How to Construct Railroad Style lines?

[Bill Thoen]

I see what I did wrong... you need to include an OVERLAYCOLOR parameter 
in the CLASS object to get this to show the 'tie' symbol (the example on 
the wiki at  http://mapserver.gis.umn.edu/cgi-bin/wiki.pl?SymbolExamples 
leaves this out too, and so it doesn't work either).  I tied to fix that 
but I couldn't get edit access to the wiki  (and BTW, the word 
"illusive" on that page should probably be "elusive" if anyone's feeling 
pedantic and is able to make some edits there).

What it does is drop a dashed line over the solid line with the dashed 
line set to be 3 times thicker than the solid line. Since the dash 
pattern is 1 pixel followed by 3 empty ones this has the effect of 
creating a line like a string of square beads (e.g. ---o---o---o---o). 
It looks okay, but it's not the classic cartographic symbol for railroads.

Has anyone come up with something better?

Bill Thoen wrote:
> 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
>