How to Construct Railroad Style lines?

[Bill Thoen]

It seems that line styles for railroads (i.e. lines that look like  
---|--|--|--|--) are pretty hard to find in the documentation. I did 
find one googlit on the subject from 2003 
(http://mapserver.gis.umn.edu/data2/wilma/mapserver-users/0302/msg00716.html) 
but I can't seem to make it work. The following map file excerpt built 
from that suggestion just seems to produce a simple red line. I don't 
see how this makes the "tie" lie crossways to the track line. Does 
anyone know what I did wrong? Is there a more modern solution?

MAP
  ...
  SYMBOL
      NAME 'line'
      TYPE ELLIPSE
      FILLED TRUE
      POINTS 1 1 END
   END
   SYMBOL
      NAME 'tie'
      TYPE ELLIPSE
      FILLED TRUE
      POINTS 1 1 END
      STYLE 1 3 END
   END
...
  LAYER
      NAME railroads
      GROUP transportation
      TYPE LINE
      STATUS ON
      CONNECTIONTYPE OGR
      CONNECTION "railroads.TAB"
      LABELITEM "Name"
      CLASS
         NAME "Railroads"
         COLOR 255 100 100
         SYMBOL 'line'
         SIZE 1
         OVERLAYSYMBOL 'tie'
         OVERLAYSIZE 3
      END
      PROJECTION
         "init=epsg:4326"
      END
   END
...
END


TIA,
- Bill Thoen