What could be the reason for excessive skidding of the tram during start-upand braking?
Show the correct answer
Correct answer
A. Black rail "fen soil".
Explanation
In the photo we see snow-covered tracks leading to the gate of a depot. Excessive slipping of a tram when moving off and braking may be caused by a black rail, the so-called "mada" - the answer is A.
"Mada" is a dark, slippery layer on the top of the rails, formed from a mixture of crushed leaves, dust, grease and moisture. The rail then looks black and gives the wheels very poor grip. Sanded tram tracks (answer B) actually improve grip, and snow (answer C) also makes grip worse, but it is a black rail that is the typical cause of excessive slipping when moving off and braking. On a black rail you move off gently, brake earlier and use the sander.
Legal basis: Art. 19 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)