train to cover the distance in a shorter time. Reducing $T_{stop}$ directly subtracts idle time from the denominator of the speed calculation, thereby increasing the overall schedule speed.

Key Formulas: $V_s = \frac{D}{T_{run} + T_{stop}}$ — General expression for schedule speed; $T_{run} = \frac{D}{V_m} + \frac{V_m}{2} (\frac{1}{\alpha} + \frac{1}{\beta})$ — Simplified running time derivation

Key Points: Schedule speed is always lower than average speed, which in turn is lower than crest speed.; Acceleration and retardation rates are limited by passenger comfort and the motor's adhesion limits.; Higher schedule speeds are prioritized in suburban and metro rail systems.; The duration of stops is a critical factor for short-distance journeys (frequent stopping).

Advantages: Improved track utilization; Reduced energy consumption per km when optimized; Enhanced passenger throughput

Disadvantages: Increased wear and tear on braking systems; Higher peak power demand from the traction supply system; Potential passenger discomfort due to high jerk rates

Applications: Metropolitan transit systems; High-speed rail corridors; Suburban commuter lines

Additional Info: Crest speed ($V_m$) is the maximum speed attained by the train during a run.. Option D is correct because all mentioned factors independently and collectively contribute to reducing the travel time for a fixed distance.

Answer: D is correct — Increasing acceleration/retardation, elevating crest speed, and shortening station dwell times are the primary engineering levers to improve train schedule speed.

Exam Tip: Always remember: $V_{schedule}

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Option A: Increasing the acceleration and retardation

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Option B: Increasing the crest speed

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Option C: Decreasing the duration of stop

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