trains  are  so  constructed  that  they 
 have to follow a set path. this  path is 
 called  a  "railway", which is comprised 
 of two metal rails, hence  its nickname. 
 because  the  low  friction between  the 
 wheels  of the train and the rail metal, 
 there are limits for how  acute a  curve 
 can  be, and  even more so  for how much 
 the   ground  under  the  rails  can  be 
 sloped. thus a railway is often  not led 
 on top of  hills, rather through them in 
 tunnels  (if   they   are   large),   or 
            artificial chasms.            
 there will be trees on  the side  of the 
 rails, but  not too close, or  they will 
 be  cut down  by  the railway  janitors. 
 there  will  be  plains,  and bodies  of 
 trains  go  by  day and by night.  along 
       the way, there is information      
 scattered,  often put on top  of  poles, 
 to  be interpreted by the train drivers. 
 different  parts  of  the  railway  have 
          different speed limits.         
 sometimes, trains  have to stop and wait 
 for something to  happen, far away. this 
 is  signaled by  red  or  green  lights. 
 many people  follow the  rails  by foot. 
 often  this  proves  to be  the  shorter 
 path  between  two  points. however this 
 is  frowned  upon,   and  very  impolite 
         toward the train drivers!