An important detail of the metro train is its ability to compensate its performance based on amount of passengers in the train. The Newton’s first law shows that acceleration is equal to force divided by mass (`F = m*a`

or `A = F/m`

), so if the engine power stays the same, increasing number of passengers (and therefore the total mass of the train) would result in train acceleration and deceleration decreasing. The end result is that it takes considerably longer to reach the target speed and the braking distance grows **very** considerably.

To compensate for its weight, the train uses a device called an automode (automatic mode). It’s an electropneumatic device which adjusts both electric and pneumatic performance of the train and its operation is fully recreated in Subtransit. This post only explores the **electric** part of the automode.

Continue reading ‘Compensating Train Performance with Automode – Electric Part’