On gloss:

garna in sense "tool"
x1 is a rail/railing/bar [tool] supporting/restraining x2, of material x3.
garna in sense "tool"
x1 is a rail/railing/bar [tool] supporting/restraining x2, of material x3.
rengarna in sense "transportation"
g1 is a railway/track/rail for train t1.

In definition:

trene
x1 is a train [vehicle] of cars/units x2 (mass) for rails/system/railroad x3, propelled by x4.
dicre'e
t1 is an electric train [vehicle] of cars/units t2 (mass) for rails/system/railroad t3, propelled by electric motors/systems t4
lajre'e
x1 is a tram/streetcar/trolley (train that runs on streets) of cars x2 on rails x3 propelled by x4.
renytcana
t1 is a railed vehicle station/depot/yard in transport system t2=t3 for cars/wagons/units tr2 (default heavy rail) propelled by tr4
ripygarna
g1 is a bridge railing at bridge g2=c1, of material g3.
roldepre'e
x1 is local train that stops every station of cars/units x2 (mass) for rails/system/railroad x3, propelled by x4.
selre'e
x1 is a train car/unit of train x2 for rails/system/railroad x3, propelled by x4

In notes:

si'ernunda'a
x1 is a snowball fight in which x2 fights x3 over issue x4, using snow/snowballs x5.
gubmace
x1 is a public transit system serving x2 and offering services x3 (ka).
jaldiga
x1=g1 is a bumper on x2=j1, decreasing the collision impact with x3=j2