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Which Period is absent in Urban Train Service
Acceleration
Free running
Coasting
Braking
Free running
Urban train services, such as Metro or suburban rail, involve frequent stops and short distances between stations. Consequently, the train does not reach a 'Free Running' period, as the time available is insufficient to reach its balancing speed.
Urban train services, such as Metro or suburban rail, involve frequent stops and short distances between stations. Consequently, the train does not reach a 'Free Running' period, as the time available is insufficient to reach its balancing speed.
TtotalтАЛ=TaccтАЛ+TcoastтАЛ+TbrakeтАЛ тАФ Total time for urban cycle (no free running)
In traction systems, the speed-time curve consists of acceleration, free running, coasting, and braking. For urban services, the acceleration period is followed immediately by the coasting period to maintain energy efficiency, as the train must begin deceleration shortly after reaching peak speed due to the high frequency of stops.
Urban traction is characterized by frequent stops and short station distances.
The absence of free running helps in optimizing energy consumption through extended coasting.
Acceleration in urban transit is typically higher compared to main-line services to achieve required speeds rapidly.
Improved energy efficiency via longer coasting periods
Better adaptation to frequent station stops
Lower average speed compared to main-line trains
High wear and tear on braking systems due to frequent stops
Metro rail networks
Suburban local trains
Main-line services, which have long distances between stations, typically include all four periods: acceleration, free running, coasting, and braking.
Option B (Free running) is absent because the train rarely reaches its steady state speed before the next braking cycle must commence.
B is correct тАФ Urban train services involve short distances between stations, meaning the train does not stay at its balancing speed (Free Running) long enough to constitute a distinct period.
Always remember: Urban = Acceleration + Coasting + Braking; Main-line = Acceleration + Free Running + Coasting + Braking.