Because after 2010 it would be nice to have more choices than only the normal transport systems.
A rail car would be a containerwagon as big as a CE2/2 Tram and would carry about 50-100 units of each cargo and would drive on its own, so without a locomotive.
but remember, rail cars need other track designs than all others because each rail car only needs one square, but you can couple them and then they would be long enough for normal track designs.
Because of the positive responce, I made a Rail Cars Beta with the following Rail Car Types:
-CHEMICALS & OIL RAIL CAR
-GRAIN & COAL & IRONORE RAIL CAR
-PAPER & LUMBER & STEEL RAIL CAR
-FOOD & GOODS RAIL CAR
-PASSENGERS RAIL CAR
-LIVESTOCK RAIL CAR
-MAIL RAIL CAR
Additional:
Own bridgetype
Own stationtype
Own signals (1 colorlight 1 semaphone)
Own houses (RRC 1-7) Producing waste
Own industry (Waste Processing Plant - accepts waste and produces chemicals)
Comming Soon:
MORE MORE MORE
Track can be crossed with every other tracks, and the Rail Cars Track can be combined with the normal Railway Track but than you cannot place any signals or stations on this combined part of track.
In Beta 3 some vehicles halted when climbing a hill, now there is a HELP RAIL which you can build on the slopes, so that the RRCs will not stop and drive up the hill with full speed. because of that help rail you can save money when you dont need the Help Rail by not building it

Also updated is that there is a Mail Car
Waste Containers are displayed as red barrels.
if you wanna transport waste you better start in the year 2020 because the houses which produce it, are build about 2015-2020. and also produce very large amounts of passengers.
HAVE FUN

PS: be careful with the RRC houses they expand expotencialy when laying a road near to them