Refers to the cost of a train ticket or the fare for a train ride. A straightforward compound of 電車 (train) and 賃 (fare/charge).
How much is the train fare to Tokyo?
The train fare has gone up.
Compound of 電車 (densha, 'electric train') and 賃 (chin, 'fare, charge'). The reading ちん for 賃 is the standard on'yomi.